From 2fae90c43373f3255226bfa5870a9e7d11b8e2bb Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Sun, 8 Nov 2015 19:29:26 +0100
Subject: [PATCH 01/20] Some code for sending acknowledgements - some of it
 isn't tested - somehow the ack part seems to be empty, even though the flag
 should be set

---
 .../dissem/bitmessage/BitmessageContext.java  |  4 +-
 .../bitmessage/DefaultMessageListener.java    | 23 ++++--
 .../ch/dissem/bitmessage/InternalContext.java | 75 ++++++++++++-------
 .../bitmessage/entity/BitmessageAddress.java  |  8 ++
 .../dissem/bitmessage/entity/Plaintext.java   | 72 +++++++++++++++---
 .../dissem/bitmessage/entity/payload/Ack.java | 33 ++++++++
 .../bitmessage/entity/payload/Pubkey.java     |  4 +
 .../bitmessage/entity/valueobject/Label.java  |  1 +
 .../ch/dissem/bitmessage/factory/Factory.java |  7 ++
 9 files changed, 181 insertions(+), 46 deletions(-)
 create mode 100644 domain/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java

diff --git a/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index 9f4d9a3..8603063 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -156,6 +156,7 @@ public class BitmessageContext {
                 } else {
                     LOG.info("Sending message.");
                     msg.setStatus(DOING_PROOF_OF_WORK);
+                    msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.OUTBOX));
                     ctx.getMessageRepository().save(msg);
                     ctx.send(
                             from,
@@ -165,9 +166,6 @@ public class BitmessageContext {
                             ctx.getNonceTrialsPerByte(to),
                             ctx.getExtraBytes(to)
                     );
-                    msg.setStatus(SENT);
-                    msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.SENT));
-                    ctx.getMessageRepository().save(msg);
                 }
             }
         });
diff --git a/domain/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java b/domain/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
index e069704..c409327 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
@@ -118,15 +118,24 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
         for (BitmessageAddress identity : ctx.getAddressRepo().getIdentities()) {
             try {
                 msg.decrypt(identity.getPrivateKey().getPrivateEncryptionKey());
-                msg.getPlaintext().setTo(identity);
-                if (!object.isSignatureValid(msg.getPlaintext().getFrom().getPubkey())) {
+                Plaintext plaintext = msg.getPlaintext();
+                plaintext.setTo(identity);
+                if (!object.isSignatureValid(plaintext.getFrom().getPubkey())) {
                     LOG.warn("Msg with IV " + object.getInventoryVector() + " was successfully decrypted, but signature check failed. Ignoring.");
                 } else {
-                    msg.getPlaintext().setStatus(RECEIVED);
-                    msg.getPlaintext().addLabels(ctx.getMessageRepository().getLabels(Label.Type.INBOX, Label.Type.UNREAD));
-                    msg.getPlaintext().setInventoryVector(object.getInventoryVector());
-                    ctx.getMessageRepository().save(msg.getPlaintext());
-                    listener.receive(msg.getPlaintext());
+                    plaintext.setStatus(RECEIVED);
+                    plaintext.addLabels(ctx.getMessageRepository().getLabels(Label.Type.INBOX, Label.Type.UNREAD));
+                    plaintext.setInventoryVector(object.getInventoryVector());
+                    ctx.getMessageRepository().save(plaintext);
+                    listener.receive(plaintext);
+
+                    if (identity.has(Pubkey.Feature.DOES_ACK)) {
+                        ObjectMessage ack = plaintext.getAckMessage();
+                        if (ack != null) {
+                            ctx.getInventory().storeObject(ack);
+                            ctx.getNetworkHandler().offer(ack.getInventoryVector());
+                        }
+                    }
                 }
                 break;
             } catch (DecryptionFailedException ignore) {
diff --git a/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java b/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java
index 7a89978..1614548 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java
@@ -17,9 +17,8 @@
 package ch.dissem.bitmessage;
 
 import ch.dissem.bitmessage.entity.*;
-import ch.dissem.bitmessage.entity.payload.Broadcast;
-import ch.dissem.bitmessage.entity.payload.GetPubkey;
-import ch.dissem.bitmessage.entity.payload.ObjectPayload;
+import ch.dissem.bitmessage.entity.payload.*;
+import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.ports.*;
 import ch.dissem.bitmessage.utils.Singleton;
 import ch.dissem.bitmessage.utils.UnixTime;
@@ -29,6 +28,7 @@ import org.slf4j.LoggerFactory;
 import java.io.IOException;
 import java.util.TreeSet;
 
+import static ch.dissem.bitmessage.entity.Plaintext.Status.SENT;
 import static ch.dissem.bitmessage.utils.UnixTime.DAY;
 
 /**
@@ -162,39 +162,35 @@ public class InternalContext {
     public void send(final BitmessageAddress from, BitmessageAddress to, final ObjectPayload payload,
                      final long timeToLive, final long nonceTrialsPerByte, final long extraBytes) {
         try {
-            if (to == null) to = from;
+            final BitmessageAddress recipient = (to != null ? to : from);
             long expires = UnixTime.now(+timeToLive);
             LOG.info("Expires at " + expires);
             final ObjectMessage object = new ObjectMessage.Builder()
-                    .stream(to.getStream())
+                    .stream(recipient.getStream())
                     .expiresTime(expires)
                     .payload(payload)
                     .build();
             if (object.isSigned()) {
                 object.sign(from.getPrivateKey());
             }
-            if (payload instanceof Broadcast) {
-                ((Broadcast) payload).encrypt();
-            } else if (payload instanceof Encrypted) {
-                object.encrypt(to.getPubkey());
+            if (payload instanceof Msg && recipient.has(Pubkey.Feature.DOES_ACK)) {
+                ObjectMessage ackMessage = ((Msg) payload).getPlaintext().getAckMessage();
+                messageCallback.proofOfWorkStarted(payload);
+                security.doProofOfWork(ackMessage, networkNonceTrialsPerByte, networkExtraBytes, new ProofOfWorkEngine.Callback() {
+                    @Override
+                    public void onNonceCalculated(byte[] nonce) {
+                        object.encrypt(recipient.getPubkey());
+                        security.doProofOfWork(object, nonceTrialsPerByte, extraBytes, new ProofOfWorkCallback(object, payload));
+                    }
+                });
+            } else {
+                if (payload instanceof Broadcast) {
+                    ((Broadcast) payload).encrypt();
+                } else if (payload instanceof Encrypted) {
+                    object.encrypt(recipient.getPubkey());
+                }
+                security.doProofOfWork(object, nonceTrialsPerByte, extraBytes, new ProofOfWorkCallback(object, payload));
             }
-            messageCallback.proofOfWorkStarted(payload);
-            security.doProofOfWork(object, nonceTrialsPerByte, extraBytes,
-                    new ProofOfWorkEngine.Callback() {
-                        @Override
-                        public void onNonceCalculated(byte[] nonce) {
-                            object.setNonce(nonce);
-                            messageCallback.proofOfWorkCompleted(payload);
-                            if (payload instanceof PlaintextHolder) {
-                                Plaintext plaintext = ((PlaintextHolder) payload).getPlaintext();
-                                plaintext.setInventoryVector(object.getInventoryVector());
-                                messageRepository.save(plaintext);
-                            }
-                            inventory.storeObject(object);
-                            networkHandler.offer(object.getInventoryVector());
-                            messageCallback.messageOffered(payload, object.getInventoryVector());
-                        }
-                    });
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
@@ -266,4 +262,31 @@ public class InternalContext {
     public interface ContextHolder {
         void setContext(InternalContext context);
     }
+
+    private class ProofOfWorkCallback implements ProofOfWorkEngine.Callback {
+        private final ObjectMessage object;
+        private final ObjectPayload payload;
+
+        private ProofOfWorkCallback(ObjectMessage object, ObjectPayload payload) {
+            this.object = object;
+            this.payload = payload;
+        }
+
+        @Override
+        public void onNonceCalculated(byte[] nonce) {
+            object.setNonce(nonce);
+            messageCallback.proofOfWorkCompleted(payload);
+            if (payload instanceof PlaintextHolder) {
+                Plaintext plaintext = ((PlaintextHolder) payload).getPlaintext();
+                plaintext.setInventoryVector(object.getInventoryVector());
+                plaintext.setStatus(SENT);
+                plaintext.removeLabel(Label.Type.OUTBOX);
+                plaintext.addLabels(messageRepository.getLabels(Label.Type.SENT));
+                messageRepository.save(plaintext);
+            }
+            inventory.storeObject(object);
+            networkHandler.offer(object.getInventoryVector());
+            messageCallback.messageOffered(payload, object.getInventoryVector());
+        }
+    }
 }
diff --git a/domain/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java b/domain/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java
index 0441e6e..380e431 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java
@@ -17,6 +17,7 @@
 package ch.dissem.bitmessage.entity;
 
 import ch.dissem.bitmessage.entity.payload.Pubkey;
+import ch.dissem.bitmessage.entity.payload.Pubkey.Feature;
 import ch.dissem.bitmessage.entity.payload.V4Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
 import ch.dissem.bitmessage.utils.AccessCounter;
@@ -220,4 +221,11 @@ public class BitmessageAddress implements Serializable {
     public void setSubscribed(boolean subscribed) {
         this.subscribed = subscribed;
     }
+
+    public boolean has(Feature feature) {
+        if (pubkey == null || feature == null) {
+            return false;
+        }
+        return feature.isActive(pubkey.getBehaviorBitfield());
+    }
 }
diff --git a/domain/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/domain/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index eb0a60f..34ecd52 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -16,6 +16,7 @@
 
 package ch.dissem.bitmessage.entity;
 
+import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.factory.Factory;
@@ -26,6 +27,8 @@ import ch.dissem.bitmessage.utils.UnixTime;
 import java.io.*;
 import java.util.*;
 
+import static ch.dissem.bitmessage.utils.Singleton.security;
+
 /**
  * The unencrypted message to be sent by 'msg' or 'broadcast'.
  */
@@ -34,7 +37,8 @@ public class Plaintext implements Streamable {
     private final BitmessageAddress from;
     private final long encoding;
     private final byte[] message;
-    private final byte[] ack;
+    private final byte[] ackData;
+    private ObjectMessage ackMessage;
     private Object id;
     private InventoryVector inventoryVector;
     private BitmessageAddress to;
@@ -53,7 +57,13 @@ public class Plaintext implements Streamable {
         to = builder.to;
         encoding = builder.encoding;
         message = builder.message;
-        ack = builder.ack;
+        ackData = builder.ackData;
+        if (builder.ackMessage != null) {
+            ackMessage = Factory.getObjectMessage(
+                    3,
+                    new ByteArrayInputStream(builder.ackMessage),
+                    builder.ackMessage.length);
+        }
         signature = builder.signature;
         status = builder.status;
         sent = builder.sent;
@@ -159,8 +169,15 @@ public class Plaintext implements Streamable {
         Encode.varInt(message.length, out);
         out.write(message);
         if (type == Type.MSG) {
-            Encode.varInt(ack.length, out);
-            out.write(ack);
+            if (to.has(Pubkey.Feature.DOES_ACK)) {
+                ByteArrayOutputStream ack = new ByteArrayOutputStream();
+                ackMessage.write(ack);
+                byte[] data = ack.toByteArray();
+                Encode.varInt(data.length, out);
+                out.write(data);
+            } else {
+                Encode.varInt(0, out);
+            }
         }
         if (includeSignature) {
             if (signature == null) {
@@ -234,7 +251,7 @@ public class Plaintext implements Streamable {
         return Objects.equals(encoding, plaintext.encoding) &&
                 Objects.equals(from, plaintext.from) &&
                 Arrays.equals(message, plaintext.message) &&
-                Arrays.equals(ack, plaintext.ack) &&
+                Arrays.equals(ackData, plaintext.ackData) &&
                 Arrays.equals(to.getRipe(), plaintext.to.getRipe()) &&
                 Arrays.equals(signature, plaintext.signature) &&
                 Objects.equals(status, plaintext.status) &&
@@ -245,21 +262,46 @@ public class Plaintext implements Streamable {
 
     @Override
     public int hashCode() {
-        return Objects.hash(from, encoding, message, ack, to, signature, status, sent, received, labels);
+        return Objects.hash(from, encoding, message, ackData, to, signature, status, sent, received, labels);
     }
 
     public void addLabels(Label... labels) {
         if (labels != null) {
-            Collections.addAll(this.labels, labels);
+            for (Label label : labels) {
+                this.labels.add(label);
+            }
         }
     }
 
     public void addLabels(Collection<Label> labels) {
         if (labels != null) {
-            this.labels.addAll(labels);
+            for (Label label : labels) {
+                this.labels.add(label);
+            }
         }
     }
 
+    public void removeLabel(Label.Type type) {
+        Iterator<Label> iterator = labels.iterator();
+        while (iterator.hasNext()) {
+            Label label = iterator.next();
+            if (label.getType() == type) {
+                iterator.remove();
+            }
+        }
+    }
+
+    public byte[] getAckData() {
+        return ackData;
+    }
+
+    public ObjectMessage getAckMessage() {
+        if (ackMessage == null) {
+            ackMessage = Factory.createAck(this);
+        }
+        return ackMessage;
+    }
+
     public enum Encoding {
         IGNORE(0), TRIVIAL(1), SIMPLE(2);
 
@@ -304,7 +346,8 @@ public class Plaintext implements Streamable {
         private byte[] destinationRipe;
         private long encoding;
         private byte[] message = new byte[0];
-        private byte[] ack = new byte[0];
+        private byte[] ackData;
+        private byte[] ackMessage;
         private byte[] signature;
         private long sent;
         private long received;
@@ -405,7 +448,13 @@ public class Plaintext implements Streamable {
 
         public Builder ack(byte[] ack) {
             if (type != Type.MSG && ack != null) throw new IllegalArgumentException("ack only allowed for msg");
-            this.ack = ack;
+            this.ackMessage = ack;
+            return this;
+        }
+
+        public Builder ackData(byte[] ackData) {
+            if (type != Type.MSG && ackData != null) throw new IllegalArgumentException("ack only allowed for msg");
+            this.ackData = ackData;
             return this;
         }
 
@@ -449,6 +498,9 @@ public class Plaintext implements Streamable {
             if (to == null && type != Type.BROADCAST) {
                 to = new BitmessageAddress(0, 0, destinationRipe);
             }
+            if (type == Type.MSG && ackMessage == null && ackData == null) {
+                ackData = security().randomBytes(32);
+            }
             return new Plaintext(this);
         }
     }
diff --git a/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java b/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java
new file mode 100644
index 0000000..a8308b9
--- /dev/null
+++ b/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java
@@ -0,0 +1,33 @@
+package ch.dissem.bitmessage.entity.payload;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * Created by chrigu on 06.11.15.
+ */
+public class Ack extends ObjectPayload {
+    private final long stream;
+    private final byte[] data;
+
+    public Ack(long version, long stream, byte[] data) {
+        super(version);
+        this.stream = stream;
+        this.data = data;
+    }
+
+    @Override
+    public ObjectType getType() {
+        return ObjectType.MSG;
+    }
+
+    @Override
+    public long getStream() {
+        return stream;
+    }
+
+    @Override
+    public void write(OutputStream out) throws IOException {
+        out.write(data);
+    }
+}
diff --git a/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java b/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
index 1243b32..675bc3d 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
@@ -103,5 +103,9 @@ public abstract class Pubkey extends ObjectPayload {
             }
             return features.toArray(new Feature[features.size()]);
         }
+
+        public boolean isActive(int bitfield) {
+            return (bitfield & bit) != 0;
+        }
     }
 }
diff --git a/domain/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.java b/domain/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.java
index 7c37973..02f0384 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.java
@@ -79,6 +79,7 @@ public class Label implements Serializable {
         INBOX,
         BROADCAST,
         DRAFT,
+        OUTBOX,
         SENT,
         UNREAD,
         TRASH
diff --git a/domain/src/main/java/ch/dissem/bitmessage/factory/Factory.java b/domain/src/main/java/ch/dissem/bitmessage/factory/Factory.java
index 33604ab..135dd93 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/factory/Factory.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/factory/Factory.java
@@ -203,4 +203,11 @@ public class Factory {
             return new V5Broadcast(sendingAddress, plaintext);
         }
     }
+
+    public static ObjectMessage createAck(Plaintext plaintext) {
+        if (plaintext == null || plaintext.getAckData() == null)
+            return null;
+        Ack ack = new Ack(3, plaintext.getFrom().getStream(), plaintext.getAckData());
+        return new ObjectMessage.Builder().payload(ack).build();
+    }
 }

From c31ec7a9e526a5e275952635055d95b8e58dbb32 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Tue, 12 Apr 2016 17:27:19 +0200
Subject: [PATCH 02/20] Fixed problems after merging

---
 .../dissem/bitmessage/DefaultMessageListener.java |  4 ++--
 .../ch/dissem/bitmessage/InternalContext.java     | 15 +++++----------
 .../ch/dissem/bitmessage/entity/Plaintext.java    |  2 +-
 .../ch/dissem/bitmessage/entity/payload/Ack.java  |  0
 .../bitmessage/DefaultMessageListenerTest.java    | 11 ++++++++---
 5 files changed, 16 insertions(+), 16 deletions(-)
 rename {domain => core}/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java (100%)

diff --git a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
index c8eed14..e8be606 100644
--- a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
+++ b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
@@ -165,8 +165,8 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
         listener.receive(msg);
         updatePubkey(msg.getFrom(), msg.getFrom().getPubkey());
 
-        if (msg.getType() == Type.MSG && identity.has(Pubkey.Feature.DOES_ACK)) {
-            ObjectMessage ack = plaintext.getAckMessage();
+        if (msg.getType() == Plaintext.Type.MSG && msg.getTo().has(Pubkey.Feature.DOES_ACK)) {
+            ObjectMessage ack = msg.getAckMessage();
             if (ack != null) {
                 ctx.getInventory().storeObject(ack);
                 ctx.getNetworkHandler().offer(ack.getInventoryVector());
diff --git a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
index 03c6bfc..586adf4 100644
--- a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
@@ -16,14 +16,10 @@
 
 package ch.dissem.bitmessage;
 
-import ch.dissem.bitmessage.entity.BitmessageAddress;
-import ch.dissem.bitmessage.entity.Encrypted;
-import ch.dissem.bitmessage.entity.ObjectMessage;
-import ch.dissem.bitmessage.entity.payload.*;
-import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.entity.*;
 import ch.dissem.bitmessage.entity.payload.*;
 import ch.dissem.bitmessage.entity.valueobject.Label;
+import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.ports.*;
 import ch.dissem.bitmessage.utils.Singleton;
 import ch.dissem.bitmessage.utils.TTL;
@@ -36,7 +32,6 @@ import java.util.Arrays;
 import java.util.TreeSet;
 
 import static ch.dissem.bitmessage.entity.Plaintext.Status.SENT;
-import static ch.dissem.bitmessage.utils.UnixTime.DAY;
 
 /**
  * The internal context should normally only be used for port implementations. If you need it in your client
@@ -182,11 +177,11 @@ public class InternalContext {
             if (payload instanceof Msg && recipient.has(Pubkey.Feature.DOES_ACK)) {
                 ObjectMessage ackMessage = ((Msg) payload).getPlaintext().getAckMessage();
                 messageCallback.proofOfWorkStarted(payload);
-                security.doProofOfWork(ackMessage, networkNonceTrialsPerByte, networkExtraBytes, new ProofOfWorkEngine.Callback() {
+                cryptography.doProofOfWork(ackMessage, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES, new ProofOfWorkEngine.Callback() {
                     @Override
-                    public void onNonceCalculated(byte[] nonce) {
+                    public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
                         object.encrypt(recipient.getPubkey());
-                        proofOfWorkService.doProofOfWork(to, object);
+                        proofOfWorkService.doProofOfWork(recipient, object);
                     }
                 });
             } else {
@@ -318,7 +313,7 @@ public class InternalContext {
         }
 
         @Override
-        public void onNonceCalculated(byte[] nonce) {
+        public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
             object.setNonce(nonce);
             messageCallback.proofOfWorkCompleted(payload);
             if (payload instanceof PlaintextHolder) {
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index 01deca8..c7f23ce 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -175,7 +175,7 @@ public class Plaintext implements Streamable {
         if (type == Type.MSG) {
             if (to.has(Pubkey.Feature.DOES_ACK)) {
                 ByteArrayOutputStream ack = new ByteArrayOutputStream();
-                ackMessage.write(ack);
+                getAckMessage().write(ack);
                 byte[] data = ack.toByteArray();
                 Encode.varInt(data.length, out);
                 out.write(data);
diff --git a/domain/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java
similarity index 100%
rename from domain/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java
rename to core/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java
diff --git a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
index 710bf98..e225924 100644
--- a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
@@ -24,9 +24,7 @@ import ch.dissem.bitmessage.entity.payload.Broadcast;
 import ch.dissem.bitmessage.entity.payload.GetPubkey;
 import ch.dissem.bitmessage.entity.payload.Msg;
 import ch.dissem.bitmessage.factory.Factory;
-import ch.dissem.bitmessage.ports.AddressRepository;
-import ch.dissem.bitmessage.ports.Labeler;
-import ch.dissem.bitmessage.ports.MessageRepository;
+import ch.dissem.bitmessage.ports.*;
 import ch.dissem.bitmessage.utils.Singleton;
 import ch.dissem.bitmessage.utils.TestBase;
 import ch.dissem.bitmessage.utils.TestUtils;
@@ -51,6 +49,10 @@ public class DefaultMessageListenerTest extends TestBase {
     private AddressRepository addressRepo;
     @Mock
     private MessageRepository messageRepo;
+    @Mock
+    private Inventory inventory;
+    @Mock
+    private NetworkHandler networkHandler;
 
     private InternalContext ctx;
     private DefaultMessageListener listener;
@@ -62,6 +64,8 @@ public class DefaultMessageListenerTest extends TestBase {
         Singleton.initialize(new BouncyCryptography());
         when(ctx.getAddressRepository()).thenReturn(addressRepo);
         when(ctx.getMessageRepository()).thenReturn(messageRepo);
+        when(ctx.getInventory()).thenReturn(inventory);
+        when(ctx.getNetworkHandler()).thenReturn(networkHandler);
 
         listener = new DefaultMessageListener(ctx, mock(Labeler.class), mock(BitmessageContext.Listener.class));
     }
@@ -104,6 +108,7 @@ public class DefaultMessageListenerTest extends TestBase {
     public void ensureIncomingMessageIsSaved() throws Exception {
         BitmessageAddress identity = TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8");
         BitmessageAddress contact = new BitmessageAddress(identity.getAddress());
+        contact.setPubkey(identity.getPubkey());
 
         when(addressRepo.getIdentities()).thenReturn(Collections.singletonList(identity));
 

From ddd5826f42c9253ca5a3fc6eba1d41f615e4eb77 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Wed, 13 Apr 2016 07:32:35 +0200
Subject: [PATCH 03/20] Fixed feature bitfield calculation/resolution

---
 .../bitmessage/entity/payload/Pubkey.java      | 11 +++++++----
 .../entity/BitmessageAddressTest.java          | 18 +++++++++++++-----
 .../repository/JdbcAddressRepositoryTest.java  |  5 ++++-
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
index 722f60c..789c64c 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
@@ -76,16 +76,19 @@ public abstract class Pubkey extends ObjectPayload {
          * Receiving node expects that the RIPE hash encoded in their address preceedes the encrypted message data of msg
          * messages bound for them.
          */
-        INCLUDE_DESTINATION(1 << 30),
+        INCLUDE_DESTINATION(30),
         /**
          * If true, the receiving node does send acknowledgements (rather than dropping them).
          */
-        DOES_ACK(1 << 31);
+        DOES_ACK(31);
 
         private int bit;
 
-        Feature(int bit) {
-            this.bit = bit;
+        Feature(int bitNumber) {
+            // The Bitmessage Protocol Specification starts counting at the most significant bit,
+            // thus the slightly awkward calculation.
+            // https://bitmessage.org/wiki/Protocol_specification#Pubkey_bitfield_features
+            this.bit = 1 << (31 - bitNumber);
         }
 
         public static int bitfield(Feature... features) {
diff --git a/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java b/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java
index 9b22589..5d10cdf 100644
--- a/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java
@@ -20,20 +20,25 @@ import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.entity.payload.V4Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
 import ch.dissem.bitmessage.exception.DecryptionFailedException;
-import ch.dissem.bitmessage.utils.Base58;
-import ch.dissem.bitmessage.utils.Bytes;
-import ch.dissem.bitmessage.utils.Strings;
-import ch.dissem.bitmessage.utils.TestUtils;
+import ch.dissem.bitmessage.utils.*;
 import org.junit.Test;
 
 import java.io.IOException;
 import java.util.Arrays;
 
 import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.DOES_ACK;
+import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.INCLUDE_DESTINATION;
 import static ch.dissem.bitmessage.utils.Singleton.security;
 import static org.junit.Assert.*;
 
-public class BitmessageAddressTest {
+public class BitmessageAddressTest extends TestBase {
+    @Test
+    public void ensureFeatureFlagIsCalculatedCorrectly() {
+        assertEquals(1, Pubkey.Feature.bitfield(DOES_ACK));
+        assertEquals(2, Pubkey.Feature.bitfield(INCLUDE_DESTINATION));
+        assertEquals(3, Pubkey.Feature.bitfield(DOES_ACK, INCLUDE_DESTINATION));
+    }
+
     @Test
     public void ensureBase58DecodesCorrectly() {
         assertHexEquals("800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D507A5B8D",
@@ -61,6 +66,7 @@ public class BitmessageAddressTest {
     public void ensureIdentityCanBeCreated() {
         BitmessageAddress address = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000, DOES_ACK));
         assertNotNull(address.getPubkey());
+        assertTrue(address.has(DOES_ACK));
     }
 
     @Test
@@ -90,6 +96,7 @@ public class BitmessageAddressTest {
         }
 
         assertArrayEquals(Bytes.fromHex("007402be6e76c3cb87caa946d0c003a3d4d8e1d5"), pubkey.getRipe());
+        assertTrue(address.has(DOES_ACK));
     }
 
     @Test
@@ -104,6 +111,7 @@ public class BitmessageAddressTest {
         } catch (Exception e) {
             fail(e.getMessage());
         }
+        assertTrue(address.has(DOES_ACK));
     }
 
     @Test
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java
index bd91329..1975d43 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java
@@ -17,12 +17,14 @@
 package ch.dissem.bitmessage.repository;
 
 import ch.dissem.bitmessage.entity.BitmessageAddress;
+import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
 import org.junit.Before;
 import org.junit.Test;
 
 import java.util.List;
 
+import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.DOES_ACK;
 import static org.junit.Assert.*;
 
 public class JdbcAddressRepositoryTest extends TestBase {
@@ -46,7 +48,7 @@ public class JdbcAddressRepositoryTest extends TestBase {
         repo.save(new BitmessageAddress(CONTACT_B));
         repo.save(new BitmessageAddress(CONTACT_C));
 
-        BitmessageAddress identityA = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000));
+        BitmessageAddress identityA = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000, DOES_ACK));
         repo.save(identityA);
         IDENTITY_A = identityA.getAddress();
         BitmessageAddress identityB = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000));
@@ -68,6 +70,7 @@ public class JdbcAddressRepositoryTest extends TestBase {
         assertEquals(4, identity.getVersion());
         assertEquals(identity, repo.findIdentity(identity.getTag()));
         assertNull(repo.findContact(identity.getTag()));
+        assertTrue(identity.has(Pubkey.Feature.DOES_ACK));
     }
 
     @Test

From 61890b3da98c47fd6b0f4dbec16477cb6614a883 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 15 Apr 2016 17:18:11 +0200
Subject: [PATCH 04/20] Some improvements to the application

---
 .../dissem/bitmessage/demo/Application.java   | 67 +++++++++++++++++--
 1 file changed, 60 insertions(+), 7 deletions(-)

diff --git a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
index f3d9579..2c0246e 100644
--- a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
+++ b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
@@ -99,7 +99,7 @@ public class Application {
                         subscriptions();
                         break;
                     case "m":
-                        messages();
+                        labels();
                         break;
                     case "?":
                         info();
@@ -280,22 +280,65 @@ public class Application {
         }
     }
 
-    private void messages() {
+    private void labels() {
+        List<Label> labels = ctx.messages().getLabels();
         String command;
         do {
-            List<Plaintext> messages = ctx.messages().findMessages(Plaintext.Status.RECEIVED);
+            System.out.println();
+            int i = 0;
+            for (Label label : labels) {
+                i++;
+                System.out.println(i + ") " + label + " [" + ctx.messages().countUnread(label) + "]");
+            }
+            System.out.println("a) Archive");
+            System.out.println();
+            System.out.println("c) compose message");
+            System.out.println("s) compose broadcast");
+            System.out.println(COMMAND_BACK);
+
+            command = commandLine.nextCommand();
+            switch (command) {
+                case "a":
+                    messages(null);
+                    break;
+                case "c":
+                    compose(false);
+                    break;
+                case "s":
+                    compose(true);
+                    break;
+                case "b":
+                    return;
+                default:
+                    try {
+                        int index = Integer.parseInt(command) - 1;
+                        messages(labels.get(index));
+                    } catch (NumberFormatException | IndexOutOfBoundsException e) {
+                        System.out.println(ERROR_UNKNOWN_COMMAND);
+                    }
+            }
+        } while (!"b".equalsIgnoreCase(command));
+    }
+
+    private void messages(Label label) {
+        String command;
+        do {
+            List<Plaintext> messages = ctx.messages().findMessages(label);
             System.out.println();
             int i = 0;
             for (Plaintext message : messages) {
                 i++;
-                System.out.println(i + ") From: " + message.getFrom() + "; Subject: " + message.getSubject());
+                System.out.println(i + (message.isUnread() ? ">" : ")") + " From: " + message.getFrom() + "; Subject: " + message.getSubject());
             }
             if (i == 0) {
-                System.out.println("You have no messages.");
+                System.out.println("There are no messages.");
             }
             System.out.println();
             System.out.println("c) compose message");
             System.out.println("s) compose broadcast");
+            if (label.getType() == Label.Type.TRASH) {
+                System.out.println("e) empty trash");
+            }
             System.out.println(COMMAND_BACK);
 
             command = commandLine.nextCommand();
@@ -306,6 +349,8 @@ public class Application {
                 case "s":
                     compose(true);
                     break;
+                case "e":
+                    messages.forEach(ctx.messages()::remove);
                 case "b":
                     return;
                 default:
@@ -328,13 +373,15 @@ public class Application {
         System.out.println(message.getText());
         System.out.println();
         System.out.println(message.getLabels().stream().map(Label::toString).collect(
-                Collectors.joining("Labels: ", ", ", "")));
+                Collectors.joining(", ", "Labels: ", "")));
         System.out.println();
         ctx.labeler().markAsRead(message);
+        ctx.messages().save(message);
         String command;
         do {
             System.out.println("r) reply");
             System.out.println("d) delete");
+            System.out.println("a) archive");
             System.out.println(COMMAND_BACK);
             command = commandLine.nextCommand();
             switch (command) {
@@ -342,7 +389,13 @@ public class Application {
                     compose(message.getTo(), message.getFrom(), "RE: " + message.getSubject());
                     break;
                 case "d":
-                    ctx.messages().remove(message);
+                    ctx.labeler().delete(message);
+                    ctx.messages().save(message);
+                    return;
+                case "a":
+                    ctx.labeler().archive(message);
+                    ctx.messages().save(message);
+                    return;
                 case "b":
                     return;
                 default:

From a0505f5704fb57d61c606e4cb483f31837dd56bc Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Mon, 25 Apr 2016 08:13:46 +0200
Subject: [PATCH 05/20] Minor improvements to the demo Application and a fix
 for when the ACK is empty

---
 .../dissem/bitmessage/entity/Plaintext.java   |  2 +-
 demo/build.gradle                             |  1 +
 .../dissem/bitmessage/demo/Application.java   | 20 +++++++++----------
 .../repository/JdbcMessageRepository.java     |  3 ++-
 4 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index c7f23ce..b34206a 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -62,7 +62,7 @@ public class Plaintext implements Streamable {
         encoding = builder.encoding;
         message = builder.message;
         ackData = builder.ackData;
-        if (builder.ackMessage != null) {
+        if (builder.ackMessage != null && builder.ackMessage.length > 0) {
             ackMessage = Factory.getObjectMessage(
                     3,
                     new ByteArrayInputStream(builder.ackMessage),
diff --git a/demo/build.gradle b/demo/build.gradle
index d87b0f3..c1571ed 100644
--- a/demo/build.gradle
+++ b/demo/build.gradle
@@ -31,6 +31,7 @@ dependencies {
     compile 'org.slf4j:slf4j-simple:1.7.12'
     compile 'args4j:args4j:2.32'
     compile 'com.h2database:h2:1.4.190'
+    compile 'org.apache.commons:commons-lang3:3.4'
     testCompile 'junit:junit:4.11'
     testCompile 'org.mockito:mockito-core:1.10.19'
 }
diff --git a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
index 2c0246e..89b91dc 100644
--- a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
+++ b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
@@ -25,10 +25,10 @@ import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.networking.DefaultNetworkHandler;
 import ch.dissem.bitmessage.ports.MemoryNodeRegistry;
 import ch.dissem.bitmessage.repository.*;
+import org.apache.commons.lang3.text.WordUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.io.UnsupportedEncodingException;
 import java.net.InetAddress;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -56,13 +56,7 @@ public class Application {
                 .networkHandler(new DefaultNetworkHandler())
                 .cryptography(new BouncyCryptography())
                 .port(48444)
-                .listener(plaintext -> {
-                    try {
-                        System.out.println(new String(plaintext.getMessage(), "UTF-8"));
-                    } catch (UnsupportedEncodingException e) {
-                        LOG.error(e.getMessage(), e);
-                    }
-                })
+                .listener(plaintext -> System.out.println("New Message from " + plaintext.getFrom() + ": " + plaintext.getSubject()))
                 .build();
 
         if (syncServer == null) {
@@ -288,7 +282,13 @@ public class Application {
             int i = 0;
             for (Label label : labels) {
                 i++;
-                System.out.println(i + ") " + label + " [" + ctx.messages().countUnread(label) + "]");
+                System.out.print(i + ") " + label);
+                int unread = ctx.messages().countUnread(label);
+                if (unread > 0) {
+                    System.out.println(" [" + unread + "]");
+                } else {
+                    System.out.println();
+                }
             }
             System.out.println("a) Archive");
             System.out.println();
@@ -370,7 +370,7 @@ public class Application {
         System.out.println("To:      " + message.getTo());
         System.out.println("Subject: " + message.getSubject());
         System.out.println();
-        System.out.println(message.getText());
+        System.out.println(WordUtils.wrap(message.getText(), 120));
         System.out.println();
         System.out.println(message.getLabels().stream().map(Label::toString).collect(
                 Collectors.joining(", ", "Labels: ", "")));
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
index e043e7e..8f94d03 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
@@ -105,7 +105,8 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
         try (
                 Connection connection = config.getConnection();
                 Statement stmt = connection.createStatement();
-                ResultSet rs = stmt.executeQuery("SELECT count(*) FROM Message WHERE " + where)
+                ResultSet rs = stmt.executeQuery("SELECT count(*) FROM Message WHERE " + where
+                        + " ORDER BY received DESC")
         ) {
             if (rs.next()) {
                 return rs.getInt(1);

From ea2cd7bf5373c0a73de9ec06980fdc1ddeb60f91 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 29 Apr 2016 15:29:22 +0200
Subject: [PATCH 06/20] Improved labeler to cover all cases, and fixed when
 labels are set while sending (outbox vs sent) Removed message callback with
 both didn't work and is obsolete (use a labeler descendant)

---
 .../bitmessage/BaseMessageCallback.java       | 47 -----------------
 .../dissem/bitmessage/BitmessageContext.java  | 24 ++-------
 .../bitmessage/DefaultMessageListener.java    |  5 +-
 .../ch/dissem/bitmessage/InternalContext.java | 44 +++-------------
 .../ch/dissem/bitmessage/MessageCallback.java | 52 -------------------
 .../dissem/bitmessage/ProofOfWorkService.java |  1 +
 .../bitmessage/ports/DefaultLabeler.java      | 40 +++++++++++---
 .../ch/dissem/bitmessage/ports/Labeler.java   | 14 ++++-
 .../bitmessage/BitmessageContextTest.java     |  1 -
 9 files changed, 58 insertions(+), 170 deletions(-)
 delete mode 100644 core/src/main/java/ch/dissem/bitmessage/BaseMessageCallback.java
 delete mode 100644 core/src/main/java/ch/dissem/bitmessage/MessageCallback.java

diff --git a/core/src/main/java/ch/dissem/bitmessage/BaseMessageCallback.java b/core/src/main/java/ch/dissem/bitmessage/BaseMessageCallback.java
deleted file mode 100644
index bf46b74..0000000
--- a/core/src/main/java/ch/dissem/bitmessage/BaseMessageCallback.java
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright 2016 Christian Basler
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package ch.dissem.bitmessage;
-
-import ch.dissem.bitmessage.entity.payload.ObjectPayload;
-import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
-
-/**
- * Default implementation that doesn't do anything.
- *
- * @author Christian Basler
- */
-public class BaseMessageCallback implements MessageCallback {
-    @Override
-    public void proofOfWorkStarted(ObjectPayload message) {
-        // No op
-    }
-
-    @Override
-    public void proofOfWorkCompleted(ObjectPayload message) {
-        // No op
-    }
-
-    @Override
-    public void messageOffered(ObjectPayload message, InventoryVector iv) {
-        // No op
-    }
-
-    @Override
-    public void messageAcknowledged(InventoryVector iv) {
-        // No op
-    }
-}
diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index c2fb84f..682aa80 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -22,7 +22,6 @@ import ch.dissem.bitmessage.entity.payload.Msg;
 import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.payload.ObjectType;
 import ch.dissem.bitmessage.entity.payload.Pubkey.Feature;
-import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
 import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.exception.DecryptionFailedException;
@@ -37,11 +36,12 @@ import java.net.InetAddress;
 import java.util.List;
 import java.util.Timer;
 import java.util.TimerTask;
-import java.util.concurrent.*;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
 
 import static ch.dissem.bitmessage.InternalContext.NETWORK_EXTRA_BYTES;
 import static ch.dissem.bitmessage.InternalContext.NETWORK_NONCE_TRIALS_PER_BYTE;
-import static ch.dissem.bitmessage.entity.Plaintext.Status.*;
 import static ch.dissem.bitmessage.entity.Plaintext.Type.BROADCAST;
 import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
 import static ch.dissem.bitmessage.utils.UnixTime.*;
@@ -155,8 +155,8 @@ public class BitmessageContext {
                 .from(from)
                 .to(to)
                 .message(subject, message)
-                .labels(messages().getLabels(Label.Type.SENT))
                 .build();
+        labeler().markAsSending(msg);
         send(msg);
     }
 
@@ -171,15 +171,11 @@ public class BitmessageContext {
                 ctx.requestPubkey(to);
             }
             if (to.getPubkey() == null) {
-                msg.setStatus(PUBKEY_REQUESTED);
-                msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.OUTBOX));
                 ctx.getMessageRepository().save(msg);
             }
         }
         if (to == null || to.getPubkey() != null) {
             LOG.info("Sending message.");
-            msg.setStatus(DOING_PROOF_OF_WORK);
-            msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.OUTBOX));
             ctx.getMessageRepository().save(msg);
             ctx.send(
                     msg.getFrom(),
@@ -187,9 +183,6 @@ public class BitmessageContext {
                     wrapInObjectPayload(msg),
                     TTL.msg()
             );
-            msg.setStatus(SENT);
-            msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.SENT));
-            ctx.getMessageRepository().save(msg);
         }
     }
 
@@ -310,7 +303,6 @@ public class BitmessageContext {
         ProofOfWorkRepository proofOfWorkRepository;
         ProofOfWorkEngine proofOfWorkEngine;
         Cryptography cryptography;
-        MessageCallback messageCallback;
         CustomCommandHandler customCommandHandler;
         Labeler labeler;
         Listener listener;
@@ -358,11 +350,6 @@ public class BitmessageContext {
             return this;
         }
 
-        public Builder messageCallback(MessageCallback callback) {
-            this.messageCallback = callback;
-            return this;
-        }
-
         public Builder customCommandHandler(CustomCommandHandler handler) {
             this.customCommandHandler = handler;
             return this;
@@ -429,9 +416,6 @@ public class BitmessageContext {
             if (proofOfWorkEngine == null) {
                 proofOfWorkEngine = new MultiThreadedPOWEngine();
             }
-            if (messageCallback == null) {
-                messageCallback = new BaseMessageCallback();
-            }
             if (labeler == null) {
                 labeler = new DefaultLabeler();
             }
diff --git a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
index e8be606..ce7ab8d 100644
--- a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
+++ b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
@@ -109,7 +109,7 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
         List<Plaintext> messages = ctx.getMessageRepository().findMessages(PUBKEY_REQUESTED, address);
         LOG.info("Sending " + messages.size() + " messages for contact " + address);
         for (Plaintext msg : messages) {
-            msg.setStatus(DOING_PROOF_OF_WORK);
+            ctx.getLabeler().markAsSending(msg);
             ctx.getMessageRepository().save(msg);
             ctx.send(
                     msg.getFrom(),
@@ -117,8 +117,6 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
                     new Msg(msg),
                     +2 * DAY
             );
-            msg.setStatus(SENT);
-            ctx.getMessageRepository().save(msg);
         }
     }
 
@@ -158,7 +156,6 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
     }
 
     protected void receive(InventoryVector iv, Plaintext msg) {
-        msg.setStatus(RECEIVED);
         msg.setInventoryVector(iv);
         labeler.setLabels(msg);
         ctx.getMessageRepository().save(msg);
diff --git a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
index 586adf4..15d6958 100644
--- a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
@@ -18,7 +18,6 @@ package ch.dissem.bitmessage;
 
 import ch.dissem.bitmessage.entity.*;
 import ch.dissem.bitmessage.entity.payload.*;
-import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.ports.*;
 import ch.dissem.bitmessage.utils.Singleton;
@@ -31,8 +30,6 @@ import java.io.IOException;
 import java.util.Arrays;
 import java.util.TreeSet;
 
-import static ch.dissem.bitmessage.entity.Plaintext.Status.SENT;
-
 /**
  * The internal context should normally only be used for port implementations. If you need it in your client
  * implementation, you're either doing something wrong, something very weird, or the BitmessageContext should
@@ -55,9 +52,9 @@ public class InternalContext {
     private final MessageRepository messageRepository;
     private final ProofOfWorkRepository proofOfWorkRepository;
     private final ProofOfWorkEngine proofOfWorkEngine;
-    private final MessageCallback messageCallback;
     private final CustomCommandHandler customCommandHandler;
     private final ProofOfWorkService proofOfWorkService;
+    private final Labeler labeler;
 
     private final TreeSet<Long> streams = new TreeSet<>();
     private final int port;
@@ -76,11 +73,11 @@ public class InternalContext {
         this.proofOfWorkService = new ProofOfWorkService();
         this.proofOfWorkEngine = builder.proofOfWorkEngine;
         this.clientNonce = cryptography.randomNonce();
-        this.messageCallback = builder.messageCallback;
         this.customCommandHandler = builder.customCommandHandler;
         this.port = builder.port;
         this.connectionLimit = builder.connectionLimit;
         this.connectionTTL = builder.connectionTTL;
+        this.labeler = builder.labeler;
 
         Singleton.initialize(cryptography);
 
@@ -96,8 +93,7 @@ public class InternalContext {
         }
 
         init(cryptography, inventory, nodeRegistry, networkHandler, addressRepository, messageRepository,
-                proofOfWorkRepository, proofOfWorkService, proofOfWorkEngine,
-                messageCallback, customCommandHandler, builder.labeler);
+                proofOfWorkRepository, proofOfWorkService, proofOfWorkEngine, customCommandHandler, builder.labeler);
         for (BitmessageAddress identity : addressRepository.getIdentities()) {
             streams.add(identity.getStream());
         }
@@ -147,6 +143,10 @@ public class InternalContext {
         return proofOfWorkService;
     }
 
+    public Labeler getLabeler() {
+        return labeler;
+    }
+
     public long[] getStreams() {
         long[] result = new long[streams.size()];
         int i = 0;
@@ -176,7 +176,6 @@ public class InternalContext {
             }
             if (payload instanceof Msg && recipient.has(Pubkey.Feature.DOES_ACK)) {
                 ObjectMessage ackMessage = ((Msg) payload).getPlaintext().getAckMessage();
-                messageCallback.proofOfWorkStarted(payload);
                 cryptography.doProofOfWork(ackMessage, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES, new ProofOfWorkEngine.Callback() {
                     @Override
                     public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
@@ -208,7 +207,6 @@ public class InternalContext {
                     .build();
             response.sign(identity.getPrivateKey());
             response.encrypt(cryptography.createPublicKey(identity.getPublicDecryptionKey()));
-            messageCallback.proofOfWorkStarted(identity.getPubkey());
             // TODO: remember that the pubkey is just about to be sent, and on which stream!
             proofOfWorkService.doProofOfWork(response);
         } catch (IOException e) {
@@ -245,7 +243,6 @@ public class InternalContext {
                 .expiresTime(expires)
                 .payload(new GetPubkey(contact))
                 .build();
-        messageCallback.proofOfWorkStarted(request.getPayload());
         proofOfWorkService.doProofOfWork(request);
     }
 
@@ -302,31 +299,4 @@ public class InternalContext {
     public interface ContextHolder {
         void setContext(InternalContext context);
     }
-
-    private class ProofOfWorkCallback implements ProofOfWorkEngine.Callback {
-        private final ObjectMessage object;
-        private final ObjectPayload payload;
-
-        private ProofOfWorkCallback(ObjectMessage object, ObjectPayload payload) {
-            this.object = object;
-            this.payload = payload;
-        }
-
-        @Override
-        public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
-            object.setNonce(nonce);
-            messageCallback.proofOfWorkCompleted(payload);
-            if (payload instanceof PlaintextHolder) {
-                Plaintext plaintext = ((PlaintextHolder) payload).getPlaintext();
-                plaintext.setInventoryVector(object.getInventoryVector());
-                plaintext.setStatus(SENT);
-                plaintext.removeLabel(Label.Type.OUTBOX);
-                plaintext.addLabels(messageRepository.getLabels(Label.Type.SENT));
-                messageRepository.save(plaintext);
-            }
-            inventory.storeObject(object);
-            networkHandler.offer(object.getInventoryVector());
-            messageCallback.messageOffered(payload, object.getInventoryVector());
-        }
-    }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/MessageCallback.java b/core/src/main/java/ch/dissem/bitmessage/MessageCallback.java
deleted file mode 100644
index d09ff97..0000000
--- a/core/src/main/java/ch/dissem/bitmessage/MessageCallback.java
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * Copyright 2015 Christian Basler
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package ch.dissem.bitmessage;
-
-import ch.dissem.bitmessage.entity.payload.ObjectPayload;
-import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
-
-/**
- * Callback for message sending events, mostly so the user can be notified when POW is done.
- */
-public interface MessageCallback {
-    /**
-     * Called before calculation of proof of work begins.
-     */
-    void proofOfWorkStarted(ObjectPayload message);
-
-    /**
-     * Called after calculation of proof of work finished.
-     */
-    void proofOfWorkCompleted(ObjectPayload message);
-
-    /**
-     * Called once the message is offered to the network. Please note that this doesn't mean the message was sent,
-     * if the client is not connected to the network it's just stored in the inventory.
-     * <p>
-     * Also, please note that this is where the original payload as well as the {@link InventoryVector} of the sent
-     * message is available. If the callback needs the IV for some reason, it should be retrieved here. (Plaintext
-     * and Broadcast messages will have their IV property set automatically though.)
-     * </p>
-     */
-    void messageOffered(ObjectPayload message, InventoryVector iv);
-
-    /**
-     * This isn't called yet, as ACK messages aren't being processed yet. Also, this is only relevant for Plaintext
-     * messages.
-     */
-    void messageAcknowledged(InventoryVector iv);
-}
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
index 93e461f..98fc9a1 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
@@ -66,6 +66,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
         Plaintext plaintext = messageRepo.getMessage(initialHash);
         if (plaintext != null) {
             plaintext.setInventoryVector(object.getInventoryVector());
+            ctx.getLabeler().markAsSent(plaintext);
             messageRepo.save(plaintext);
         }
         ctx.getInventory().storeObject(object);
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java b/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java
index 1598ce1..4f21b3e 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java
@@ -20,13 +20,14 @@ import ch.dissem.bitmessage.InternalContext;
 import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.entity.valueobject.Label;
 
-import java.util.Iterator;
+import static ch.dissem.bitmessage.entity.Plaintext.Status.*;
 
 public class DefaultLabeler implements Labeler, InternalContext.ContextHolder {
     private InternalContext ctx;
 
     @Override
     public void setLabels(Plaintext msg) {
+        msg.setStatus(RECEIVED);
         if (msg.getType() == Plaintext.Type.BROADCAST) {
             msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.INBOX, Label.Type.BROADCAST, Label.Type.UNREAD));
         } else {
@@ -35,14 +36,37 @@ public class DefaultLabeler implements Labeler, InternalContext.ContextHolder {
     }
 
     @Override
-    public void markAsRead(Plaintext msg) {
-        Iterator<Label> iterator = msg.getLabels().iterator();
-        while (iterator.hasNext()) {
-            Label label = iterator.next();
-            if (label.getType() == Label.Type.UNREAD) {
-                iterator.remove();
-            }
+    public void markAsDraft(Plaintext msg) {
+        msg.setStatus(DRAFT);
+        msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.DRAFT));
+    }
+
+    @Override
+    public void markAsSending(Plaintext msg) {
+        if (msg.getTo() != null || msg.getTo().getPubkey() == null) {
+            msg.setStatus(PUBKEY_REQUESTED);
+        } else {
+            msg.setStatus(DOING_PROOF_OF_WORK);
         }
+        msg.removeLabel(Label.Type.DRAFT);
+        msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.OUTBOX));
+    }
+
+    @Override
+    public void markAsSent(Plaintext msg) {
+        msg.setStatus(SENT);
+        msg.removeLabel(Label.Type.OUTBOX);
+        msg.addLabels(ctx.getMessageRepository().getLabels(Label.Type.SENT));
+    }
+
+    @Override
+    public void markAsAcknowledged(Plaintext msg) {
+        msg.setStatus(SENT_ACKNOWLEDGED);
+    }
+
+    @Override
+    public void markAsRead(Plaintext msg) {
+        msg.removeLabel(Label.Type.UNREAD);
     }
 
     @Override
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java b/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java
index 95febaf..5e52845 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java
@@ -19,7 +19,11 @@ package ch.dissem.bitmessage.ports;
 import ch.dissem.bitmessage.entity.Plaintext;
 
 /**
- * Defines and sets labels
+ * Defines and sets labels. Note that it should also update the status field of a message.
+ * <p>
+ * As the labeler gets called whenever the state of a message changes, it can also be used
+ * as a listener.
+ * </p>
  */
 public interface Labeler {
     /**
@@ -29,6 +33,14 @@ public interface Labeler {
      */
     void setLabels(Plaintext msg);
 
+    void markAsDraft(Plaintext msg);
+
+    void markAsSending(Plaintext msg);
+
+    void markAsSent(Plaintext msg);
+
+    void markAsAcknowledged(Plaintext msg);
+
     void markAsRead(Plaintext msg);
 
     void markAsUnread(Plaintext msg);
diff --git a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
index 7ca0d87..ed095a8 100644
--- a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
@@ -56,7 +56,6 @@ public class BitmessageContextTest {
                 .cryptography(new BouncyCryptography())
                 .inventory(mock(Inventory.class))
                 .listener(listener)
-                .messageCallback(mock(MessageCallback.class))
                 .messageRepo(mock(MessageRepository.class))
                 .networkHandler(mock(NetworkHandler.class))
                 .nodeRegistry(mock(NodeRegistry.class))

From c7594795f00ae23d9be89bf981e7c4429e35b7f6 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Mon, 2 May 2016 11:11:29 +0200
Subject: [PATCH 07/20] Fixed tests & bugs, removed Ack payload type (a
 GenericPayload is now used) - SystemTest don't work yet, sending messages
 seems broken - ProofOfWorkService needs some work, the current solution is a
 hack (and might be the reason above tests are broken)

---
 .../dissem/bitmessage/BitmessageContext.java  |  1 +
 .../ch/dissem/bitmessage/InternalContext.java |  5 +-
 .../bitmessage/entity/ObjectMessage.java      | 29 +++++++++++-
 .../dissem/bitmessage/entity/Plaintext.java   |  4 +-
 .../dissem/bitmessage/entity/payload/Ack.java | 33 -------------
 .../bitmessage/entity/payload/Broadcast.java  | 15 ++++++
 .../entity/payload/GenericPayload.java        |  2 +-
 .../dissem/bitmessage/entity/payload/Msg.java | 16 +++++++
 .../entity/payload/ObjectPayload.java         |  1 +
 .../ch/dissem/bitmessage/factory/Factory.java | 11 +++--
 .../bitmessage/BitmessageContextTest.java     | 46 +++++++++++++++++--
 .../DefaultMessageListenerTest.java           |  1 +
 .../ch/dissem/bitmessage/EncryptionTest.java  |  2 +-
 .../bitmessage/ProofOfWorkServiceTest.java    |  1 +
 .../bitmessage/entity/SerializationTest.java  |  2 +-
 .../ch/dissem/bitmessage/utils/TestUtils.java |  2 +-
 .../bitmessage/security/CryptographyTest.java |  8 ++--
 .../extensions/CryptoCustomMessageTest.java   |  2 +-
 18 files changed, 124 insertions(+), 57 deletions(-)
 delete mode 100644 core/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index 682aa80..b19c303 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -164,6 +164,7 @@ public class BitmessageContext {
         if (msg.getFrom() == null || msg.getFrom().getPrivateKey() == null) {
             throw new IllegalArgumentException("'From' must be an identity, i.e. have a private key.");
         }
+        msg.setStatus(Plaintext.Status.DRAFT);
         BitmessageAddress to = msg.getTo();
         if (to != null) {
             if (to.getPubkey() == null) {
diff --git a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
index 15d6958..58333d5 100644
--- a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
@@ -175,10 +175,13 @@ public class InternalContext {
                 object.sign(from.getPrivateKey());
             }
             if (payload instanceof Msg && recipient.has(Pubkey.Feature.DOES_ACK)) {
-                ObjectMessage ackMessage = ((Msg) payload).getPlaintext().getAckMessage();
+                final ObjectMessage ackMessage = ((Msg) payload).getPlaintext().getAckMessage();
                 cryptography.doProofOfWork(ackMessage, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES, new ProofOfWorkEngine.Callback() {
                     @Override
                     public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
+                        // FIXME: the message gets lost if calculation is cancelled
+                        // (e.g. by terminating the application)
+                        ackMessage.setNonce(nonce);
                         object.encrypt(recipient.getPubkey());
                         proofOfWorkService.doProofOfWork(recipient, object);
                     }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java b/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java
index 68aa5ac..a0878c2 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java
@@ -29,6 +29,8 @@ import ch.dissem.bitmessage.utils.Encode;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Arrays;
+import java.util.Objects;
 
 import static ch.dissem.bitmessage.utils.Singleton.security;
 
@@ -55,7 +57,7 @@ public class ObjectMessage implements MessagePayload {
         expiresTime = builder.expiresTime;
         objectType = builder.objectType;
         version = builder.payload.getVersion();
-        stream = builder.streamNumber;
+        stream = builder.streamNumber > 0 ? builder.streamNumber : builder.payload.getStream();
         payload = builder.payload;
     }
 
@@ -230,4 +232,29 @@ public class ObjectMessage implements MessagePayload {
             return new ObjectMessage(this);
         }
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        ObjectMessage that = (ObjectMessage) o;
+
+        return expiresTime == that.expiresTime &&
+                objectType == that.objectType &&
+                version == that.version &&
+                stream == that.stream &&
+                Objects.equals(payload, that.payload);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = Arrays.hashCode(nonce);
+        result = 31 * result + (int) (expiresTime ^ (expiresTime >>> 32));
+        result = 31 * result + (int) (objectType ^ (objectType >>> 32));
+        result = 31 * result + (int) (version ^ (version >>> 32));
+        result = 31 * result + (int) (stream ^ (stream >>> 32));
+        result = 31 * result + (payload != null ? payload.hashCode() : 0);
+        return result;
+    }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index b34206a..c0a33ef 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -173,7 +173,7 @@ public class Plaintext implements Streamable {
         Encode.varInt(message.length, out);
         out.write(message);
         if (type == Type.MSG) {
-            if (to.has(Pubkey.Feature.DOES_ACK)) {
+            if (to.has(Pubkey.Feature.DOES_ACK) && getAckMessage() != null) {
                 ByteArrayOutputStream ack = new ByteArrayOutputStream();
                 getAckMessage().write(ack);
                 byte[] data = ack.toByteArray();
@@ -255,7 +255,7 @@ public class Plaintext implements Streamable {
         return Objects.equals(encoding, plaintext.encoding) &&
                 Objects.equals(from, plaintext.from) &&
                 Arrays.equals(message, plaintext.message) &&
-                Arrays.equals(ackData, plaintext.ackData) &&
+                Objects.equals(getAckMessage(), plaintext.getAckMessage()) &&
                 Arrays.equals(to.getRipe(), plaintext.to.getRipe()) &&
                 Arrays.equals(signature, plaintext.signature) &&
                 Objects.equals(status, plaintext.status) &&
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java
deleted file mode 100644
index a8308b9..0000000
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Ack.java
+++ /dev/null
@@ -1,33 +0,0 @@
-package ch.dissem.bitmessage.entity.payload;
-
-import java.io.IOException;
-import java.io.OutputStream;
-
-/**
- * Created by chrigu on 06.11.15.
- */
-public class Ack extends ObjectPayload {
-    private final long stream;
-    private final byte[] data;
-
-    public Ack(long version, long stream, byte[] data) {
-        super(version);
-        this.stream = stream;
-        this.data = data;
-    }
-
-    @Override
-    public ObjectType getType() {
-        return ObjectType.MSG;
-    }
-
-    @Override
-    public long getStream() {
-        return stream;
-    }
-
-    @Override
-    public void write(OutputStream out) throws IOException {
-        out.write(data);
-    }
-}
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java
index 7e19e8f..1533a2d 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java
@@ -23,6 +23,7 @@ import ch.dissem.bitmessage.entity.PlaintextHolder;
 import ch.dissem.bitmessage.exception.DecryptionFailedException;
 
 import java.io.IOException;
+import java.util.Objects;
 
 import static ch.dissem.bitmessage.entity.Plaintext.Type.BROADCAST;
 import static ch.dissem.bitmessage.utils.Singleton.security;
@@ -96,4 +97,18 @@ public abstract class Broadcast extends ObjectPayload implements Encrypted, Plai
     public boolean isDecrypted() {
         return plaintext != null;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Broadcast broadcast = (Broadcast) o;
+        return stream == broadcast.stream &&
+                (Objects.equals(encrypted, broadcast.encrypted) || Objects.equals(plaintext, broadcast.plaintext));
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(stream);
+    }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java
index 66cc296..4ae4696 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java
@@ -39,7 +39,7 @@ public class GenericPayload extends ObjectPayload {
         this.data = data;
     }
 
-    public static GenericPayload read(long version, InputStream is, long stream, int length) throws IOException {
+    public static GenericPayload read(long version, long stream, InputStream is, int length) throws IOException {
         return new GenericPayload(version, stream, Decode.bytes(is, length));
     }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java
index 8974ce3..edc4643 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java
@@ -24,6 +24,7 @@ import ch.dissem.bitmessage.exception.DecryptionFailedException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.Objects;
 
 import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
 
@@ -108,4 +109,19 @@ public class Msg extends ObjectPayload implements Encrypted, PlaintextHolder {
         if (encrypted == null) throw new IllegalStateException("Msg must be signed and encrypted before writing it.");
         encrypted.write(out);
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        if (!super.equals(o)) return false;
+        Msg msg = (Msg) o;
+        return stream == msg.stream &&
+                (Objects.equals(encrypted, msg.encrypted) || Objects.equals(plaintext, msg.plaintext));
+    }
+
+    @Override
+    public int hashCode() {
+        return (int) stream;
+    }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java
index 33da28d..a7dbaff 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java
@@ -18,6 +18,7 @@ package ch.dissem.bitmessage.entity.payload;
 
 import ch.dissem.bitmessage.entity.ObjectMessage;
 import ch.dissem.bitmessage.entity.Streamable;
+import sun.reflect.generics.reflectiveObjects.NotImplementedException;
 
 import java.io.IOException;
 import java.io.OutputStream;
diff --git a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
index 48cafff..cfa3229 100644
--- a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
+++ b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
@@ -31,6 +31,7 @@ import java.io.InputStream;
 import java.net.SocketException;
 import java.net.SocketTimeoutException;
 
+import static ch.dissem.bitmessage.entity.payload.ObjectType.MSG;
 import static ch.dissem.bitmessage.utils.Singleton.security;
 
 /**
@@ -155,7 +156,7 @@ public class Factory {
         }
         // fallback: just store the message - we don't really care what it is
         LOG.trace("Unexpected object type: " + objectType);
-        return GenericPayload.read(version, stream, streamNumber, length);
+        return GenericPayload.read(version, streamNumber, stream, length);
     }
 
     private static ObjectPayload parseGetPubkey(long version, long streamNumber, InputStream stream, int length) throws IOException {
@@ -177,7 +178,7 @@ public class Factory {
 
     private static ObjectPayload parsePubkey(long version, long streamNumber, InputStream stream, int length) throws IOException {
         Pubkey pubkey = readPubkey(version, streamNumber, stream, length, true);
-        return pubkey != null ? pubkey : GenericPayload.read(version, stream, streamNumber, length);
+        return pubkey != null ? pubkey : GenericPayload.read(version, streamNumber, stream, length);
     }
 
     private static ObjectPayload parseMsg(long version, long streamNumber, InputStream stream, int length) throws IOException {
@@ -192,7 +193,7 @@ public class Factory {
                 return V5Broadcast.read(stream, streamNumber, length);
             default:
                 LOG.debug("Encountered unknown broadcast version " + version);
-                return GenericPayload.read(version, stream, streamNumber, length);
+                return GenericPayload.read(version, streamNumber, stream, length);
         }
     }
 
@@ -208,7 +209,7 @@ public class Factory {
     public static ObjectMessage createAck(Plaintext plaintext) {
         if (plaintext == null || plaintext.getAckData() == null)
             return null;
-        Ack ack = new Ack(3, plaintext.getFrom().getStream(), plaintext.getAckData());
-        return new ObjectMessage.Builder().payload(ack).build();
+        GenericPayload ack = new GenericPayload(3, plaintext.getFrom().getStream(), plaintext.getAckData());
+        return new ObjectMessage.Builder().objectType(MSG).payload(ack).build();
     }
 }
diff --git a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
index ed095a8..91dd94e 100644
--- a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
@@ -22,19 +22,22 @@ import ch.dissem.bitmessage.entity.ObjectMessage;
 import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.entity.payload.ObjectType;
 import ch.dissem.bitmessage.entity.payload.Pubkey;
+import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.ports.*;
-import ch.dissem.bitmessage.utils.MessageMatchers;
-import ch.dissem.bitmessage.utils.Singleton;
-import ch.dissem.bitmessage.utils.TestUtils;
+import ch.dissem.bitmessage.utils.*;
 import org.hamcrest.BaseMatcher;
 import org.hamcrest.Description;
 import org.junit.Before;
 import org.junit.Test;
 
 import java.util.*;
+import java.util.Collections;
+import java.util.stream.Collectors;
 
 import static ch.dissem.bitmessage.entity.payload.ObjectType.*;
 import static ch.dissem.bitmessage.utils.MessageMatchers.object;
+import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.notNullValue;
 import static org.junit.Assert.*;
@@ -59,9 +62,41 @@ public class BitmessageContextTest {
                 .messageRepo(mock(MessageRepository.class))
                 .networkHandler(mock(NetworkHandler.class))
                 .nodeRegistry(mock(NodeRegistry.class))
-                .powRepo(mock(ProofOfWorkRepository.class))
-                .proofOfWorkEngine(mock(ProofOfWorkEngine.class))
+                .powRepo(spy(new ProofOfWorkRepository() {
+                    Map<InventoryVector, Item> items = new HashMap<>();
+
+                    @Override
+                    public Item getItem(byte[] initialHash) {
+                        return items.get(new InventoryVector(initialHash));
+                    }
+
+                    @Override
+                    public List<byte[]> getItems() {
+                        List<byte[]> result = new LinkedList<>();
+                        for (InventoryVector iv : items.keySet()) {
+                            result.add(iv.getHash());
+                        }
+                        return result;
+                    }
+
+                    @Override
+                    public void putObject(ObjectMessage object, long nonceTrialsPerByte, long extraBytes) {
+                        items.put(new InventoryVector(security().getInitialHash(object)), new Item(object, nonceTrialsPerByte, extraBytes));
+                    }
+
+                    @Override
+                    public void removeObject(byte[] initialHash) {
+                        items.remove(initialHash);
+                    }
+                }))
+                .proofOfWorkEngine(spy(new ProofOfWorkEngine() {
+                    @Override
+                    public void calculateNonce(byte[] initialHash, byte[] target, Callback callback) {
+                        callback.onNonceCalculated(initialHash, new byte[8]);
+                    }
+                }))
                 .build();
+        TTL.msg(2 * MINUTE);
     }
 
     @Test
@@ -161,6 +196,7 @@ public class BitmessageContextTest {
     public void ensureMessageIsSent() throws Exception {
         ctx.send(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"), TestUtils.loadContact(),
                 "Subject", "Message");
+        assertEquals(1, ctx.internals().getProofOfWorkRepository().getItems().size());
         verify(ctx.internals().getProofOfWorkRepository(), timeout(10000).atLeastOnce())
                 .putObject(object(MSG), eq(1000L), eq(1000L));
         verify(ctx.messages(), timeout(10000).atLeastOnce()).save(MessageMatchers.plaintext(Plaintext.Type.MSG));
diff --git a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
index e225924..eacaab2 100644
--- a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
@@ -66,6 +66,7 @@ public class DefaultMessageListenerTest extends TestBase {
         when(ctx.getMessageRepository()).thenReturn(messageRepo);
         when(ctx.getInventory()).thenReturn(inventory);
         when(ctx.getNetworkHandler()).thenReturn(networkHandler);
+        when(ctx.getLabeler()).thenReturn(mock(Labeler.class));
 
         listener = new DefaultMessageListener(ctx, mock(Labeler.class), mock(BitmessageContext.Listener.class));
     }
diff --git a/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java b/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java
index 9a24842..be57e4a 100644
--- a/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java
@@ -42,7 +42,7 @@ public class EncryptionTest extends TestBase {
         PrivateKey privateKey = new PrivateKey(false, 1, 1000, 1000);
         CryptoBox cryptoBox = new CryptoBox(before, privateKey.getPubkey().getEncryptionKey());
 
-        GenericPayload after = GenericPayload.read(0, cryptoBox.decrypt(privateKey.getPrivateEncryptionKey()), 1, 100);
+        GenericPayload after = GenericPayload.read(0, 1, cryptoBox.decrypt(privateKey.getPrivateEncryptionKey()), 100);
 
         assertEquals(before, after);
     }
diff --git a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
index e66beb1..fa58cfe 100644
--- a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
@@ -65,6 +65,7 @@ public class ProofOfWorkServiceTest {
         when(ctx.getInventory()).thenReturn(inventory);
         when(ctx.getNetworkHandler()).thenReturn(networkHandler);
         when(ctx.getMessageRepository()).thenReturn(messageRepo);
+        when(ctx.getLabeler()).thenReturn(mock(Labeler.class));
 
         proofOfWorkService = new ProofOfWorkService();
         proofOfWorkService.setContext(ctx);
diff --git a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
index 5d8777a..aa08475 100644
--- a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
@@ -82,7 +82,7 @@ public class SerializationTest extends TestBase {
                 .from(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"))
                 .to(TestUtils.loadContact())
                 .message("Subject", "Message")
-                .ack("ack".getBytes())
+                .ackData("ack".getBytes())
                 .signature(new byte[0])
                 .build();
         ByteArrayOutputStream out = new ByteArrayOutputStream();
diff --git a/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.java b/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.java
index 770039d..21f85ff 100644
--- a/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.java
+++ b/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.java
@@ -72,7 +72,7 @@ public class TestUtils {
 
     public static BitmessageAddress loadContact() throws IOException, DecryptionFailedException {
         BitmessageAddress address = new BitmessageAddress("BM-2cXxfcSetKnbHJX2Y85rSkaVpsdNUZ5q9h");
-        ObjectMessage object = TestUtils.loadObjectMessage(4, "V4Pubkey.payload");
+        ObjectMessage object = TestUtils.loadObjectMessage(3, "V4Pubkey.payload");
         object.decrypt(address.getPublicDecryptionKey());
         address.setPubkey((V4Pubkey) object.getPayload());
         return address;
diff --git a/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.java b/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.java
index 3e5695c..b0937d3 100644
--- a/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.java
+++ b/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.java
@@ -21,9 +21,7 @@ import java.io.IOException;
 import static ch.dissem.bitmessage.utils.UnixTime.DAY;
 import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 import static org.hamcrest.CoreMatchers.is;
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertThat;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
@@ -82,7 +80,7 @@ public class CryptographyTest {
                 .nonce(new byte[8])
                 .expiresTime(UnixTime.now(+28 * DAY))
                 .objectType(0)
-                .payload(GenericPayload.read(0, new ByteArrayInputStream(new byte[0]), 1, 0))
+                .payload(GenericPayload.read(0, 1, new ByteArrayInputStream(new byte[0]), 0))
                 .build();
         crypto.checkProofOfWork(objectMessage, 1000, 1000);
     }
@@ -93,7 +91,7 @@ public class CryptographyTest {
                 .nonce(new byte[8])
                 .expiresTime(UnixTime.now(+2 * MINUTE))
                 .objectType(0)
-                .payload(GenericPayload.read(0, new ByteArrayInputStream(new byte[0]), 1, 0))
+                .payload(GenericPayload.read(0, 1, new ByteArrayInputStream(new byte[0]), 0))
                 .build();
         final CallbackWaiter<byte[]> waiter = new CallbackWaiter<>();
         crypto.doProofOfWork(objectMessage, 1000, 1000,
diff --git a/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java b/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java
index c1303e3..d451323 100644
--- a/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java
+++ b/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java
@@ -52,7 +52,7 @@ public class CryptoCustomMessageTest extends TestBase {
                 new CryptoCustomMessage.Reader<GenericPayload>() {
                     @Override
                     public GenericPayload read(BitmessageAddress ignore, InputStream in) throws IOException {
-                        return GenericPayload.read(0, in, 1, 100);
+                        return GenericPayload.read(0, 1, in, 100);
                     }
                 });
         GenericPayload payloadAfter = messageAfter.decrypt(sendingIdentity.getPublicDecryptionKey());

From 678a48ac3fc729ff6c472b95e0d0b729f6052db0 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Thu, 5 May 2016 10:50:22 +0200
Subject: [PATCH 08/20] Fixed system test and ProofOfWorkService

---
 .../dissem/bitmessage/BitmessageContext.java  | 30 ++----
 .../bitmessage/DefaultMessageListener.java    |  7 +-
 .../ch/dissem/bitmessage/InternalContext.java | 33 +++----
 .../dissem/bitmessage/ProofOfWorkService.java | 60 ++++++++----
 .../bitmessage/entity/BitmessageAddress.java  | 16 ++--
 .../bitmessage/entity/NetworkMessage.java     |  4 +-
 .../bitmessage/entity/ObjectMessage.java      |  8 +-
 .../dissem/bitmessage/entity/Plaintext.java   |  4 +-
 .../bitmessage/entity/payload/Broadcast.java  |  4 +-
 .../bitmessage/entity/payload/CryptoBox.java  | 24 ++---
 .../bitmessage/entity/payload/Pubkey.java     |  6 +-
 .../entity/valueobject/PrivateKey.java        | 22 ++---
 .../ch/dissem/bitmessage/factory/Factory.java |  6 +-
 .../bitmessage/factory/V3MessageFactory.java  |  4 +-
 .../bitmessage/ports/MessageRepository.java   |  2 +
 .../ports/ProofOfWorkRepository.java          | 14 +++
 .../ch/dissem/bitmessage/utils/Singleton.java |  2 +-
 .../bitmessage/BitmessageContextTest.java     | 18 ++--
 .../DefaultMessageListenerTest.java           |  2 +-
 .../ch/dissem/bitmessage/EncryptionTest.java  |  4 +-
 .../entity/BitmessageAddressTest.java         |  8 +-
 .../bitmessage/entity/SerializationTest.java  |  4 +-
 .../ports/ProofOfWorkEngineTest.java          | 10 +-
 .../extensions/CryptoCustomMessage.java       |  6 +-
 .../extensions/CryptoCustomMessageTest.java   | 10 +-
 .../bitmessage/networking/Connection.java     |  4 +-
 repositories/build.gradle                     |  1 +
 .../repository/JdbcMessageRepository.java     | 18 ++++
 .../repository/JdbcProofOfWorkRepository.java | 66 ++++++++++----
 .../db/migration/V3.1__Update_table_POW.sql   |  2 +
 .../repository/JdbcAddressRepositoryTest.java |  6 +-
 .../repository/JdbcMessageRepositoryTest.java |  8 +-
 .../JdbcProofOfWorkRepositoryTest.java        | 91 ++++++++++++++++++-
 .../ch/dissem/bitmessage/wif/WifExporter.java |  4 +-
 .../ch/dissem/bitmessage/wif/WifImporter.java |  4 +-
 35 files changed, 339 insertions(+), 173 deletions(-)
 create mode 100644 repositories/src/main/resources/db/migration/V3.1__Update_table_POW.sql

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index b19c303..d46c36c 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -18,12 +18,9 @@ package ch.dissem.bitmessage;
 
 import ch.dissem.bitmessage.entity.*;
 import ch.dissem.bitmessage.entity.payload.Broadcast;
-import ch.dissem.bitmessage.entity.payload.Msg;
-import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.payload.ObjectType;
 import ch.dissem.bitmessage.entity.payload.Pubkey.Feature;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
-import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.exception.DecryptionFailedException;
 import ch.dissem.bitmessage.factory.Factory;
 import ch.dissem.bitmessage.ports.*;
@@ -178,23 +175,16 @@ public class BitmessageContext {
         if (to == null || to.getPubkey() != null) {
             LOG.info("Sending message.");
             ctx.getMessageRepository().save(msg);
-            ctx.send(
-                    msg.getFrom(),
-                    to,
-                    wrapInObjectPayload(msg),
-                    TTL.msg()
-            );
-        }
-    }
-
-    private ObjectPayload wrapInObjectPayload(Plaintext msg) {
-        switch (msg.getType()) {
-            case MSG:
-                return new Msg(msg);
-            case BROADCAST:
-                return Factory.getBroadcast(msg);
-            default:
-                throw new ApplicationException("Unknown message type " + msg.getType());
+            if (msg.getType() == MSG) {
+                ctx.send(msg, TTL.msg());
+            } else {
+                ctx.send(
+                        msg.getFrom(),
+                        to,
+                        Factory.getBroadcast(msg),
+                        TTL.msg()
+                );
+            }
         }
     }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
index ce7ab8d..14c405c 100644
--- a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
+++ b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
@@ -111,12 +111,7 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
         for (Plaintext msg : messages) {
             ctx.getLabeler().markAsSending(msg);
             ctx.getMessageRepository().save(msg);
-            ctx.send(
-                    msg.getFrom(),
-                    msg.getTo(),
-                    new Msg(msg),
-                    +2 * DAY
-            );
+            ctx.send(msg, +2 * DAY);
         }
     }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
index 58333d5..884dd16 100644
--- a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
@@ -160,6 +160,15 @@ public class InternalContext {
         return port;
     }
 
+    public void send(final Plaintext plaintext, final long timeToLive) {
+        if (plaintext.getAckMessage() != null) {
+            long expires = UnixTime.now(+timeToLive);
+            proofOfWorkService.doProofOfWorkWithAck(plaintext, expires);
+        } else {
+            send(plaintext.getFrom(), plaintext.getTo(), new Msg(plaintext), timeToLive);
+        }
+    }
+
     public void send(final BitmessageAddress from, BitmessageAddress to, final ObjectPayload payload,
                      final long timeToLive) {
         try {
@@ -174,26 +183,12 @@ public class InternalContext {
             if (object.isSigned()) {
                 object.sign(from.getPrivateKey());
             }
-            if (payload instanceof Msg && recipient.has(Pubkey.Feature.DOES_ACK)) {
-                final ObjectMessage ackMessage = ((Msg) payload).getPlaintext().getAckMessage();
-                cryptography.doProofOfWork(ackMessage, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES, new ProofOfWorkEngine.Callback() {
-                    @Override
-                    public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
-                        // FIXME: the message gets lost if calculation is cancelled
-                        // (e.g. by terminating the application)
-                        ackMessage.setNonce(nonce);
-                        object.encrypt(recipient.getPubkey());
-                        proofOfWorkService.doProofOfWork(recipient, object);
-                    }
-                });
-            } else {
-                if (payload instanceof Broadcast) {
-                    ((Broadcast) payload).encrypt();
-                } else if (payload instanceof Encrypted) {
-                    object.encrypt(recipient.getPubkey());
-                }
-                proofOfWorkService.doProofOfWork(to, object);
+            if (payload instanceof Broadcast) {
+                ((Broadcast) payload).encrypt();
+            } else if (payload instanceof Encrypted) {
+                object.encrypt(recipient.getPubkey());
             }
+            proofOfWorkService.doProofOfWork(to, object);
         } catch (IOException e) {
             throw new ApplicationException(e);
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
index 98fc9a1..6df0cc0 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
@@ -1,14 +1,15 @@
 package ch.dissem.bitmessage;
 
-import ch.dissem.bitmessage.entity.BitmessageAddress;
-import ch.dissem.bitmessage.entity.ObjectMessage;
-import ch.dissem.bitmessage.entity.Plaintext;
-import ch.dissem.bitmessage.entity.PlaintextHolder;
+import ch.dissem.bitmessage.entity.*;
+import ch.dissem.bitmessage.entity.payload.Broadcast;
+import ch.dissem.bitmessage.entity.payload.Msg;
+import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.ports.Cryptography;
 import ch.dissem.bitmessage.ports.MessageRepository;
 import ch.dissem.bitmessage.ports.ProofOfWorkEngine;
 import ch.dissem.bitmessage.ports.ProofOfWorkRepository;
+import ch.dissem.bitmessage.ports.ProofOfWorkRepository.Item;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -16,7 +17,7 @@ import java.util.List;
 
 import static ch.dissem.bitmessage.InternalContext.NETWORK_EXTRA_BYTES;
 import static ch.dissem.bitmessage.InternalContext.NETWORK_NONCE_TRIALS_PER_BYTE;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * @author Christian Basler
@@ -35,7 +36,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
 
         LOG.info("Doing POW for " + items.size() + " tasks.");
         for (byte[] initialHash : items) {
-            ProofOfWorkRepository.Item item = powRepo.getItem(initialHash);
+            Item item = powRepo.getItem(initialHash);
             cryptography.doProofOfWork(item.object, item.nonceTrialsPerByte, item.extraBytes, this);
         }
     }
@@ -59,25 +60,50 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
         cryptography.doProofOfWork(object, nonceTrialsPerByte, extraBytes, this);
     }
 
+    public void doProofOfWorkWithAck(Plaintext plaintext, long expirationTime) {
+        final ObjectMessage ack = plaintext.getAckMessage();
+        Item item = new Item(ack, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES,
+                expirationTime, plaintext);
+        powRepo.putObject(item);
+        cryptography.doProofOfWork(ack, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES, this);
+    }
+
     @Override
     public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
-        ObjectMessage object = powRepo.getItem(initialHash).object;
-        object.setNonce(nonce);
-        Plaintext plaintext = messageRepo.getMessage(initialHash);
-        if (plaintext != null) {
-            plaintext.setInventoryVector(object.getInventoryVector());
-            ctx.getLabeler().markAsSent(plaintext);
-            messageRepo.save(plaintext);
+        Item item = powRepo.getItem(initialHash);
+        if (item.message == null) {
+            ObjectMessage object = powRepo.getItem(initialHash).object;
+            object.setNonce(nonce);
+            Plaintext plaintext = messageRepo.getMessage(initialHash);
+            if (plaintext != null) {
+                plaintext.setInventoryVector(object.getInventoryVector());
+                ctx.getLabeler().markAsSent(plaintext);
+                messageRepo.save(plaintext);
+            }
+            ctx.getInventory().storeObject(object);
+            powRepo.removeObject(initialHash);
+            ctx.getNetworkHandler().offer(object.getInventoryVector());
+        } else {
+            item.message.getAckMessage().setNonce(nonce);
+            final ObjectMessage object = new ObjectMessage.Builder()
+                    .stream(item.message.getStream())
+                    .expiresTime(item.expirationTime)
+                    .payload(new Msg(item.message))
+                    .build();
+            if (object.isSigned()) {
+                object.sign(item.message.getFrom().getPrivateKey());
+            }
+            if (object.getPayload() instanceof Encrypted) {
+                object.encrypt(item.message.getTo().getPubkey());
+            }
+            doProofOfWork(item.message.getTo(), object);
         }
-        ctx.getInventory().storeObject(object);
-        powRepo.removeObject(initialHash);
-        ctx.getNetworkHandler().offer(object.getInventoryVector());
     }
 
     @Override
     public void setContext(InternalContext ctx) {
         this.ctx = ctx;
-        this.cryptography = security();
+        this.cryptography = cryptography();
         this.powRepo = ctx.getProofOfWorkRepository();
         this.messageRepo = ctx.getMessageRepository();
     }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java b/core/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java
index 84b349d..ce199c4 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/BitmessageAddress.java
@@ -37,7 +37,7 @@ import java.util.Objects;
 
 import static ch.dissem.bitmessage.utils.Decode.bytes;
 import static ch.dissem.bitmessage.utils.Decode.varInt;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * A Bitmessage address. Can be a user's private address, an address string without public keys or a recipient's address
@@ -74,19 +74,19 @@ public class BitmessageAddress implements Serializable {
             Encode.varInt(version, os);
             Encode.varInt(stream, os);
             if (version < 4) {
-                byte[] checksum = security().sha512(os.toByteArray(), ripe);
+                byte[] checksum = cryptography().sha512(os.toByteArray(), ripe);
                 this.tag = null;
                 this.publicDecryptionKey = Arrays.copyOfRange(checksum, 0, 32);
             } else {
                 // for tag and decryption key, the checksum has to be created with 0x00 padding
-                byte[] checksum = security().doubleSha512(os.toByteArray(), ripe);
+                byte[] checksum = cryptography().doubleSha512(os.toByteArray(), ripe);
                 this.tag = Arrays.copyOfRange(checksum, 32, 64);
                 this.publicDecryptionKey = Arrays.copyOfRange(checksum, 0, 32);
             }
             // but for the address and its checksum they need to be stripped
             int offset = Bytes.numberOfLeadingZeros(ripe);
             os.write(ripe, offset, ripe.length - offset);
-            byte[] checksum = security().doubleSha512(os.toByteArray());
+            byte[] checksum = cryptography().doubleSha512(os.toByteArray());
             os.write(checksum, 0, 4);
             this.address = "BM-" + Base58.encode(os.toByteArray());
         } catch (IOException e) {
@@ -147,18 +147,18 @@ public class BitmessageAddress implements Serializable {
             this.ripe = Bytes.expand(bytes(in, bytes.length - counter.length() - 4), 20);
 
             // test checksum
-            byte[] checksum = security().doubleSha512(bytes, bytes.length - 4);
+            byte[] checksum = cryptography().doubleSha512(bytes, bytes.length - 4);
             byte[] expectedChecksum = bytes(in, 4);
             for (int i = 0; i < 4; i++) {
                 if (expectedChecksum[i] != checksum[i])
                     throw new IllegalArgumentException("Checksum of address failed");
             }
             if (version < 4) {
-                checksum = security().sha512(Arrays.copyOfRange(bytes, 0, counter.length()), ripe);
+                checksum = cryptography().sha512(Arrays.copyOfRange(bytes, 0, counter.length()), ripe);
                 this.tag = null;
                 this.publicDecryptionKey = Arrays.copyOfRange(checksum, 0, 32);
             } else {
-                checksum = security().doubleSha512(Arrays.copyOfRange(bytes, 0, counter.length()), ripe);
+                checksum = cryptography().doubleSha512(Arrays.copyOfRange(bytes, 0, counter.length()), ripe);
                 this.tag = Arrays.copyOfRange(checksum, 32, 64);
                 this.publicDecryptionKey = Arrays.copyOfRange(checksum, 0, 32);
             }
@@ -173,7 +173,7 @@ public class BitmessageAddress implements Serializable {
             Encode.varInt(version, out);
             Encode.varInt(stream, out);
             out.write(ripe);
-            return Arrays.copyOfRange(security().doubleSha512(out.toByteArray()), 32, 64);
+            return Arrays.copyOfRange(cryptography().doubleSha512(out.toByteArray()), 32, 64);
         } catch (IOException e) {
             throw new ApplicationException(e);
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.java b/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.java
index 347af6c..860c6ed 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.java
@@ -27,7 +27,7 @@ import java.security.GeneralSecurityException;
 import java.security.NoSuchAlgorithmException;
 import java.security.NoSuchProviderException;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * A network message is exchanged between two nodes.
@@ -51,7 +51,7 @@ public class NetworkMessage implements Streamable {
      * First 4 bytes of sha512(payload)
      */
     private byte[] getChecksum(byte[] bytes) throws NoSuchProviderException, NoSuchAlgorithmException {
-        byte[] d = security().sha512(bytes);
+        byte[] d = cryptography().sha512(bytes);
         return new byte[]{d[0], d[1], d[2], d[3]};
     }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java b/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java
index a0878c2..6f74257 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java
@@ -32,7 +32,7 @@ import java.io.OutputStream;
 import java.util.Arrays;
 import java.util.Objects;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * The 'object' command sends an object that is shared throughout the network.
@@ -96,7 +96,7 @@ public class ObjectMessage implements MessagePayload {
 
     public InventoryVector getInventoryVector() {
         return new InventoryVector(
-                Bytes.truncate(security().doubleSha512(nonce, getPayloadBytesWithoutNonce()), 32)
+                Bytes.truncate(cryptography().doubleSha512(nonce, getPayloadBytesWithoutNonce()), 32)
         );
     }
 
@@ -121,7 +121,7 @@ public class ObjectMessage implements MessagePayload {
 
     public void sign(PrivateKey key) {
         if (payload.isSigned()) {
-            payload.setSignature(security().getSignature(getBytesToSign(), key));
+            payload.setSignature(cryptography().getSignature(getBytesToSign(), key));
         }
     }
 
@@ -155,7 +155,7 @@ public class ObjectMessage implements MessagePayload {
 
     public boolean isSignatureValid(Pubkey pubkey) throws IOException {
         if (isEncrypted()) throw new IllegalStateException("Payload must be decrypted first");
-        return security().isSignatureValid(getBytesToSign(), payload.getSignature(), pubkey);
+        return cryptography().isSignatureValid(getBytesToSign(), payload.getSignature(), pubkey);
     }
 
     @Override
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index c0a33ef..a2b66f7 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -28,7 +28,7 @@ import ch.dissem.bitmessage.utils.UnixTime;
 import java.io.*;
 import java.util.*;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * The unencrypted message to be sent by 'msg' or 'broadcast'.
@@ -511,7 +511,7 @@ public class Plaintext implements Streamable {
                 to = new BitmessageAddress(0, 0, destinationRipe);
             }
             if (type == Type.MSG && ackMessage == null && ackData == null) {
-                ackData = security().randomBytes(32);
+                ackData = cryptography().randomBytes(32);
             }
             return new Plaintext(this);
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java
index 1533a2d..a583330 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Broadcast.java
@@ -26,7 +26,7 @@ import java.io.IOException;
 import java.util.Objects;
 
 import static ch.dissem.bitmessage.entity.Plaintext.Type.BROADCAST;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * Users who are subscribed to the sending address will see the message appear in their inbox.
@@ -81,7 +81,7 @@ public abstract class Broadcast extends ObjectPayload implements Encrypted, Plai
     }
 
     public void encrypt() throws IOException {
-        encrypt(security().createPublicKey(plaintext.getFrom().getPublicDecryptionKey()));
+        encrypt(cryptography().createPublicKey(plaintext.getFrom().getPublicDecryptionKey()));
     }
 
     @Override
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.java
index 6609070..89d7bd7 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.java
@@ -27,7 +27,7 @@ import java.io.*;
 import java.util.Arrays;
 
 import static ch.dissem.bitmessage.entity.valueobject.PrivateKey.PRIVATE_KEY_SIZE;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 
 public class CryptoBox implements Streamable {
@@ -50,22 +50,22 @@ public class CryptoBox implements Streamable {
 
         // 1. The destination public key is called K.
         // 2. Generate 16 random bytes using a secure random number generator. Call them IV.
-        initializationVector = security().randomBytes(16);
+        initializationVector = cryptography().randomBytes(16);
 
         // 3. Generate a new random EC key pair with private key called r and public key called R.
-        byte[] r = security().randomBytes(PRIVATE_KEY_SIZE);
-        R = security().createPublicKey(r);
+        byte[] r = cryptography().randomBytes(PRIVATE_KEY_SIZE);
+        R = cryptography().createPublicKey(r);
         // 4. Do an EC point multiply with public key K and private key r. This gives you public key P.
-        byte[] P = security().multiply(K, r);
+        byte[] P = cryptography().multiply(K, r);
         byte[] X = Points.getX(P);
         // 5. Use the X component of public key P and calculate the SHA512 hash H.
-        byte[] H = security().sha512(X);
+        byte[] H = cryptography().sha512(X);
         // 6. The first 32 bytes of H are called key_e and the last 32 bytes are called key_m.
         byte[] key_e = Arrays.copyOfRange(H, 0, 32);
         byte[] key_m = Arrays.copyOfRange(H, 32, 64);
         // 7. Pad the input text to a multiple of 16 bytes, in accordance to PKCS7.
         // 8. Encrypt the data with AES-256-CBC, using IV as initialization vector, key_e as encryption key and the padded input text as payload. Call the output cipher text.
-        encrypted = security().crypt(true, data, key_e, initializationVector);
+        encrypted = cryptography().crypt(true, data, key_e, initializationVector);
         // 9. Calculate a 32 byte MAC with HMACSHA256, using key_m as salt and IV + R + cipher text as data. Call the output MAC.
         mac = calculateMac(key_m);
 
@@ -75,7 +75,7 @@ public class CryptoBox implements Streamable {
     private CryptoBox(Builder builder) {
         initializationVector = builder.initializationVector;
         curveType = builder.curveType;
-        R = security().createPoint(builder.xComponent, builder.yComponent);
+        R = cryptography().createPoint(builder.xComponent, builder.yComponent);
         encrypted = builder.encrypted;
         mac = builder.mac;
     }
@@ -101,9 +101,9 @@ public class CryptoBox implements Streamable {
     public InputStream decrypt(byte[] k) throws DecryptionFailedException {
         // 1. The private key used to decrypt is called k.
         // 2. Do an EC point multiply with private key k and public key R. This gives you public key P.
-        byte[] P = security().multiply(R, k);
+        byte[] P = cryptography().multiply(R, k);
         // 3. Use the X component of public key P and calculate the SHA512 hash H.
-        byte[] H = security().sha512(Arrays.copyOfRange(P, 1, 33));
+        byte[] H = cryptography().sha512(Arrays.copyOfRange(P, 1, 33));
         // 4. The first 32 bytes of H are called key_e and the last 32 bytes are called key_m.
         byte[] key_e = Arrays.copyOfRange(H, 0, 32);
         byte[] key_m = Arrays.copyOfRange(H, 32, 64);
@@ -116,14 +116,14 @@ public class CryptoBox implements Streamable {
 
         // 7. Decrypt the cipher text with AES-256-CBC, using IV as initialization vector, key_e as decryption key
         //    and the cipher text as payload. The output is the padded input text.
-        return new ByteArrayInputStream(security().crypt(false, encrypted, key_e, initializationVector));
+        return new ByteArrayInputStream(cryptography().crypt(false, encrypted, key_e, initializationVector));
     }
 
     private byte[] calculateMac(byte[] key_m) {
         try {
             ByteArrayOutputStream macData = new ByteArrayOutputStream();
             writeWithoutMAC(macData);
-            return security().mac(key_m, macData.toByteArray());
+            return cryptography().mac(key_m, macData.toByteArray());
         } catch (IOException e) {
             throw new ApplicationException(e);
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
index 789c64c..c476bf9 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Pubkey.java
@@ -20,7 +20,7 @@ import java.io.IOException;
 import java.io.OutputStream;
 import java.util.ArrayList;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * Public keys for signing and encryption, the answer to a 'getpubkey' request.
@@ -35,7 +35,7 @@ public abstract class Pubkey extends ObjectPayload {
     }
 
     public static byte[] getRipe(byte[] publicSigningKey, byte[] publicEncryptionKey) {
-        return security().ripemd160(security().sha512(publicSigningKey, publicEncryptionKey));
+        return cryptography().ripemd160(cryptography().sha512(publicSigningKey, publicEncryptionKey));
     }
 
     public abstract byte[] getSigningKey();
@@ -45,7 +45,7 @@ public abstract class Pubkey extends ObjectPayload {
     public abstract int getBehaviorBitfield();
 
     public byte[] getRipe() {
-        return security().ripemd160(security().sha512(getSigningKey(), getEncryptionKey()));
+        return cryptography().ripemd160(cryptography().sha512(getSigningKey(), getEncryptionKey()));
     }
 
     public long getNonceTrialsPerByte() {
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.java b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.java
index b9c3afb..716afc6 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.java
@@ -30,7 +30,7 @@ import java.io.*;
 import java.util.ArrayList;
 import java.util.List;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * Represents a private key. Additional information (stream, version, features, ...) is stored in the accompanying
@@ -53,15 +53,15 @@ public class PrivateKey implements Streamable {
         byte[] pubEK;
         byte[] ripe;
         do {
-            privSK = security().randomBytes(PRIVATE_KEY_SIZE);
-            privEK = security().randomBytes(PRIVATE_KEY_SIZE);
-            pubSK = security().createPublicKey(privSK);
-            pubEK = security().createPublicKey(privEK);
+            privSK = cryptography().randomBytes(PRIVATE_KEY_SIZE);
+            privEK = cryptography().randomBytes(PRIVATE_KEY_SIZE);
+            pubSK = cryptography().createPublicKey(privSK);
+            pubEK = cryptography().createPublicKey(privEK);
             ripe = Pubkey.getRipe(pubSK, pubEK);
         } while (ripe[0] != 0 || (shorter && ripe[1] != 0));
         this.privateSigningKey = privSK;
         this.privateEncryptionKey = privEK;
-        this.pubkey = security().createPubkey(Pubkey.LATEST_VERSION, stream, privateSigningKey, privateEncryptionKey,
+        this.pubkey = cryptography().createPubkey(Pubkey.LATEST_VERSION, stream, privateSigningKey, privateEncryptionKey,
                 nonceTrialsPerByte, extraBytes, features);
     }
 
@@ -118,11 +118,11 @@ public class PrivateKey implements Streamable {
                 long encryptionKeyNonce = nextNonce + 1;
                 byte[] ripe;
                 do {
-                    privEK = Bytes.truncate(security().sha512(seed, Encode.varInt(encryptionKeyNonce)), 32);
-                    privSK = Bytes.truncate(security().sha512(seed, Encode.varInt(signingKeyNonce)), 32);
-                    pubSK = security().createPublicKey(privSK);
-                    pubEK = security().createPublicKey(privEK);
-                    ripe = security().ripemd160(security().sha512(pubSK, pubEK));
+                    privEK = Bytes.truncate(cryptography().sha512(seed, Encode.varInt(encryptionKeyNonce)), 32);
+                    privSK = Bytes.truncate(cryptography().sha512(seed, Encode.varInt(signingKeyNonce)), 32);
+                    pubSK = cryptography().createPublicKey(privSK);
+                    pubEK = cryptography().createPublicKey(privEK);
+                    ripe = cryptography().ripemd160(cryptography().sha512(pubSK, pubEK));
 
                     signingKeyNonce += 2;
                     encryptionKeyNonce += 2;
diff --git a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
index cfa3229..49db9d6 100644
--- a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
+++ b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
@@ -32,7 +32,7 @@ import java.net.SocketException;
 import java.net.SocketTimeoutException;
 
 import static ch.dissem.bitmessage.entity.payload.ObjectType.MSG;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * Creates {@link NetworkMessage} objects from {@link InputStream InputStreams}
@@ -117,8 +117,8 @@ public class Factory {
         BitmessageAddress temp = new BitmessageAddress(address);
         PrivateKey privateKey = new PrivateKey(privateSigningKey, privateEncryptionKey,
                 createPubkey(temp.getVersion(), temp.getStream(),
-                        security().createPublicKey(privateSigningKey),
-                        security().createPublicKey(privateEncryptionKey),
+                        cryptography().createPublicKey(privateSigningKey),
+                        cryptography().createPublicKey(privateEncryptionKey),
                         nonceTrialsPerByte, extraBytes, behaviourBitfield));
         BitmessageAddress result = new BitmessageAddress(privateKey);
         if (!result.getAddress().equals(address)) {
diff --git a/core/src/main/java/ch/dissem/bitmessage/factory/V3MessageFactory.java b/core/src/main/java/ch/dissem/bitmessage/factory/V3MessageFactory.java
index d13e73e..af9839f 100644
--- a/core/src/main/java/ch/dissem/bitmessage/factory/V3MessageFactory.java
+++ b/core/src/main/java/ch/dissem/bitmessage/factory/V3MessageFactory.java
@@ -32,7 +32,7 @@ import java.io.IOException;
 import java.io.InputStream;
 
 import static ch.dissem.bitmessage.entity.NetworkMessage.MAGIC_BYTES;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * Creates protocol v3 network messages from {@link InputStream InputStreams}
@@ -183,7 +183,7 @@ class V3MessageFactory {
     }
 
     private static boolean testChecksum(byte[] checksum, byte[] payload) {
-        byte[] payloadChecksum = security().sha512(payload);
+        byte[] payloadChecksum = cryptography().sha512(payload);
         for (int i = 0; i < checksum.length; i++) {
             if (checksum[i] != payloadChecksum[i]) {
                 return false;
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
index 9e949a7..c4cff5c 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
@@ -30,6 +30,8 @@ public interface MessageRepository {
 
     int countUnread(Label label);
 
+    Plaintext getMessage(Object id);
+
     Plaintext getMessage(byte[] initialHash);
 
     List<Plaintext> findMessages(Label label);
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java b/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java
index 739c172..61dc2ab 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java
@@ -1,6 +1,8 @@
 package ch.dissem.bitmessage.ports;
 
+import ch.dissem.bitmessage.entity.BitmessageAddress;
 import ch.dissem.bitmessage.entity.ObjectMessage;
+import ch.dissem.bitmessage.entity.Plaintext;
 
 import java.util.List;
 
@@ -16,6 +18,8 @@ public interface ProofOfWorkRepository {
 
     void putObject(ObjectMessage object, long nonceTrialsPerByte, long extraBytes);
 
+    void putObject(Item item);
+
     void removeObject(byte[] initialHash);
 
     class Item {
@@ -23,10 +27,20 @@ public interface ProofOfWorkRepository {
         public final long nonceTrialsPerByte;
         public final long extraBytes;
 
+        // Needed for ACK POW calculation
+        public final Long expirationTime;
+        public final Plaintext message;
+
         public Item(ObjectMessage object, long nonceTrialsPerByte, long extraBytes) {
+            this(object, nonceTrialsPerByte, extraBytes, 0, null);
+        }
+
+        public Item(ObjectMessage object, long nonceTrialsPerByte, long extraBytes, long expirationTime, Plaintext message) {
             this.object = object;
             this.nonceTrialsPerByte = nonceTrialsPerByte;
             this.extraBytes = extraBytes;
+            this.expirationTime = expirationTime;
+            this.message = message;
         }
     }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/utils/Singleton.java b/core/src/main/java/ch/dissem/bitmessage/utils/Singleton.java
index a751c65..2eeaa97 100644
--- a/core/src/main/java/ch/dissem/bitmessage/utils/Singleton.java
+++ b/core/src/main/java/ch/dissem/bitmessage/utils/Singleton.java
@@ -30,7 +30,7 @@ public class Singleton {
         }
     }
 
-    public static Cryptography security() {
+    public static Cryptography cryptography() {
         return cryptography;
     }
 }
diff --git a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
index 91dd94e..6e49853 100644
--- a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
@@ -24,19 +24,20 @@ import ch.dissem.bitmessage.entity.payload.ObjectType;
 import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.ports.*;
-import ch.dissem.bitmessage.utils.*;
+import ch.dissem.bitmessage.utils.MessageMatchers;
+import ch.dissem.bitmessage.utils.Singleton;
+import ch.dissem.bitmessage.utils.TTL;
+import ch.dissem.bitmessage.utils.TestUtils;
 import org.hamcrest.BaseMatcher;
 import org.hamcrest.Description;
 import org.junit.Before;
 import org.junit.Test;
 
 import java.util.*;
-import java.util.Collections;
-import java.util.stream.Collectors;
 
 import static ch.dissem.bitmessage.entity.payload.ObjectType.*;
 import static ch.dissem.bitmessage.utils.MessageMatchers.object;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.notNullValue;
@@ -79,9 +80,14 @@ public class BitmessageContextTest {
                         return result;
                     }
 
+                    @Override
+                    public void putObject(Item item) {
+                        items.put(new InventoryVector(cryptography().getInitialHash(item.object)), item);
+                    }
+
                     @Override
                     public void putObject(ObjectMessage object, long nonceTrialsPerByte, long extraBytes) {
-                        items.put(new InventoryVector(security().getInitialHash(object)), new Item(object, nonceTrialsPerByte, extraBytes));
+                        items.put(new InventoryVector(cryptography().getInitialHash(object)), new Item(object, nonceTrialsPerByte, extraBytes));
                     }
 
                     @Override
@@ -196,7 +202,7 @@ public class BitmessageContextTest {
     public void ensureMessageIsSent() throws Exception {
         ctx.send(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"), TestUtils.loadContact(),
                 "Subject", "Message");
-        assertEquals(1, ctx.internals().getProofOfWorkRepository().getItems().size());
+        assertEquals(2, ctx.internals().getProofOfWorkRepository().getItems().size());
         verify(ctx.internals().getProofOfWorkRepository(), timeout(10000).atLeastOnce())
                 .putObject(object(MSG), eq(1000L), eq(1000L));
         verify(ctx.messages(), timeout(10000).atLeastOnce()).save(MessageMatchers.plaintext(Plaintext.Type.MSG));
diff --git a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
index eacaab2..170cb93 100644
--- a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.java
@@ -99,7 +99,7 @@ public class DefaultMessageListenerTest extends TestBase {
                 .payload(identity.getPubkey())
                 .build();
         objectMessage.sign(identity.getPrivateKey());
-        objectMessage.encrypt(Singleton.security().createPublicKey(identity.getPublicDecryptionKey()));
+        objectMessage.encrypt(Singleton.cryptography().createPublicKey(identity.getPublicDecryptionKey()));
         listener.receive(objectMessage);
 
         verify(addressRepo).save(any(BitmessageAddress.class));
diff --git a/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java b/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java
index be57e4a..0a6ee25 100644
--- a/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/EncryptionTest.java
@@ -30,14 +30,14 @@ import org.junit.Test;
 
 import java.io.IOException;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
 public class EncryptionTest extends TestBase {
     @Test
     public void ensureDecryptedDataIsSameAsBeforeEncryption() throws IOException, DecryptionFailedException {
-        GenericPayload before = new GenericPayload(0, 1, security().randomBytes(100));
+        GenericPayload before = new GenericPayload(0, 1, cryptography().randomBytes(100));
 
         PrivateKey privateKey = new PrivateKey(false, 1, 1000, 1000);
         CryptoBox cryptoBox = new CryptoBox(before, privateKey.getPubkey().getEncryptionKey());
diff --git a/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java b/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java
index 5d10cdf..fced84f 100644
--- a/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.java
@@ -28,7 +28,7 @@ import java.util.Arrays;
 
 import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.DOES_ACK;
 import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.INCLUDE_DESTINATION;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.junit.Assert.*;
 
 public class BitmessageAddressTest extends TestBase {
@@ -126,7 +126,7 @@ public class BitmessageAddressTest extends TestBase {
         System.out.println("\n\n" + Strings.hex(privsigningkey) + "\n\n");
 
         BitmessageAddress address = new BitmessageAddress(new PrivateKey(privsigningkey, privencryptionkey,
-                security().createPubkey(3, 1, privsigningkey, privencryptionkey, 320, 14000)));
+                cryptography().createPubkey(3, 1, privsigningkey, privencryptionkey, 320, 14000)));
         assertEquals(address_string, address.getAddress());
     }
 
@@ -136,7 +136,7 @@ public class BitmessageAddressTest extends TestBase {
         byte[] privsigningkey = getSecret("5KMWqfCyJZGFgW6QrnPJ6L9Gatz25B51y7ErgqNr1nXUVbtZbdU");
         byte[] privencryptionkey = getSecret("5JXXWEuhHQEPk414SzEZk1PHDRi8kCuZd895J7EnKeQSahJPxGz");
         BitmessageAddress address = new BitmessageAddress(new PrivateKey(privsigningkey, privencryptionkey,
-                security().createPubkey(4, 1, privsigningkey, privencryptionkey, 320, 14000)));
+                cryptography().createPubkey(4, 1, privsigningkey, privencryptionkey, 320, 14000)));
         assertEquals("BM-2cV5f9EpzaYARxtoruSpa6pDoucSf9ZNke", address.getAddress());
     }
 
@@ -151,7 +151,7 @@ public class BitmessageAddressTest extends TestBase {
         if (bytes.length != 37)
             throw new IOException("Unknown format: 37 bytes expected, but secret " + walletImportFormat + " was " + bytes.length + " long");
 
-        byte[] hash = security().doubleSha256(bytes, 33);
+        byte[] hash = cryptography().doubleSha256(bytes, 33);
         for (int i = 0; i < 4; i++) {
             if (hash[i] != bytes[33 + i]) throw new IOException("Hash check failed for secret " + walletImportFormat);
         }
diff --git a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
index aa08475..26d8a35 100644
--- a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
@@ -30,7 +30,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 
 import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.junit.Assert.*;
 
 public class SerializationTest extends TestBase {
@@ -102,7 +102,7 @@ public class SerializationTest extends TestBase {
     public void ensureNetworkMessageIsSerializedAndDeserializedCorrectly() throws Exception {
         ArrayList<InventoryVector> ivs = new ArrayList<>(50000);
         for (int i = 0; i < 50000; i++) {
-            ivs.add(new InventoryVector(security().randomBytes(32)));
+            ivs.add(new InventoryVector(cryptography().randomBytes(32)));
         }
 
         Inv inv = new Inv.Builder().inventory(ivs).build();
diff --git a/core/src/test/java/ch/dissem/bitmessage/ports/ProofOfWorkEngineTest.java b/core/src/test/java/ch/dissem/bitmessage/ports/ProofOfWorkEngineTest.java
index 1ed4aac..c2efb1f 100644
--- a/core/src/test/java/ch/dissem/bitmessage/ports/ProofOfWorkEngineTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/ports/ProofOfWorkEngineTest.java
@@ -21,7 +21,7 @@ import ch.dissem.bitmessage.utils.CallbackWaiter;
 import ch.dissem.bitmessage.utils.TestBase;
 import org.junit.Test;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.junit.Assert.assertTrue;
 
 public class ProofOfWorkEngineTest extends TestBase {
@@ -36,7 +36,7 @@ public class ProofOfWorkEngineTest extends TestBase {
     }
 
     private void testPOW(ProofOfWorkEngine engine) throws InterruptedException {
-        byte[] initialHash = security().sha512(new byte[]{1, 3, 6, 4});
+        byte[] initialHash = cryptography().sha512(new byte[]{1, 3, 6, 4});
         byte[] target = {0, 0, 0, -1, -1, -1, -1, -1};
 
         final CallbackWaiter<byte[]> waiter1 = new CallbackWaiter<>();
@@ -49,10 +49,10 @@ public class ProofOfWorkEngineTest extends TestBase {
                 });
         byte[] nonce = waiter1.waitForValue();
         System.out.println("Calculating nonce took " + waiter1.getTime() + "ms");
-        assertTrue(Bytes.lt(security().doubleSha512(nonce, initialHash), target, 8));
+        assertTrue(Bytes.lt(cryptography().doubleSha512(nonce, initialHash), target, 8));
 
         // Let's add a second (shorter) run to find possible multi threading issues
-        byte[] initialHash2 = security().sha512(new byte[]{1, 3, 6, 5});
+        byte[] initialHash2 = cryptography().sha512(new byte[]{1, 3, 6, 5});
         byte[] target2 = {0, 0, -1, -1, -1, -1, -1, -1};
 
         final CallbackWaiter<byte[]> waiter2 = new CallbackWaiter<>();
@@ -65,7 +65,7 @@ public class ProofOfWorkEngineTest extends TestBase {
                 });
         byte[] nonce2 = waiter2.waitForValue();
         System.out.println("Calculating nonce took " + waiter2.getTime() + "ms");
-        assertTrue(Bytes.lt(security().doubleSha512(nonce2, initialHash2), target2, 8));
+        assertTrue(Bytes.lt(cryptography().doubleSha512(nonce2, initialHash2), target2, 8));
         assertTrue("Second nonce must be quicker to find", waiter1.getTime() > waiter2.getTime());
     }
 
diff --git a/extensions/src/main/java/ch/dissem/bitmessage/extensions/CryptoCustomMessage.java b/extensions/src/main/java/ch/dissem/bitmessage/extensions/CryptoCustomMessage.java
index 0b5b142..7955e5b 100644
--- a/extensions/src/main/java/ch/dissem/bitmessage/extensions/CryptoCustomMessage.java
+++ b/extensions/src/main/java/ch/dissem/bitmessage/extensions/CryptoCustomMessage.java
@@ -28,7 +28,7 @@ import ch.dissem.bitmessage.utils.Encode;
 import java.io.*;
 
 import static ch.dissem.bitmessage.utils.Decode.*;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * A {@link CustomMessage} implementation that contains signed and encrypted data.
@@ -80,7 +80,7 @@ public class CryptoCustomMessage<T extends Streamable> extends CustomMessage {
         }
 
         data.write(out);
-        Encode.varBytes(security().getSignature(out.toByteArray(), identity.getPrivateKey()), out);
+        Encode.varBytes(cryptography().getSignature(out.toByteArray(), identity.getPrivateKey()), out);
         container = new CryptoBox(out.toByteArray(), publicKey);
     }
 
@@ -138,7 +138,7 @@ public class CryptoCustomMessage<T extends Streamable> extends CustomMessage {
         }
 
         public void checkSignature(Pubkey pubkey) throws IOException, IllegalStateException {
-            if (!security().isSignatureValid(out.toByteArray(), varBytes(wrapped), pubkey)) {
+            if (!cryptography().isSignatureValid(out.toByteArray(), varBytes(wrapped), pubkey)) {
                 throw new IllegalStateException("Signature check failed");
             }
         }
diff --git a/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java b/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java
index d451323..bf0fa6d 100644
--- a/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java
+++ b/extensions/src/test/java/ch/dissem/bitmessage/extensions/CryptoCustomMessageTest.java
@@ -30,7 +30,7 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.junit.Assert.assertEquals;
 
 public class CryptoCustomMessageTest extends TestBase {
@@ -39,9 +39,9 @@ public class CryptoCustomMessageTest extends TestBase {
         PrivateKey privateKey = PrivateKey.read(TestUtils.getResource("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8.privkey"));
         BitmessageAddress sendingIdentity = new BitmessageAddress(privateKey);
 
-        GenericPayload payloadBefore = new GenericPayload(0, 1, security().randomBytes(100));
+        GenericPayload payloadBefore = new GenericPayload(0, 1, cryptography().randomBytes(100));
         CryptoCustomMessage<GenericPayload> messageBefore = new CryptoCustomMessage<>(payloadBefore);
-        messageBefore.signAndEncrypt(sendingIdentity, security().createPublicKey(sendingIdentity.getPublicDecryptionKey()));
+        messageBefore.signAndEncrypt(sendingIdentity, cryptography().createPublicKey(sendingIdentity.getPublicDecryptionKey()));
 
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         messageBefore.write(out);
@@ -65,11 +65,11 @@ public class CryptoCustomMessageTest extends TestBase {
         PrivateKey privateKey = PrivateKey.read(TestUtils.getResource("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8.privkey"));
         final BitmessageAddress sendingIdentity = new BitmessageAddress(privateKey);
 
-        ProofOfWorkRequest requestBefore = new ProofOfWorkRequest(sendingIdentity, security().randomBytes(64),
+        ProofOfWorkRequest requestBefore = new ProofOfWorkRequest(sendingIdentity, cryptography().randomBytes(64),
                 ProofOfWorkRequest.Request.CALCULATE);
 
         CryptoCustomMessage<ProofOfWorkRequest> messageBefore = new CryptoCustomMessage<>(requestBefore);
-        messageBefore.signAndEncrypt(sendingIdentity, security().createPublicKey(sendingIdentity.getPublicDecryptionKey()));
+        messageBefore.signAndEncrypt(sendingIdentity, cryptography().createPublicKey(sendingIdentity.getPublicDecryptionKey()));
 
 
         ByteArrayOutputStream out = new ByteArrayOutputStream();
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java b/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
index 54c8acf..4717675 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
@@ -46,7 +46,7 @@ import static ch.dissem.bitmessage.InternalContext.NETWORK_NONCE_TRIALS_PER_BYTE
 import static ch.dissem.bitmessage.networking.Connection.Mode.CLIENT;
 import static ch.dissem.bitmessage.networking.Connection.Mode.SYNC;
 import static ch.dissem.bitmessage.networking.Connection.State.*;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 
 /**
@@ -249,7 +249,7 @@ class Connection {
         }
         try {
             listener.receive(objectMessage);
-            security().checkProofOfWork(objectMessage, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES);
+            cryptography().checkProofOfWork(objectMessage, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES);
             ctx.getInventory().storeObject(objectMessage);
             // offer object to some random nodes so it gets distributed throughout the network:
             networkHandler.offer(objectMessage.getInventoryVector());
diff --git a/repositories/build.gradle b/repositories/build.gradle
index abb8651..2ab092c 100644
--- a/repositories/build.gradle
+++ b/repositories/build.gradle
@@ -18,5 +18,6 @@ dependencies {
     testCompile 'junit:junit:4.12'
     testCompile 'com.h2database:h2:1.4.190'
     testCompile 'org.mockito:mockito-core:1.10.19'
+    testCompile project(path: ':core', configuration: 'testArtifacts')
     testCompile project(':cryptography-bc')
 }
\ No newline at end of file
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
index 8f94d03..ae1b496 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
@@ -117,6 +117,24 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
         return 0;
     }
 
+    @Override
+    public Plaintext getMessage(Object id) {
+        if (id instanceof Long) {
+            List<Plaintext> plaintexts = find("id=" + id);
+            switch (plaintexts.size()) {
+                case 0:
+                    return null;
+                case 1:
+                    return plaintexts.get(0);
+                default:
+                    throw new ApplicationException("This shouldn't happen, found " + plaintexts.size() +
+                            " messages, one or none was expected");
+            }
+        } else {
+            throw new IllegalArgumentException("Long expected for ID");
+        }
+    }
+
     @Override
     public Plaintext getMessage(byte[] initialHash) {
         List<Plaintext> plaintexts = find("initial_hash=X'" + Strings.hex(initialHash) + "'");
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepository.java
index 0fbb2dc..ac6e69f 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepository.java
@@ -1,6 +1,8 @@
 package ch.dissem.bitmessage.repository;
 
+import ch.dissem.bitmessage.InternalContext;
 import ch.dissem.bitmessage.entity.ObjectMessage;
+import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.factory.Factory;
 import ch.dissem.bitmessage.ports.ProofOfWorkRepository;
@@ -8,18 +10,21 @@ import ch.dissem.bitmessage.utils.Strings;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.sql.*;
 import java.util.LinkedList;
 import java.util.List;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * @author Christian Basler
  */
-public class JdbcProofOfWorkRepository extends JdbcHelper implements ProofOfWorkRepository {
+public class JdbcProofOfWorkRepository extends JdbcHelper implements ProofOfWorkRepository, InternalContext.ContextHolder {
     private static final Logger LOG = LoggerFactory.getLogger(JdbcProofOfWorkRepository.class);
+    private InternalContext ctx;
 
     public JdbcProofOfWorkRepository(JdbcConfig config) {
         super(config);
@@ -30,17 +35,27 @@ public class JdbcProofOfWorkRepository extends JdbcHelper implements ProofOfWork
         try (
                 Connection connection = config.getConnection();
                 PreparedStatement ps = connection.prepareStatement("SELECT data, version, nonce_trials_per_byte, " +
-                        "extra_bytes FROM POW WHERE initial_hash=?")
+                        "extra_bytes, expiration_time, message_id FROM POW WHERE initial_hash=?")
         ) {
             ps.setBytes(1, initialHash);
             try (ResultSet rs = ps.executeQuery()) {
                 if (rs.next()) {
                     Blob data = rs.getBlob("data");
-                    return new Item(
-                            Factory.getObjectMessage(rs.getInt("version"), data.getBinaryStream(), (int) data.length()),
-                            rs.getLong("nonce_trials_per_byte"),
-                            rs.getLong("extra_bytes")
-                    );
+                    if (rs.getObject("message_id") == null) {
+                        return new Item(
+                                Factory.getObjectMessage(rs.getInt("version"), data.getBinaryStream(), (int) data.length()),
+                                rs.getLong("nonce_trials_per_byte"),
+                                rs.getLong("extra_bytes")
+                        );
+                    } else {
+                        return new Item(
+                                Factory.getObjectMessage(rs.getInt("version"), data.getBinaryStream(), (int) data.length()),
+                                rs.getLong("nonce_trials_per_byte"),
+                                rs.getLong("extra_bytes"),
+                                rs.getLong("expiration_time"),
+                                ctx.getMessageRepository().getMessage(rs.getLong("message_id"))
+                        );
+                    }
                 } else {
                     throw new IllegalArgumentException("Object requested that we don't have. Initial hash: " + Strings.hex(initialHash));
                 }
@@ -70,24 +85,38 @@ public class JdbcProofOfWorkRepository extends JdbcHelper implements ProofOfWork
     }
 
     @Override
-    public void putObject(ObjectMessage object, long nonceTrialsPerByte, long extraBytes) {
+    public void putObject(Item item) {
         try (
                 Connection connection = config.getConnection();
                 PreparedStatement ps = connection.prepareStatement("INSERT INTO POW (initial_hash, data, version, " +
-                        "nonce_trials_per_byte, extra_bytes) VALUES (?, ?, ?, ?, ?)")
+                        "nonce_trials_per_byte, extra_bytes, expiration_time, message_id) " +
+                        "VALUES (?, ?, ?, ?, ?, ?, ?)")
         ) {
-            ps.setBytes(1, security().getInitialHash(object));
-            writeBlob(ps, 2, object);
-            ps.setLong(3, object.getVersion());
-            ps.setLong(4, nonceTrialsPerByte);
-            ps.setLong(5, extraBytes);
+            ps.setBytes(1, cryptography().getInitialHash(item.object));
+            writeBlob(ps, 2, item.object);
+            ps.setLong(3, item.object.getVersion());
+            ps.setLong(4, item.nonceTrialsPerByte);
+            ps.setLong(5, item.extraBytes);
+
+            if (item.message == null) {
+                ps.setObject(6, null);
+                ps.setObject(7, null);
+            } else {
+                ps.setLong(6, item.expirationTime);
+                ps.setLong(7, (Long) item.message.getId());
+            }
             ps.executeUpdate();
         } catch (IOException | SQLException e) {
-            LOG.debug("Error storing object of type " + object.getPayload().getClass().getSimpleName(), e);
+            LOG.debug("Error storing object of type " + item.object.getPayload().getClass().getSimpleName(), e);
             throw new ApplicationException(e);
         }
     }
 
+    @Override
+    public void putObject(ObjectMessage object, long nonceTrialsPerByte, long extraBytes) {
+        putObject(new Item(object, nonceTrialsPerByte, extraBytes));
+    }
+
     @Override
     public void removeObject(byte[] initialHash) {
         try (
@@ -100,4 +129,9 @@ public class JdbcProofOfWorkRepository extends JdbcHelper implements ProofOfWork
             LOG.debug(e.getMessage(), e);
         }
     }
+
+    @Override
+    public void setContext(InternalContext context) {
+        this.ctx = context;
+    }
 }
diff --git a/repositories/src/main/resources/db/migration/V3.1__Update_table_POW.sql b/repositories/src/main/resources/db/migration/V3.1__Update_table_POW.sql
new file mode 100644
index 0000000..d67a1b5
--- /dev/null
+++ b/repositories/src/main/resources/db/migration/V3.1__Update_table_POW.sql
@@ -0,0 +1,2 @@
+ALTER TABLE POW ADD COLUMN expiration_time BIGINT;
+ALTER TABLE POW ADD COLUMN message_id BIGINT;
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java
index 1975d43..7f3098b 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcAddressRepositoryTest.java
@@ -68,9 +68,11 @@ public class JdbcAddressRepositoryTest extends TestBase {
     public void testFindIdentity() throws Exception {
         BitmessageAddress identity = new BitmessageAddress(IDENTITY_A);
         assertEquals(4, identity.getVersion());
-        assertEquals(identity, repo.findIdentity(identity.getTag()));
         assertNull(repo.findContact(identity.getTag()));
-        assertTrue(identity.has(Pubkey.Feature.DOES_ACK));
+
+        BitmessageAddress storedIdentity = repo.findIdentity(identity.getTag());
+        assertEquals(identity, storedIdentity);
+        assertTrue(storedIdentity.has(Pubkey.Feature.DOES_ACK));
     }
 
     @Test
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
index 816eafa..81051de 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
@@ -32,7 +32,7 @@ import java.util.Arrays;
 import java.util.List;
 
 import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.*;
 
@@ -54,7 +54,7 @@ public class JdbcMessageRepositoryTest extends TestBase {
         AddressRepository addressRepo = new JdbcAddressRepository(config);
         repo = new JdbcMessageRepository(config);
         new InternalContext(new BitmessageContext.Builder()
-                .cryptography(security())
+                .cryptography(cryptography())
                 .addressRepo(addressRepo)
                 .messageRepo(repo)
         );
@@ -146,7 +146,7 @@ public class JdbcMessageRepositoryTest extends TestBase {
     @Test
     public void testSave() throws Exception {
         Plaintext message = new Plaintext.Builder(MSG)
-                .IV(new InventoryVector(security().randomBytes(32)))
+                .IV(new InventoryVector(cryptography().randomBytes(32)))
                 .from(identity)
                 .to(contactA)
                 .message("Subject", "Message")
@@ -169,7 +169,7 @@ public class JdbcMessageRepositoryTest extends TestBase {
     public void testUpdate() throws Exception {
         List<Plaintext> messages = repo.findMessages(Plaintext.Status.DRAFT, contactA);
         Plaintext message = messages.get(0);
-        message.setInventoryVector(new InventoryVector(security().randomBytes(32)));
+        message.setInventoryVector(new InventoryVector(cryptography().randomBytes(32)));
         repo.save(message);
 
         messages = repo.findMessages(Plaintext.Status.DRAFT, contactA);
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.java b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.java
index c8fbaf0..4396eb5 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.java
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.java
@@ -16,13 +16,24 @@
 
 package ch.dissem.bitmessage.repository;
 
+import ch.dissem.bitmessage.BitmessageContext;
+import ch.dissem.bitmessage.InternalContext;
 import ch.dissem.bitmessage.entity.BitmessageAddress;
 import ch.dissem.bitmessage.entity.ObjectMessage;
+import ch.dissem.bitmessage.entity.Plaintext;
+import ch.dissem.bitmessage.entity.payload.GenericPayload;
 import ch.dissem.bitmessage.entity.payload.GetPubkey;
-import ch.dissem.bitmessage.ports.ProofOfWorkRepository;
+import ch.dissem.bitmessage.ports.AddressRepository;
+import ch.dissem.bitmessage.ports.MessageRepository;
+import ch.dissem.bitmessage.ports.ProofOfWorkRepository.Item;
+import ch.dissem.bitmessage.utils.TestUtils;
+import ch.dissem.bitmessage.utils.UnixTime;
 import org.junit.Before;
 import org.junit.Test;
 
+import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
+import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
@@ -33,17 +44,51 @@ import static org.junit.Assert.assertTrue;
 public class JdbcProofOfWorkRepositoryTest extends TestBase {
     private TestJdbcConfig config;
     private JdbcProofOfWorkRepository repo;
+    private AddressRepository addressRepo;
+    private MessageRepository messageRepo;
+
+    private byte[] initialHash1;
+    private byte[] initialHash2;
 
     @Before
     public void setUp() throws Exception {
         config = new TestJdbcConfig();
         config.reset();
 
+        addressRepo = new JdbcAddressRepository(config);
+        messageRepo = new JdbcMessageRepository(config);
         repo = new JdbcProofOfWorkRepository(config);
+        InternalContext ctx = new InternalContext(new BitmessageContext.Builder()
+                .addressRepo(addressRepo)
+                .messageRepo(messageRepo)
+                .powRepo(repo)
+                .cryptography(cryptography())
+        );
 
         repo.putObject(new ObjectMessage.Builder()
                         .payload(new GetPubkey(new BitmessageAddress("BM-2DAjcCFrqFrp88FUxExhJ9kPqHdunQmiyn"))).build(),
                 1000, 1000);
+        initialHash1 = repo.getItems().get(0);
+
+        BitmessageAddress sender = TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8");
+        BitmessageAddress recipient = TestUtils.loadContact();
+        addressRepo.save(sender);
+        addressRepo.save(recipient);
+        Plaintext plaintext = new Plaintext.Builder(MSG)
+                .ackData(cryptography().randomBytes(32))
+                .from(sender)
+                .to(recipient)
+                .message("Subject", "Message")
+                .status(Plaintext.Status.DOING_PROOF_OF_WORK)
+                .build();
+        messageRepo.save(plaintext);
+        initialHash2 = cryptography().getInitialHash(plaintext.getAckMessage());
+        repo.putObject(new Item(
+                plaintext.getAckMessage(),
+                1000, 1000,
+                UnixTime.now(+10 * MINUTE),
+                plaintext
+        ));
     }
 
     @Test
@@ -55,16 +100,52 @@ public class JdbcProofOfWorkRepositoryTest extends TestBase {
         assertThat(repo.getItems().size(), is(sizeBefore + 1));
     }
 
+    @Test
+    public void ensureAckObjectsAreStored() throws Exception {
+        int sizeBefore = repo.getItems().size();
+        BitmessageAddress sender = TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8");
+        BitmessageAddress recipient = TestUtils.loadContact();
+        addressRepo.save(sender);
+        addressRepo.save(recipient);
+        Plaintext plaintext = new Plaintext.Builder(MSG)
+                .ackData(cryptography().randomBytes(32))
+                .from(sender)
+                .to(recipient)
+                .message("Subject", "Message")
+                .status(Plaintext.Status.DOING_PROOF_OF_WORK)
+                .build();
+        messageRepo.save(plaintext);
+        repo.putObject(new Item(
+                plaintext.getAckMessage(),
+                1000, 1000,
+                UnixTime.now(+10 * MINUTE),
+                plaintext
+        ));
+        assertThat(repo.getItems().size(), is(sizeBefore + 1));
+    }
+
     @Test
     public void ensureItemCanBeRetrieved() {
-        byte[] initialHash = repo.getItems().get(0);
-        ProofOfWorkRepository.Item item = repo.getItem(initialHash);
+        Item item = repo.getItem(initialHash1);
         assertThat(item, notNullValue());
         assertThat(item.object.getPayload(), instanceOf(GetPubkey.class));
         assertThat(item.nonceTrialsPerByte, is(1000L));
         assertThat(item.extraBytes, is(1000L));
     }
 
+    @Test
+    public void ensureAckItemCanBeRetrieved() {
+        Item item = repo.getItem(initialHash2);
+        assertThat(item, notNullValue());
+        assertThat(item.object.getPayload(), instanceOf(GenericPayload.class));
+        assertThat(item.nonceTrialsPerByte, is(1000L));
+        assertThat(item.extraBytes, is(1000L));
+        assertThat(item.expirationTime, not(0));
+        assertThat(item.message, notNullValue());
+        assertThat(item.message.getFrom().getPrivateKey(), notNullValue());
+        assertThat(item.message.getTo().getPubkey(), notNullValue());
+    }
+
     @Test(expected = RuntimeException.class)
     public void ensureRetrievingNonexistingItemThrowsException() {
         repo.getItem(new byte[0]);
@@ -72,8 +153,8 @@ public class JdbcProofOfWorkRepositoryTest extends TestBase {
 
     @Test
     public void ensureItemCanBeDeleted() {
-        byte[] initialHash = repo.getItems().get(0);
-        repo.removeObject(initialHash);
+        repo.removeObject(initialHash1);
+        repo.removeObject(initialHash2);
         assertTrue(repo.getItems().isEmpty());
     }
 
diff --git a/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.java b/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.java
index ad6098e..3f4b370 100644
--- a/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.java
+++ b/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.java
@@ -27,7 +27,7 @@ import java.io.*;
 import java.util.Collection;
 
 import static ch.dissem.bitmessage.entity.valueobject.PrivateKey.PRIVATE_KEY_SIZE;
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * @author Christian Basler
@@ -77,7 +77,7 @@ public class WifExporter {
         byte[] result = new byte[37];
         result[0] = (byte) 0x80;
         System.arraycopy(privateKey, 0, result, 1, PRIVATE_KEY_SIZE);
-        byte[] hash = security().doubleSha256(result, PRIVATE_KEY_SIZE + 1);
+        byte[] hash = cryptography().doubleSha256(result, PRIVATE_KEY_SIZE + 1);
         System.arraycopy(hash, 0, result, PRIVATE_KEY_SIZE + 1, 4);
         return Base58.encode(result);
     }
diff --git a/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.java b/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.java
index 1bd6bcd..f5a8ddc 100644
--- a/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.java
+++ b/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.java
@@ -31,7 +31,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map.Entry;
 
-import static ch.dissem.bitmessage.utils.Singleton.security;
+import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
 /**
  * @author Christian Basler
@@ -87,7 +87,7 @@ public class WifImporter {
             throw new IOException("Unknown format: " + WIF_SECRET_LENGTH +
                     " bytes expected, but secret " + walletImportFormat + " was " + bytes.length + " long");
 
-        byte[] hash = security().doubleSha256(bytes, 33);
+        byte[] hash = cryptography().doubleSha256(bytes, 33);
         for (int i = 0; i < 4; i++) {
             if (hash[i] != bytes[33 + i]) throw new IOException("Hash check failed for secret " + walletImportFormat);
         }

From 4f0b2cb8f86cfa85495de1099a1051900ba554af Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 6 May 2016 14:13:39 +0200
Subject: [PATCH 09/20] Fixed system test (this time for real)

---
 .../dissem/bitmessage/BitmessageContext.java  |  3 +-
 .../bitmessage/DefaultMessageListener.java    |  3 +-
 .../dissem/bitmessage/ProofOfWorkService.java |  2 -
 .../bitmessage/ports/DefaultLabeler.java      |  2 +-
 .../ports/ProofOfWorkRepository.java          |  1 -
 .../java/ch/dissem/bitmessage/SystemTest.java | 96 ++++++++++++++++++-
 6 files changed, 97 insertions(+), 10 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index d46c36c..23e8eff 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -153,7 +153,6 @@ public class BitmessageContext {
                 .to(to)
                 .message(subject, message)
                 .build();
-        labeler().markAsSending(msg);
         send(msg);
     }
 
@@ -161,7 +160,7 @@ public class BitmessageContext {
         if (msg.getFrom() == null || msg.getFrom().getPrivateKey() == null) {
             throw new IllegalArgumentException("'From' must be an identity, i.e. have a private key.");
         }
-        msg.setStatus(Plaintext.Status.DRAFT);
+        labeler().markAsSending(msg);
         BitmessageAddress to = msg.getTo();
         if (to != null) {
             if (to.getPubkey() == null) {
diff --git a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
index 14c405c..eb27dd9 100644
--- a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
+++ b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
@@ -24,6 +24,7 @@ import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.exception.DecryptionFailedException;
 import ch.dissem.bitmessage.ports.Labeler;
 import ch.dissem.bitmessage.ports.NetworkHandler;
+import ch.dissem.bitmessage.utils.TTL;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -111,7 +112,7 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
         for (Plaintext msg : messages) {
             ctx.getLabeler().markAsSending(msg);
             ctx.getMessageRepository().save(msg);
-            ctx.send(msg, +2 * DAY);
+            ctx.send(msg, TTL.msg());
         }
     }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
index 6df0cc0..e886c22 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
@@ -1,9 +1,7 @@
 package ch.dissem.bitmessage;
 
 import ch.dissem.bitmessage.entity.*;
-import ch.dissem.bitmessage.entity.payload.Broadcast;
 import ch.dissem.bitmessage.entity.payload.Msg;
-import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.ports.Cryptography;
 import ch.dissem.bitmessage.ports.MessageRepository;
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java b/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java
index 4f21b3e..e4c2105 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.java
@@ -43,7 +43,7 @@ public class DefaultLabeler implements Labeler, InternalContext.ContextHolder {
 
     @Override
     public void markAsSending(Plaintext msg) {
-        if (msg.getTo() != null || msg.getTo().getPubkey() == null) {
+        if (msg.getTo() != null && msg.getTo().getPubkey() == null) {
             msg.setStatus(PUBKEY_REQUESTED);
         } else {
             msg.setStatus(DOING_PROOF_OF_WORK);
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java b/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java
index 61dc2ab..b27a05d 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.java
@@ -1,6 +1,5 @@
 package ch.dissem.bitmessage.ports;
 
-import ch.dissem.bitmessage.entity.BitmessageAddress;
 import ch.dissem.bitmessage.entity.ObjectMessage;
 import ch.dissem.bitmessage.entity.Plaintext;
 
diff --git a/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java b/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
index 06b6628..6751819 100644
--- a/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
+++ b/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
@@ -4,13 +4,19 @@ import ch.dissem.bitmessage.cryptography.bc.BouncyCryptography;
 import ch.dissem.bitmessage.entity.BitmessageAddress;
 import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.networking.DefaultNetworkHandler;
+import ch.dissem.bitmessage.ports.DefaultLabeler;
 import ch.dissem.bitmessage.repository.*;
 import ch.dissem.bitmessage.utils.TTL;
-import org.junit.*;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 
+import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.DOES_ACK;
 import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertThat;
@@ -47,9 +53,10 @@ public class SystemTest {
                 .networkHandler(new DefaultNetworkHandler())
                 .cryptography(new BouncyCryptography())
                 .listener(aliceListener)
+                .labeler(new DebugLabeler("Alice"))
                 .build();
         alice.startup();
-        aliceIdentity = alice.createIdentity(false);
+        aliceIdentity = alice.createIdentity(false, DOES_ACK);
 
         JdbcConfig bobDB = new JdbcConfig("jdbc:h2:mem:bob;DB_CLOSE_DELAY=-1", "sa", "");
         bob = new BitmessageContext.Builder()
@@ -62,9 +69,13 @@ public class SystemTest {
                 .networkHandler(new DefaultNetworkHandler())
                 .cryptography(new BouncyCryptography())
                 .listener(bobListener)
+                .labeler(new DebugLabeler("Bob"))
                 .build();
         bob.startup();
-        bobIdentity = bob.createIdentity(false);
+        bobIdentity = bob.createIdentity(false, DOES_ACK);
+
+        ((DebugLabeler) alice.labeler()).init(aliceIdentity, bobIdentity);
+        ((DebugLabeler) bob.labeler()).init(aliceIdentity, bobIdentity);
     }
 
     @After
@@ -95,4 +106,83 @@ public class SystemTest {
         assertThat(plaintext.getType(), equalTo(Plaintext.Type.BROADCAST));
         assertThat(plaintext.getText(), equalTo(originalMessage));
     }
+
+    private static class DebugLabeler extends DefaultLabeler {
+        private final Logger LOG = LoggerFactory.getLogger("Labeler");
+        final String name;
+        String alice;
+        String bob;
+
+        private DebugLabeler(String name) {
+            this.name = name;
+        }
+
+        private void init(BitmessageAddress alice, BitmessageAddress bob) {
+            this.alice = alice.getAddress();
+            this.bob = bob.getAddress();
+        }
+
+        @Override
+        public void setLabels(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Received");
+            super.setLabels(msg);
+        }
+
+        @Override
+        public void markAsDraft(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Draft");
+            super.markAsDraft(msg);
+        }
+
+        @Override
+        public void markAsSending(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Sending");
+            super.markAsSending(msg);
+        }
+
+        @Override
+        public void markAsSent(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Sent");
+            super.markAsSent(msg);
+        }
+
+        @Override
+        public void markAsAcknowledged(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Acknowledged");
+            super.markAsAcknowledged(msg);
+        }
+
+        @Override
+        public void markAsRead(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Read");
+            super.markAsRead(msg);
+        }
+
+        @Override
+        public void markAsUnread(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Unread");
+            super.markAsUnread(msg);
+        }
+
+        @Override
+        public void delete(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Cleared");
+            super.delete(msg);
+        }
+
+        @Override
+        public void archive(Plaintext msg) {
+            LOG.info(name + ": From " + name(msg.getFrom()) + ": Archived");
+            super.archive(msg);
+        }
+
+        private String name(BitmessageAddress address) {
+            if (alice.equals(address.getAddress()))
+                return "Alice";
+            else if (bob.equals(address.getAddress()))
+                return "Bob";
+            else
+                return "Unknown (" + address.getAddress() + ")";
+        }
+    }
 }

From de8f04e22acbe5a1ffe77d099c9040e89f15ebdc Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 6 May 2016 17:29:39 +0200
Subject: [PATCH 10/20] Added warning to Labeler for developers who want to
 implement it.

---
 core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java b/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java
index 5e52845..e79bee2 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/Labeler.java
@@ -20,6 +20,8 @@ import ch.dissem.bitmessage.entity.Plaintext;
 
 /**
  * Defines and sets labels. Note that it should also update the status field of a message.
+ * Generally it's highly advised to override the {@link DefaultLabeler} whenever possible,
+ * instead of directly implementing the interface.
  * <p>
  * As the labeler gets called whenever the state of a message changes, it can also be used
  * as a listener.
@@ -35,6 +37,10 @@ public interface Labeler {
 
     void markAsDraft(Plaintext msg);
 
+    /**
+     * It is paramount that this methods marks the {@link Plaintext} object with status
+     * {@link Plaintext.Status#PUBKEY_REQUESTED} (see {@link DefaultLabeler})
+     */
     void markAsSending(Plaintext msg);
 
     void markAsSent(Plaintext msg);

From 05d9ea93d266216933f751b0c8b0f83a076c2599 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 6 May 2016 19:39:39 +0200
Subject: [PATCH 11/20] Acknowledgments are now returned, received, and the
 message (Plaintext object) updated -> no logic to resend messages yet

---
 .../dissem/bitmessage/BitmessageContext.java  | 12 ++-----
 .../bitmessage/DefaultMessageListener.java    | 17 ++++++++--
 .../dissem/bitmessage/ProofOfWorkService.java | 23 +++++++++----
 .../dissem/bitmessage/entity/Plaintext.java   |  3 +-
 .../entity/payload/GenericPayload.java        |  4 +++
 .../dissem/bitmessage/entity/payload/Msg.java |  1 +
 .../ch/dissem/bitmessage/factory/Factory.java |  4 ++-
 .../bitmessage/ports/MessageRepository.java   |  2 ++
 .../java/ch/dissem/bitmessage/SystemTest.java |  9 +++++-
 .../bitmessage/repository/JdbcHelper.java     | 10 ++++++
 .../repository/JdbcMessageRepository.java     | 32 +++++++++----------
 .../migration/V3.2__Update_table_message.sql  |  1 +
 12 files changed, 79 insertions(+), 39 deletions(-)
 create mode 100644 repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index 23e8eff..2307958 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -31,8 +31,6 @@ import org.slf4j.LoggerFactory;
 
 import java.net.InetAddress;
 import java.util.List;
-import java.util.Timer;
-import java.util.TimerTask;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
@@ -71,16 +69,10 @@ public class BitmessageContext {
     private BitmessageContext(Builder builder) {
         ctx = new InternalContext(builder);
         labeler = builder.labeler;
+        ctx.getProofOfWorkService().doMissingProofOfWork();
+
         networkListener = new DefaultMessageListener(ctx, labeler, builder.listener);
-
         sendPubkeyOnIdentityCreation = builder.sendPubkeyOnIdentityCreation;
-
-        new Timer().schedule(new TimerTask() {
-            @Override
-            public void run() {
-                ctx.getProofOfWorkService().doMissingProofOfWork();
-            }
-        }, 30_000); // After 30 seconds
     }
 
     public AddressRepository addresses() {
diff --git a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
index eb27dd9..05961e4 100644
--- a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
+++ b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
@@ -48,9 +48,12 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
     }
 
     @Override
+    @SuppressWarnings("ConstantConditions")
     public void receive(ObjectMessage object) throws IOException {
         ObjectPayload payload = object.getPayload();
-        if (payload.getType() == null) return;
+        if (payload.getType() == null && payload instanceof GenericPayload) {
+            receive((GenericPayload) payload);
+        }
 
         switch (payload.getType()) {
             case GET_PUBKEY: {
@@ -125,7 +128,7 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
                 if (!object.isSignatureValid(plaintext.getFrom().getPubkey())) {
                     LOG.warn("Msg with IV " + object.getInventoryVector() + " was successfully decrypted, but signature check failed. Ignoring.");
                 } else {
-                    receive(object.getInventoryVector(), msg.getPlaintext());
+                    receive(object.getInventoryVector(), plaintext);
                 }
                 break;
             } catch (DecryptionFailedException ignore) {
@@ -133,6 +136,16 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
         }
     }
 
+    protected void receive(GenericPayload ack) {
+        if (ack.getData().length == Msg.ACK_LENGTH) {
+            Plaintext msg = ctx.getMessageRepository().getMessageForAck(ack.getData());
+            if (msg != null) {
+                ctx.getLabeler().markAsAcknowledged(msg);
+                ctx.getMessageRepository().save(msg);
+            }
+        }
+    }
+
     protected void receive(ObjectMessage object, Broadcast broadcast) throws IOException {
         byte[] tag = broadcast instanceof V5Broadcast ? ((V5Broadcast) broadcast).getTag() : null;
         for (BitmessageAddress subscription : ctx.getAddressRepository().getSubscriptions(broadcast.getVersion())) {
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
index e886c22..d242b79 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
@@ -12,6 +12,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.util.List;
+import java.util.Timer;
+import java.util.TimerTask;
 
 import static ch.dissem.bitmessage.InternalContext.NETWORK_EXTRA_BYTES;
 import static ch.dissem.bitmessage.InternalContext.NETWORK_NONCE_TRIALS_PER_BYTE;
@@ -29,14 +31,21 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
     private MessageRepository messageRepo;
 
     public void doMissingProofOfWork() {
-        List<byte[]> items = powRepo.getItems();
+        final List<byte[]> items = powRepo.getItems();
         if (items.isEmpty()) return;
 
-        LOG.info("Doing POW for " + items.size() + " tasks.");
-        for (byte[] initialHash : items) {
-            Item item = powRepo.getItem(initialHash);
-            cryptography.doProofOfWork(item.object, item.nonceTrialsPerByte, item.extraBytes, this);
-        }
+        // Wait for 30 seconds, to let the application start up before putting heavy load on the CPU
+        new Timer().schedule(new TimerTask() {
+            @Override
+            public void run() {
+                LOG.info("Doing POW for " + items.size() + " tasks.");
+                for (byte[] initialHash : items) {
+                    Item item = powRepo.getItem(initialHash);
+                    cryptography.doProofOfWork(item.object, item.nonceTrialsPerByte, item.extraBytes,
+                            ProofOfWorkService.this);
+                }
+            }
+        }, 30_000);
     }
 
     public void doProofOfWork(ObjectMessage object) {
@@ -79,7 +88,6 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
                 messageRepo.save(plaintext);
             }
             ctx.getInventory().storeObject(object);
-            powRepo.removeObject(initialHash);
             ctx.getNetworkHandler().offer(object.getInventoryVector());
         } else {
             item.message.getAckMessage().setNonce(nonce);
@@ -96,6 +104,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
             }
             doProofOfWork(item.message.getTo(), object);
         }
+        powRepo.removeObject(initialHash);
     }
 
     @Override
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index a2b66f7..b90bf14 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -16,6 +16,7 @@
 
 package ch.dissem.bitmessage.entity;
 
+import ch.dissem.bitmessage.entity.payload.Msg;
 import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.entity.valueobject.Label;
@@ -511,7 +512,7 @@ public class Plaintext implements Streamable {
                 to = new BitmessageAddress(0, 0, destinationRipe);
             }
             if (type == Type.MSG && ackMessage == null && ackData == null) {
-                ackData = cryptography().randomBytes(32);
+                ackData = cryptography().randomBytes(Msg.ACK_LENGTH);
             }
             return new Plaintext(this);
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java
index 4ae4696..176d938 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/GenericPayload.java
@@ -53,6 +53,10 @@ public class GenericPayload extends ObjectPayload {
         return stream;
     }
 
+    public byte[] getData() {
+        return data;
+    }
+
     @Override
     public void write(OutputStream stream) throws IOException {
         stream.write(data);
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java
index edc4643..64a010c 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/Msg.java
@@ -33,6 +33,7 @@ import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
  */
 public class Msg extends ObjectPayload implements Encrypted, PlaintextHolder {
     private static final long serialVersionUID = 4327495048296365733L;
+    public static final int ACK_LENGTH = 32;
 
     private long stream;
     private CryptoBox encrypted;
diff --git a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
index 49db9d6..53e1676 100644
--- a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
+++ b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
@@ -23,6 +23,8 @@ import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.entity.payload.*;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
 import ch.dissem.bitmessage.exception.NodeException;
+import ch.dissem.bitmessage.utils.TTL;
+import ch.dissem.bitmessage.utils.UnixTime;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -210,6 +212,6 @@ public class Factory {
         if (plaintext == null || plaintext.getAckData() == null)
             return null;
         GenericPayload ack = new GenericPayload(3, plaintext.getFrom().getStream(), plaintext.getAckData());
-        return new ObjectMessage.Builder().objectType(MSG).payload(ack).build();
+        return new ObjectMessage.Builder().objectType(MSG).payload(ack).expiresTime(UnixTime.now(+TTL.msg())).build();
     }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
index c4cff5c..0c46499 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
@@ -34,6 +34,8 @@ public interface MessageRepository {
 
     Plaintext getMessage(byte[] initialHash);
 
+    Plaintext getMessageForAck(byte[] ackData);
+
     List<Plaintext> findMessages(Label label);
 
     List<Plaintext> findMessages(Status status);
diff --git a/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java b/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
index 6751819..03cbf5e 100644
--- a/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
+++ b/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
@@ -5,11 +5,13 @@ import ch.dissem.bitmessage.entity.BitmessageAddress;
 import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.networking.DefaultNetworkHandler;
 import ch.dissem.bitmessage.ports.DefaultLabeler;
+import ch.dissem.bitmessage.ports.Labeler;
 import ch.dissem.bitmessage.repository.*;
 import ch.dissem.bitmessage.utils.TTL;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import org.mockito.Mockito;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -20,6 +22,7 @@ import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.DOES_ACK;
 import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertThat;
+import static org.mockito.Matchers.any;
 
 /**
  * @author Christian Basler
@@ -29,6 +32,7 @@ public class SystemTest {
 
     private BitmessageContext alice;
     private TestListener aliceListener = new TestListener();
+    private Labeler aliceLabeler = Mockito.spy(new DebugLabeler("Alice"));
     private BitmessageAddress aliceIdentity;
 
     private BitmessageContext bob;
@@ -53,7 +57,7 @@ public class SystemTest {
                 .networkHandler(new DefaultNetworkHandler())
                 .cryptography(new BouncyCryptography())
                 .listener(aliceListener)
-                .labeler(new DebugLabeler("Alice"))
+                .labeler(aliceLabeler)
                 .build();
         alice.startup();
         aliceIdentity = alice.createIdentity(false, DOES_ACK);
@@ -93,6 +97,9 @@ public class SystemTest {
 
         assertThat(plaintext.getType(), equalTo(Plaintext.Type.MSG));
         assertThat(plaintext.getText(), equalTo(originalMessage));
+
+        Mockito.verify(aliceLabeler, Mockito.timeout(TimeUnit.MINUTES.toMillis(15)).atLeastOnce())
+                .markAsAcknowledged(any());
     }
 
     @Test
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java
index 1df12f6..beb4c80 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java
@@ -18,6 +18,7 @@ package ch.dissem.bitmessage.repository;
 
 import ch.dissem.bitmessage.entity.Streamable;
 import ch.dissem.bitmessage.entity.payload.ObjectType;
+import ch.dissem.bitmessage.exception.ApplicationException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -25,6 +26,7 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
+import java.util.Collection;
 
 import static ch.dissem.bitmessage.utils.Strings.hex;
 
@@ -85,4 +87,12 @@ public abstract class JdbcHelper {
             ps.setBytes(parameterIndex, os.toByteArray());
         }
     }
+
+    protected <T> T single(Collection<T> collection) {
+        if (collection.size() > 1) {
+            throw new ApplicationException("This shouldn't happen, found " + collection.size() +
+                    " messages, one or none was expected");
+        }
+        return collection.stream().findAny().orElse(null);
+    }
 }
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
index ae1b496..ffc639f 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
@@ -137,16 +137,12 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
 
     @Override
     public Plaintext getMessage(byte[] initialHash) {
-        List<Plaintext> plaintexts = find("initial_hash=X'" + Strings.hex(initialHash) + "'");
-        switch (plaintexts.size()) {
-            case 0:
-                return null;
-            case 1:
-                return plaintexts.get(0);
-            default:
-                throw new ApplicationException("This shouldn't happen, found " + plaintexts.size() +
-                        " messages, one or none was expected");
-        }
+        return single(find("initial_hash=X'" + Strings.hex(initialHash) + "'"));
+    }
+
+    @Override
+    public Plaintext getMessageForAck(byte[] ackData) {
+        return single(find("ack_data=X'" + Strings.hex(ackData) + "' AND status='" + Plaintext.Status.SENT + "'"));
     }
 
     @Override
@@ -174,7 +170,7 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
         try (
                 Connection connection = config.getConnection();
                 Statement stmt = connection.createStatement();
-                ResultSet rs = stmt.executeQuery("SELECT id, iv, type, sender, recipient, data, sent, received, status " +
+                ResultSet rs = stmt.executeQuery("SELECT id, iv, type, sender, recipient, data, ack_data, sent, received, status " +
                         "FROM Message WHERE " + where)
         ) {
             while (rs.next()) {
@@ -187,6 +183,7 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
                 builder.IV(new InventoryVector(iv));
                 builder.from(ctx.getAddressRepository().getAddress(rs.getString("sender")));
                 builder.to(ctx.getAddressRepository().getAddress(rs.getString("recipient")));
+                builder.ackData(rs.getBytes("ack_data"));
                 builder.sent(rs.getLong("sent"));
                 builder.received(rs.getLong("received"));
                 builder.status(Plaintext.Status.valueOf(rs.getString("status")));
@@ -268,8 +265,8 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
 
     private void insert(Connection connection, Plaintext message) throws SQLException, IOException {
         try (PreparedStatement ps = connection.prepareStatement(
-                "INSERT INTO Message (iv, type, sender, recipient, data, sent, received, status, initial_hash) " +
-                        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)",
+                "INSERT INTO Message (iv, type, sender, recipient, data, ack_data, sent, received, status, initial_hash) " +
+                        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
                 Statement.RETURN_GENERATED_KEYS)
         ) {
             ps.setBytes(1, message.getInventoryVector() == null ? null : message.getInventoryVector().getHash());
@@ -277,10 +274,11 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
             ps.setString(3, message.getFrom().getAddress());
             ps.setString(4, message.getTo() == null ? null : message.getTo().getAddress());
             writeBlob(ps, 5, message);
-            ps.setLong(6, message.getSent());
-            ps.setLong(7, message.getReceived());
-            ps.setString(8, message.getStatus() == null ? null : message.getStatus().name());
-            ps.setBytes(9, message.getInitialHash());
+            ps.setBytes(6, message.getAckData());
+            ps.setLong(7, message.getSent());
+            ps.setLong(8, message.getReceived());
+            ps.setString(9, message.getStatus() == null ? null : message.getStatus().name());
+            ps.setBytes(10, message.getInitialHash());
 
             ps.executeUpdate();
             // get generated id
diff --git a/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql b/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
new file mode 100644
index 0000000..8b43b0a
--- /dev/null
+++ b/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
@@ -0,0 +1 @@
+ALTER TABLE Message ADD COLUMN ack_data BINARY(32);

From a67ac27921fa89545109d61e42e42a27af7ea62b Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Tue, 10 May 2016 07:26:25 +0200
Subject: [PATCH 12/20] Fixed yet another test

---
 .../src/main/java/ch/dissem/bitmessage/BitmessageContext.java | 2 +-
 .../main/java/ch/dissem/bitmessage/ProofOfWorkService.java    | 4 ++--
 .../java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java     | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index 2307958..aef6a67 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -69,7 +69,7 @@ public class BitmessageContext {
     private BitmessageContext(Builder builder) {
         ctx = new InternalContext(builder);
         labeler = builder.labeler;
-        ctx.getProofOfWorkService().doMissingProofOfWork();
+        ctx.getProofOfWorkService().doMissingProofOfWork(30_000); // TODO: this should be configurable
 
         networkListener = new DefaultMessageListener(ctx, labeler, builder.listener);
         sendPubkeyOnIdentityCreation = builder.sendPubkeyOnIdentityCreation;
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
index d242b79..04016b5 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
@@ -30,7 +30,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
     private ProofOfWorkRepository powRepo;
     private MessageRepository messageRepo;
 
-    public void doMissingProofOfWork() {
+    public void doMissingProofOfWork(long delayInMilliseconds) {
         final List<byte[]> items = powRepo.getItems();
         if (items.isEmpty()) return;
 
@@ -45,7 +45,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
                             ProofOfWorkService.this);
                 }
             }
-        }, 30_000);
+        }, delayInMilliseconds);
     }
 
     public void doProofOfWork(ObjectMessage object) {
diff --git a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
index fa58cfe..c4529e3 100644
--- a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
@@ -77,9 +77,9 @@ public class ProofOfWorkServiceTest {
         when(proofOfWorkRepo.getItem(any(byte[].class))).thenReturn(new ProofOfWorkRepository.Item(null, 1001, 1002));
         doNothing().when(cryptography).doProofOfWork(any(ObjectMessage.class), anyLong(), anyLong(), any(ProofOfWorkEngine.Callback.class));
 
-        proofOfWorkService.doMissingProofOfWork();
+        proofOfWorkService.doMissingProofOfWork(10);
 
-        verify(cryptography).doProofOfWork((ObjectMessage) isNull(), eq(1001L), eq(1002L),
+        verify(cryptography, timeout(1000)).doProofOfWork((ObjectMessage) isNull(), eq(1001L), eq(1002L),
                 any(ProofOfWorkEngine.Callback.class));
     }
 

From e44dd967d0230f3509b8c8ee0e65e210bc6b2246 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 13 May 2016 12:24:16 +0200
Subject: [PATCH 13/20] Test for NodeRegistry

---
 core/build.gradle                             |  1 +
 .../bitmessage/ports/MemoryNodeRegistry.java  | 14 +--
 .../bitmessage/ports/NodeRegistryTest.java    | 95 +++++++++++++++++++
 3 files changed, 101 insertions(+), 9 deletions(-)
 create mode 100644 core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java

diff --git a/core/build.gradle b/core/build.gradle
index 8754cb3..dd100e6 100644
--- a/core/build.gradle
+++ b/core/build.gradle
@@ -26,6 +26,7 @@ artifacts {
 dependencies {
     compile 'org.slf4j:slf4j-api:1.7.12'
     testCompile 'junit:junit:4.11'
+    testCompile 'org.hamcrest:hamcrest-library:1.3'
     testCompile 'org.mockito:mockito-core:1.10.19'
     testCompile project(':cryptography-bc')
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/MemoryNodeRegistry.java b/core/src/main/java/ch/dissem/bitmessage/ports/MemoryNodeRegistry.java
index c68a474..ff2ad95 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/MemoryNodeRegistry.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/MemoryNodeRegistry.java
@@ -46,15 +46,11 @@ public class MemoryNodeRegistry implements NodeRegistry {
             while (scanner.hasNext()) {
                 try {
                     String line = scanner.nextLine().trim();
-                    if (line.startsWith("#") || line.isEmpty()) {
-                        // Ignore
-                        continue;
-                    }
                     if (line.startsWith("[stream")) {
                         stream = Long.parseLong(line.substring(8, line.lastIndexOf(']')));
                         streamSet = new HashSet<>();
                         stableNodes.put(stream, streamSet);
-                    } else if (streamSet != null) {
+                    } else if (streamSet != null && !line.isEmpty() && !line.startsWith("#")) {
                         int portIndex = line.lastIndexOf(':');
                         InetAddress[] inetAddresses = InetAddress.getAllByName(line.substring(0, portIndex));
                         int port = Integer.valueOf(line.substring(portIndex + 1));
@@ -89,12 +85,12 @@ public class MemoryNodeRegistry implements NodeRegistry {
                         known.remove(node);
                     }
                 }
-            } else {
-                Set<NetworkAddress> nodes = stableNodes.get(stream);
-                if (nodes == null || nodes.isEmpty()) {
+            }
+            if (result.isEmpty()) {
+                if (stableNodes.isEmpty()) {
                     loadStableNodes();
-                    nodes = stableNodes.get(stream);
                 }
+                Set<NetworkAddress> nodes = stableNodes.get(stream);
                 if (nodes != null && !nodes.isEmpty()) {
                     // To reduce load on stable nodes, only return one
                     result.add(selectRandom(nodes));
diff --git a/core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java b/core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java
new file mode 100644
index 0000000..0e54446
--- /dev/null
+++ b/core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2016 Christian Basler
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package ch.dissem.bitmessage.ports;
+
+import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
+import ch.dissem.bitmessage.utils.UnixTime;
+import org.junit.Test;
+
+import java.util.Arrays;
+
+import static ch.dissem.bitmessage.utils.UnixTime.HOUR;
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.assertThat;
+
+public class NodeRegistryTest {
+    private NodeRegistry registry = new MemoryNodeRegistry();
+
+    @Test
+    public void ensureGetKnownNodesWithoutStreamsYieldsEmpty() {
+        assertThat(registry.getKnownAddresses(10), empty());
+    }
+
+    @Test
+    public void ensureGetKnownNodesForStream1YieldsResult() {
+        assertThat(registry.getKnownAddresses(10, 1), hasSize(1));
+    }
+
+    @Test
+    public void ensureNodeIsStored() {
+        registry.offerAddresses(Arrays.asList(
+                new NetworkAddress.Builder()
+                        .ipv4(127, 0, 0, 1)
+                        .port(42)
+                        .stream(1)
+                        .time(UnixTime.now())
+                        .build(),
+                new NetworkAddress.Builder()
+                        .ipv4(127, 0, 0, 2)
+                        .port(42)
+                        .stream(1)
+                        .time(UnixTime.now())
+                        .build(),
+                new NetworkAddress.Builder()
+                        .ipv4(127, 0, 0, 2)
+                        .port(42)
+                        .stream(2)
+                        .time(UnixTime.now())
+                        .build()
+        ));
+        assertThat(registry.getKnownAddresses(10, 1).size(), is(2));
+        assertThat(registry.getKnownAddresses(10, 2).size(), is(1));
+        assertThat(registry.getKnownAddresses(10, 1, 2).size(), is(3));
+    }
+
+    @Test
+    public void ensureOldNodesAreRemoved() {
+        registry.offerAddresses(Arrays.asList(
+                new NetworkAddress.Builder()
+                        .ipv4(127, 0, 0, 1)
+                        .port(42)
+                        .stream(1)
+                        .time(UnixTime.now())
+                        .build(),
+                new NetworkAddress.Builder()
+                        .ipv4(127, 0, 0, 2)
+                        .port(42)
+                        .stream(1)
+                        .time(UnixTime.now(-4 * HOUR))
+                        .build(),
+                new NetworkAddress.Builder()
+                        .ipv4(127, 0, 0, 2)
+                        .port(42)
+                        .stream(2)
+                        .time(UnixTime.now())
+                        .build()
+        ));
+        assertThat(registry.getKnownAddresses(10, 1).size(), is(1));
+        assertThat(registry.getKnownAddresses(10, 2).size(), is(1));
+        assertThat(registry.getKnownAddresses(10, 1, 2).size(), is(2));
+    }
+}

From 43f42dd400a2af4ca6b15f8065c8bdc57b7c3ca9 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 20 May 2016 07:32:41 +0200
Subject: [PATCH 14/20] This breaks a lot of things, but it seems necessary.
 Implemented the resending mechanism and fixed many problems on the way, but
 tests and triggers are still to do.

---
 .../dissem/bitmessage/BitmessageContext.java  |  4 +-
 .../bitmessage/DefaultMessageListener.java    |  9 ++-
 .../ch/dissem/bitmessage/InternalContext.java | 16 +++-
 .../dissem/bitmessage/ProofOfWorkService.java |  2 +
 .../dissem/bitmessage/entity/Plaintext.java   | 74 ++++++++++++++++---
 .../ch/dissem/bitmessage/entity/Version.java  |  4 +-
 .../ch/dissem/bitmessage/factory/Factory.java |  2 +-
 .../bitmessage/ports/MessageRepository.java   |  2 +
 .../bitmessage/entity/SerializationTest.java  | 28 ++++++-
 .../bitmessage/ports/NodeRegistryTest.java    |  4 +
 .../bitmessage/networking/Connection.java     | 19 +++--
 .../networking/ConnectionOrganizer.java       |  7 +-
 .../networking/DefaultNetworkHandler.java     |  5 +-
 .../bitmessage/networking/ServerRunnable.java |  7 +-
 .../repository/JdbcMessageRepository.java     | 50 ++++++++++---
 .../migration/V3.2__Update_table_message.sql  |  3 +
 .../repository/JdbcMessageRepositoryTest.java | 18 ++++-
 17 files changed, 202 insertions(+), 52 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index aef6a67..ad21e72 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -167,13 +167,13 @@ public class BitmessageContext {
             LOG.info("Sending message.");
             ctx.getMessageRepository().save(msg);
             if (msg.getType() == MSG) {
-                ctx.send(msg, TTL.msg());
+                ctx.send(msg);
             } else {
                 ctx.send(
                         msg.getFrom(),
                         to,
                         Factory.getBroadcast(msg),
-                        TTL.msg()
+                        msg.getTTL()
                 );
             }
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
index 05961e4..b5d70d1 100644
--- a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
+++ b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.java
@@ -51,8 +51,11 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
     @SuppressWarnings("ConstantConditions")
     public void receive(ObjectMessage object) throws IOException {
         ObjectPayload payload = object.getPayload();
-        if (payload.getType() == null && payload instanceof GenericPayload) {
-            receive((GenericPayload) payload);
+        if (payload.getType() == null) {
+            if (payload instanceof GenericPayload) {
+                receive((GenericPayload) payload);
+            }
+            return;
         }
 
         switch (payload.getType()) {
@@ -115,7 +118,7 @@ class DefaultMessageListener implements NetworkHandler.MessageListener {
         for (Plaintext msg : messages) {
             ctx.getLabeler().markAsSending(msg);
             ctx.getMessageRepository().save(msg);
-            ctx.send(msg, TTL.msg());
+            ctx.send(msg);
         }
     }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
index 884dd16..057bfef 100644
--- a/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/InternalContext.java
@@ -28,6 +28,7 @@ import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.List;
 import java.util.TreeSet;
 
 /**
@@ -160,12 +161,13 @@ public class InternalContext {
         return port;
     }
 
-    public void send(final Plaintext plaintext, final long timeToLive) {
+    public void send(final Plaintext plaintext) {
         if (plaintext.getAckMessage() != null) {
-            long expires = UnixTime.now(+timeToLive);
+            long expires = UnixTime.now(+plaintext.getTTL());
+            LOG.info("Expires at " + expires);
             proofOfWorkService.doProofOfWorkWithAck(plaintext, expires);
         } else {
-            send(plaintext.getFrom(), plaintext.getTo(), new Msg(plaintext), timeToLive);
+            send(plaintext.getFrom(), plaintext.getTo(), new Msg(plaintext), plaintext.getTTL());
         }
     }
 
@@ -278,6 +280,14 @@ public class InternalContext {
         }
     }
 
+    public void resendUnacknowledged() {
+        List<Plaintext> messages = messageRepository.findMessagesToResend();
+        for (Plaintext message : messages) {
+            send(message);
+            messageRepository.save(message);
+        }
+    }
+
     public long getClientNonce() {
         return clientNonce;
     }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
index 04016b5..e9a27db 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
@@ -69,6 +69,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
 
     public void doProofOfWorkWithAck(Plaintext plaintext, long expirationTime) {
         final ObjectMessage ack = plaintext.getAckMessage();
+        messageRepo.save(plaintext);
         Item item = new Item(ack, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES,
                 expirationTime, plaintext);
         powRepo.putObject(item);
@@ -84,6 +85,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
             Plaintext plaintext = messageRepo.getMessage(initialHash);
             if (plaintext != null) {
                 plaintext.setInventoryVector(object.getInventoryVector());
+                plaintext.updateNextTry();
                 ctx.getLabeler().markAsSent(plaintext);
                 messageRepo.save(plaintext);
             }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index b90bf14..90c3c50 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -17,13 +17,14 @@
 package ch.dissem.bitmessage.entity;
 
 import ch.dissem.bitmessage.entity.payload.Msg;
-import ch.dissem.bitmessage.entity.payload.Pubkey;
+import ch.dissem.bitmessage.entity.payload.Pubkey.Feature;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.factory.Factory;
 import ch.dissem.bitmessage.utils.Decode;
 import ch.dissem.bitmessage.utils.Encode;
+import ch.dissem.bitmessage.utils.TTL;
 import ch.dissem.bitmessage.utils.UnixTime;
 
 import java.io.*;
@@ -54,6 +55,10 @@ public class Plaintext implements Streamable {
     private Set<Label> labels;
     private byte[] initialHash;
 
+    private long ttl;
+    private int retries;
+    private Long nextTry;
+
     private Plaintext(Builder builder) {
         id = builder.id;
         inventoryVector = builder.inventoryVector;
@@ -74,6 +79,9 @@ public class Plaintext implements Streamable {
         sent = builder.sent;
         received = builder.received;
         labels = builder.labels;
+        ttl = builder.ttl;
+        retries = builder.retries;
+        nextTry = builder.nextTry;
     }
 
     public static Plaintext read(Type type, InputStream in) throws IOException {
@@ -96,7 +104,7 @@ public class Plaintext implements Streamable {
                 .destinationRipe(type == Type.MSG ? Decode.bytes(in, 20) : null)
                 .encoding(Decode.varInt(in))
                 .message(Decode.varBytes(in))
-                .ack(type == Type.MSG ? Decode.varBytes(in) : null);
+                .ackMessage(type == Type.MSG ? Decode.varBytes(in) : null);
     }
 
     public InventoryVector getInventoryVector() {
@@ -174,12 +182,10 @@ public class Plaintext implements Streamable {
         Encode.varInt(message.length, out);
         out.write(message);
         if (type == Type.MSG) {
-            if (to.has(Pubkey.Feature.DOES_ACK) && getAckMessage() != null) {
+            if (to.has(Feature.DOES_ACK) && getAckMessage() != null) {
                 ByteArrayOutputStream ack = new ByteArrayOutputStream();
                 getAckMessage().write(ack);
-                byte[] data = ack.toByteArray();
-                Encode.varInt(data.length, out);
-                out.write(data);
+                Encode.varBytes(ack.toByteArray(), out);
             } else {
                 Encode.varInt(0, out);
             }
@@ -224,6 +230,30 @@ public class Plaintext implements Streamable {
         this.status = status;
     }
 
+    public long getTTL() {
+        return ttl;
+    }
+
+    public int getRetries() {
+        return retries;
+    }
+
+    public Long getNextTry() {
+        return nextTry;
+    }
+
+    public void updateNextTry() {
+        if (nextTry == null) {
+            if (sent != null && to.has(Feature.DOES_ACK)) {
+                nextTry = sent + ttl;
+                retries++;
+            }
+        } else {
+            nextTry = nextTry + (1 << retries) * ttl;
+            retries++;
+        }
+    }
+
     public String getSubject() {
         Scanner s = new Scanner(new ByteArrayInputStream(message), "UTF-8");
         String firstLine = s.nextLine();
@@ -272,9 +302,7 @@ public class Plaintext implements Streamable {
 
     public void addLabels(Label... labels) {
         if (labels != null) {
-            for (Label label : labels) {
-                this.labels.add(label);
-            }
+            Collections.addAll(this.labels, labels);
         }
     }
 
@@ -366,6 +394,9 @@ public class Plaintext implements Streamable {
         private long received;
         private Status status;
         private Set<Label> labels = new HashSet<>();
+        private long ttl;
+        private int retries;
+        private Long nextTry;
 
         public Builder(Type type) {
             this.type = type;
@@ -459,14 +490,15 @@ public class Plaintext implements Streamable {
             return this;
         }
 
-        public Builder ack(byte[] ack) {
-            if (type != Type.MSG && ack != null) throw new IllegalArgumentException("ack only allowed for msg");
+        public Builder ackMessage(byte[] ack) {
+            if (type != Type.MSG && ack != null) throw new IllegalArgumentException("ackMessage only allowed for msg");
             this.ackMessage = ack;
             return this;
         }
 
         public Builder ackData(byte[] ackData) {
-            if (type != Type.MSG && ackData != null) throw new IllegalArgumentException("ack only allowed for msg");
+            if (type != Type.MSG && ackData != null)
+                throw new IllegalArgumentException("ackMessage only allowed for msg");
             this.ackData = ackData;
             return this;
         }
@@ -496,6 +528,21 @@ public class Plaintext implements Streamable {
             return this;
         }
 
+        public Builder ttl(long ttl) {
+            this.ttl = ttl;
+            return this;
+        }
+
+        public Builder retries(int retries) {
+            this.retries = retries;
+            return this;
+        }
+
+        public Builder nextTry(Long nextTry) {
+            this.nextTry = nextTry;
+            return this;
+        }
+
         public Plaintext build() {
             if (from == null) {
                 from = new BitmessageAddress(Factory.createPubkey(
@@ -514,6 +561,9 @@ public class Plaintext implements Streamable {
             if (type == Type.MSG && ackMessage == null && ackData == null) {
                 ackData = cryptography().randomBytes(Msg.ACK_LENGTH);
             }
+            if (ttl <= 0) {
+                ttl = TTL.msg();
+            }
             return new Plaintext(this);
         }
     }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Version.java b/core/src/main/java/ch/dissem/bitmessage/entity/Version.java
index 3722528..8539be1 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Version.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Version.java
@@ -145,13 +145,13 @@ public class Version implements MessagePayload {
         private String userAgent;
         private long[] streamNumbers;
 
-        public Builder defaults() {
+        public Builder defaults(long clientNonce) {
             version = BitmessageContext.CURRENT_VERSION;
             services = 1;
             timestamp = UnixTime.now();
-            nonce = new Random().nextInt();
             userAgent = "/Jabit:0.0.1/";
             streamNumbers = new long[]{1};
+            nonce = clientNonce;
             return this;
         }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
index 53e1676..0597f6a 100644
--- a/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
+++ b/core/src/main/java/ch/dissem/bitmessage/factory/Factory.java
@@ -212,6 +212,6 @@ public class Factory {
         if (plaintext == null || plaintext.getAckData() == null)
             return null;
         GenericPayload ack = new GenericPayload(3, plaintext.getFrom().getStream(), plaintext.getAckData());
-        return new ObjectMessage.Builder().objectType(MSG).payload(ack).expiresTime(UnixTime.now(+TTL.msg())).build();
+        return new ObjectMessage.Builder().objectType(MSG).payload(ack).expiresTime(UnixTime.now(plaintext.getTTL())).build();
     }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
index 0c46499..aca16b9 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.java
@@ -44,6 +44,8 @@ public interface MessageRepository {
 
     List<Plaintext> findMessages(BitmessageAddress sender);
 
+    List<Plaintext> findMessagesToResend();
+
     void save(Plaintext message);
 
     void remove(Plaintext message);
diff --git a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
index 26d8a35..5405f23 100644
--- a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.java
@@ -82,7 +82,7 @@ public class SerializationTest extends TestBase {
                 .from(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"))
                 .to(TestUtils.loadContact())
                 .message("Subject", "Message")
-                .ackData("ack".getBytes())
+                .ackData("ackMessage".getBytes())
                 .signature(new byte[0])
                 .build();
         ByteArrayOutputStream out = new ByteArrayOutputStream();
@@ -98,6 +98,32 @@ public class SerializationTest extends TestBase {
         assertEquals(p1, p2);
     }
 
+    @Test
+    public void ensurePlaintextWithAckMessageIsSerializedAndDeserializedCorrectly() throws Exception {
+        Plaintext p1 = new Plaintext.Builder(MSG)
+                .from(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"))
+                .to(TestUtils.loadContact())
+                .message("Subject", "Message")
+                .ackData("ackMessage".getBytes())
+                .signature(new byte[0])
+                .build();
+        ObjectMessage ackMessage1 = p1.getAckMessage();
+        assertNotNull(ackMessage1);
+
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        p1.write(out);
+        ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
+        Plaintext p2 = Plaintext.read(MSG, in);
+
+        // Received is automatically set on deserialization, so we'll need to set it to 0
+        Field received = Plaintext.class.getDeclaredField("received");
+        received.setAccessible(true);
+        received.set(p2, 0L);
+
+        assertEquals(p1, p2);
+        assertEquals(ackMessage1, p2.getAckMessage());
+    }
+
     @Test
     public void ensureNetworkMessageIsSerializedAndDeserializedCorrectly() throws Exception {
         ArrayList<InventoryVector> ivs = new ArrayList<>(50000);
diff --git a/core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java b/core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java
index 0e54446..993e3a9 100644
--- a/core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/ports/NodeRegistryTest.java
@@ -34,6 +34,10 @@ public class NodeRegistryTest {
         assertThat(registry.getKnownAddresses(10), empty());
     }
 
+    /**
+     * Please note that this test fails if there is no internet connection,
+     * as the initial nodes' IP addresses are determined by DNS lookup.
+     */
     @Test
     public void ensureGetKnownNodesForStream1YieldsResult() {
         assertThat(registry.getKnownAddresses(10, 1), hasSize(1));
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java b/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
index 4717675..9ed19bc 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
@@ -72,6 +72,7 @@ class Connection {
     private final ReaderRunnable reader = new ReaderRunnable();
     private final WriterRunnable writer = new WriterRunnable();
     private final DefaultNetworkHandler networkHandler;
+    private final long clientNonce;
 
     private volatile State state;
     private InputStream in;
@@ -83,22 +84,23 @@ class Connection {
     private long lastObjectTime;
 
     public Connection(InternalContext context, Mode mode, Socket socket, MessageListener listener,
-                      Set<InventoryVector> requestedObjectsMap) throws IOException {
+                      Set<InventoryVector> requestedObjectsMap, long clientNonce) throws IOException {
         this(context, mode, listener, socket, requestedObjectsMap,
                 Collections.newSetFromMap(new ConcurrentHashMap<InventoryVector, Boolean>(10_000)),
                 new NetworkAddress.Builder().ip(socket.getInetAddress()).port(socket.getPort()).stream(1).build(),
-                0);
+                0, clientNonce);
     }
 
     public Connection(InternalContext context, Mode mode, NetworkAddress node, MessageListener listener,
-                      Set<InventoryVector> requestedObjectsMap) {
+                      Set<InventoryVector> requestedObjectsMap, long clientNonce) {
         this(context, mode, listener, new Socket(), requestedObjectsMap,
                 Collections.newSetFromMap(new ConcurrentHashMap<InventoryVector, Boolean>(10_000)),
-                node, 0);
+                node, 0, clientNonce);
     }
 
     private Connection(InternalContext context, Mode mode, MessageListener listener, Socket socket,
-                       Set<InventoryVector> commonRequestedObjects, Set<InventoryVector> requestedObjects, NetworkAddress node, long syncTimeout) {
+                       Set<InventoryVector> commonRequestedObjects, Set<InventoryVector> requestedObjects,
+                       NetworkAddress node, long syncTimeout, long clientNonce) {
         this.startTime = UnixTime.now();
         this.ctx = context;
         this.mode = mode;
@@ -112,6 +114,7 @@ class Connection {
         this.syncTimeout = (syncTimeout > 0 ? UnixTime.now(+syncTimeout) : 0);
         this.ivCache = new ConcurrentHashMap<>();
         this.networkHandler = (DefaultNetworkHandler) ctx.getNetworkHandler();
+        this.clientNonce = clientNonce;
     }
 
     public static Connection sync(InternalContext ctx, InetAddress address, int port, MessageListener listener,
@@ -120,7 +123,7 @@ class Connection {
                 new HashSet<InventoryVector>(),
                 new HashSet<InventoryVector>(),
                 new NetworkAddress.Builder().ip(address).port(port).stream(1).build(),
-                timeoutInSeconds);
+                timeoutInSeconds, cryptography().randomNonce());
     }
 
     public long getStartTime() {
@@ -362,7 +365,7 @@ class Connection {
             try (Socket socket = Connection.this.socket) {
                 initSocket(socket);
                 if (mode == CLIENT || mode == SYNC) {
-                    send(new Version.Builder().defaults().addrFrom(host).addrRecv(node).build());
+                    send(new Version.Builder().defaults(clientNonce).addrFrom(host).addrRecv(node).build());
                 }
                 while (state != DISCONNECTED) {
                     if (mode != SYNC) {
@@ -446,7 +449,7 @@ class Connection {
                 send(new VerAck());
                 switch (mode) {
                     case SERVER:
-                        send(new Version.Builder().defaults().addrFrom(host).addrRecv(node).build());
+                        send(new Version.Builder().defaults(clientNonce).addrFrom(host).addrRecv(node).build());
                         break;
                     case CLIENT:
                     case SYNC:
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/ConnectionOrganizer.java b/networking/src/main/java/ch/dissem/bitmessage/networking/ConnectionOrganizer.java
index 1163d1c..c25a31c 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/ConnectionOrganizer.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/ConnectionOrganizer.java
@@ -38,15 +38,17 @@ public class ConnectionOrganizer implements Runnable {
     private final InternalContext ctx;
     private final DefaultNetworkHandler networkHandler;
     private final NetworkHandler.MessageListener listener;
+    private final long clientNonce;
 
     private Connection initialConnection;
 
     public ConnectionOrganizer(InternalContext ctx,
                                DefaultNetworkHandler networkHandler,
-                               NetworkHandler.MessageListener listener) {
+                               NetworkHandler.MessageListener listener, long clientNonce) {
         this.ctx = ctx;
         this.networkHandler = networkHandler;
         this.listener = listener;
+        this.clientNonce = clientNonce;
     }
 
     @Override
@@ -91,7 +93,8 @@ public class ConnectionOrganizer implements Runnable {
                                 NETWORK_MAGIC_NUMBER - active, ctx.getStreams());
                         boolean first = active == 0 && initialConnection == null;
                         for (NetworkAddress address : addresses) {
-                            Connection c = new Connection(ctx, CLIENT, address, listener, networkHandler.requestedObjects);
+                            Connection c = new Connection(ctx, CLIENT, address, listener,
+                                    networkHandler.requestedObjects, clientNonce);
                             if (first) {
                                 initialConnection = c;
                                 first = false;
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java b/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
index 289aa79..635aed2 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
@@ -28,7 +28,6 @@ import ch.dissem.bitmessage.factory.Factory;
 import ch.dissem.bitmessage.ports.NetworkHandler;
 import ch.dissem.bitmessage.utils.Collections;
 import ch.dissem.bitmessage.utils.Property;
-import ch.dissem.bitmessage.utils.ThreadFactoryBuilder;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -109,9 +108,9 @@ public class DefaultNetworkHandler implements NetworkHandler, ContextHolder {
         try {
             running = true;
             connections.clear();
-            server = new ServerRunnable(ctx, this, listener);
+            server = new ServerRunnable(ctx, this, listener, ctx.getClientNonce());
             pool.execute(server);
-            pool.execute(new ConnectionOrganizer(ctx, this, listener));
+            pool.execute(new ConnectionOrganizer(ctx, this, listener, ctx.getClientNonce()));
         } catch (IOException e) {
             throw new ApplicationException(e);
         }
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/ServerRunnable.java b/networking/src/main/java/ch/dissem/bitmessage/networking/ServerRunnable.java
index bf6d6f6..5a866b9 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/ServerRunnable.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/ServerRunnable.java
@@ -37,12 +37,15 @@ public class ServerRunnable implements Runnable, Closeable {
     private final ServerSocket serverSocket;
     private final DefaultNetworkHandler networkHandler;
     private final NetworkHandler.MessageListener listener;
+    private final long clientNonce;
 
-    public ServerRunnable(InternalContext ctx, DefaultNetworkHandler networkHandler, NetworkHandler.MessageListener listener) throws IOException {
+    public ServerRunnable(InternalContext ctx, DefaultNetworkHandler networkHandler,
+                          NetworkHandler.MessageListener listener, long clientNonce) throws IOException {
         this.ctx = ctx;
         this.networkHandler = networkHandler;
         this.listener = listener;
         this.serverSocket = new ServerSocket(ctx.getPort());
+        this.clientNonce = clientNonce;
     }
 
     @Override
@@ -52,7 +55,7 @@ public class ServerRunnable implements Runnable, Closeable {
                 Socket socket = serverSocket.accept();
                 socket.setSoTimeout(Connection.READ_TIMEOUT);
                 networkHandler.startConnection(new Connection(ctx, SERVER, socket, listener,
-                        networkHandler.requestedObjects));
+                        networkHandler.requestedObjects, clientNonce));
             } catch (IOException e) {
                 LOG.debug(e.getMessage(), e);
             }
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
index ffc639f..7ac42f9 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
@@ -24,6 +24,8 @@ import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.ports.MessageRepository;
 import ch.dissem.bitmessage.utils.Strings;
+import ch.dissem.bitmessage.utils.TTL;
+import ch.dissem.bitmessage.utils.UnixTime;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -165,13 +167,20 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
         return find("sender='" + sender.getAddress() + "'");
     }
 
+    @Override
+    public List<Plaintext> findMessagesToResend() {
+        return find("status='" + Plaintext.Status.SENT.name() + "'" +
+                " AND next_try < " + UnixTime.now());
+    }
+
     private List<Plaintext> find(String where) {
         List<Plaintext> result = new LinkedList<>();
         try (
                 Connection connection = config.getConnection();
                 Statement stmt = connection.createStatement();
-                ResultSet rs = stmt.executeQuery("SELECT id, iv, type, sender, recipient, data, ack_data, sent, received, status " +
-                        "FROM Message WHERE " + where)
+                ResultSet rs = stmt.executeQuery(
+                        "SELECT id, iv, type, sender, recipient, data, ack_data, sent, received, initial_hash, status, ttl, retries, next_try " +
+                                "FROM Message WHERE " + where)
         ) {
             while (rs.next()) {
                 byte[] iv = rs.getBytes("iv");
@@ -187,8 +196,13 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
                 builder.sent(rs.getLong("sent"));
                 builder.received(rs.getLong("received"));
                 builder.status(Plaintext.Status.valueOf(rs.getString("status")));
+                builder.ttl(rs.getLong("ttl"));
+                builder.retries(rs.getInt("retries"));
+                builder.nextTry(rs.getLong("next_try"));
                 builder.labels(findLabels(connection, id));
-                result.add(builder.build());
+                Plaintext message = builder.build();
+                message.setInitialHash(rs.getBytes("initial_hash"));
+                result.add(message);
             }
         } catch (IOException | SQLException e) {
             LOG.error(e.getMessage(), e);
@@ -265,8 +279,9 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
 
     private void insert(Connection connection, Plaintext message) throws SQLException, IOException {
         try (PreparedStatement ps = connection.prepareStatement(
-                "INSERT INTO Message (iv, type, sender, recipient, data, ack_data, sent, received, status, initial_hash) " +
-                        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+                "INSERT INTO Message (iv, type, sender, recipient, data, ack_data, sent, received, " +
+                        "status, initial_hash, ttl, retries, next_try) " +
+                        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
                 Statement.RETURN_GENERATED_KEYS)
         ) {
             ps.setBytes(1, message.getInventoryVector() == null ? null : message.getInventoryVector().getHash());
@@ -279,6 +294,9 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
             ps.setLong(8, message.getReceived());
             ps.setString(9, message.getStatus() == null ? null : message.getStatus().name());
             ps.setBytes(10, message.getInitialHash());
+            ps.setLong(11, message.getTTL());
+            ps.setInt(12, message.getRetries());
+            ps.setObject(13, message.getNextTry());
 
             ps.executeUpdate();
             // get generated id
@@ -291,13 +309,23 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
 
     private void update(Connection connection, Plaintext message) throws SQLException, IOException {
         try (PreparedStatement ps = connection.prepareStatement(
-                "UPDATE Message SET iv=?, sent=?, received=?, status=?, initial_hash=? WHERE id=?")) {
+                "UPDATE Message SET iv=?, type=?, sender=?, recipient=?, data=?, ack_data=?, sent=?, received=?, " +
+                        "status=?, initial_hash=?, ttl=?, retries=?, next_try=? " +
+                        "WHERE id=?")) {
             ps.setBytes(1, message.getInventoryVector() == null ? null : message.getInventoryVector().getHash());
-            ps.setLong(2, message.getSent());
-            ps.setLong(3, message.getReceived());
-            ps.setString(4, message.getStatus() == null ? null : message.getStatus().name());
-            ps.setBytes(5, message.getInitialHash());
-            ps.setLong(6, (Long) message.getId());
+            ps.setString(2, message.getType().name());
+            ps.setString(3, message.getFrom().getAddress());
+            ps.setString(4, message.getTo() == null ? null : message.getTo().getAddress());
+            writeBlob(ps, 5, message);
+            ps.setBytes(6, message.getAckData());
+            ps.setLong(7, message.getSent());
+            ps.setLong(8, message.getReceived());
+            ps.setString(9, message.getStatus() == null ? null : message.getStatus().name());
+            ps.setBytes(10, message.getInitialHash());
+            ps.setLong(11, message.getTTL());
+            ps.setInt(12, message.getRetries());
+            ps.setObject(13, message.getNextTry());
+            ps.setLong(14, (Long) message.getId());
             ps.executeUpdate();
         }
     }
diff --git a/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql b/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
index 8b43b0a..38847cf 100644
--- a/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
+++ b/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
@@ -1 +1,4 @@
 ALTER TABLE Message ADD COLUMN ack_data BINARY(32);
+ALTER TABLE Message ADD COLUMN ttl      BIGINT NOT NULL;
+ALTER TABLE Message ADD COLUMN retries  INT NOT NULL DEFAULT 0;
+ALTER TABLE Message ADD COLUMN next_try BIGINT;
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
index 81051de..df8a42e 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
@@ -19,6 +19,7 @@ package ch.dissem.bitmessage.repository;
 import ch.dissem.bitmessage.BitmessageContext;
 import ch.dissem.bitmessage.InternalContext;
 import ch.dissem.bitmessage.entity.BitmessageAddress;
+import ch.dissem.bitmessage.entity.ObjectMessage;
 import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.entity.valueobject.Label;
@@ -32,6 +33,7 @@ import java.util.Arrays;
 import java.util.List;
 
 import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
+import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.DOES_ACK;
 import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.*;
@@ -59,14 +61,14 @@ public class JdbcMessageRepositoryTest extends TestBase {
                 .messageRepo(repo)
         );
 
-        BitmessageAddress tmp = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000));
+        BitmessageAddress tmp = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000, DOES_ACK));
         contactA = new BitmessageAddress(tmp.getAddress());
         contactA.setPubkey(tmp.getPubkey());
         addressRepo.save(contactA);
         contactB = new BitmessageAddress("BM-2cTtkBnb4BUYDndTKun6D9PjtueP2h1bQj");
         addressRepo.save(contactB);
 
-        identity = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000));
+        identity = new BitmessageAddress(new PrivateKey(false, 1, 1000, 1000, DOES_ACK));
         addressRepo.save(identity);
 
         inbox = repo.getLabels(Label.Type.INBOX).get(0);
@@ -123,6 +125,18 @@ public class JdbcMessageRepositoryTest extends TestBase {
         assertThat(other, is(message));
     }
 
+    @Test
+    public void ensureAckMessageCanBeUpdatedAndRetrieved() {
+        byte[] initialHash = new byte[64];
+        Plaintext message = repo.findMessages(contactA).get(0);
+        message.setInitialHash(initialHash);
+        ObjectMessage ackMessage = message.getAckMessage();
+        repo.save(message);
+        Plaintext other = repo.getMessage(initialHash);
+        assertThat(other, is(message));
+        assertThat(other.getAckMessage(), is(ackMessage));
+    }
+
     @Test
     public void testFindMessagesByStatus() throws Exception {
         List<Plaintext> messages = repo.findMessages(Plaintext.Status.RECEIVED);

From c3d8a07e8385335856040bdfe8fdd13aa961ad5d Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 20 May 2016 23:00:27 +0200
Subject: [PATCH 15/20] Added unit tests and fixed bug

---
 .../dissem/bitmessage/entity/Plaintext.java   |  8 ++--
 .../bitmessage/BitmessageContextTest.java     | 25 ++++++++++--
 .../repository/JdbcMessageRepositoryTest.java | 38 +++++++++++++++++--
 3 files changed, 59 insertions(+), 12 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
index 90c3c50..4bfaba4 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.java
@@ -22,13 +22,11 @@ import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.factory.Factory;
-import ch.dissem.bitmessage.utils.Decode;
-import ch.dissem.bitmessage.utils.Encode;
-import ch.dissem.bitmessage.utils.TTL;
-import ch.dissem.bitmessage.utils.UnixTime;
+import ch.dissem.bitmessage.utils.*;
 
 import java.io.*;
 import java.util.*;
+import java.util.Collections;
 
 import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 
@@ -245,7 +243,7 @@ public class Plaintext implements Streamable {
     public void updateNextTry() {
         if (nextTry == null) {
             if (sent != null && to.has(Feature.DOES_ACK)) {
-                nextTry = sent + ttl;
+                nextTry = UnixTime.now(+ttl);
                 retries++;
             }
         } else {
diff --git a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
index 6e49853..5ad91cb 100644
--- a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
@@ -20,6 +20,7 @@ import ch.dissem.bitmessage.cryptography.bc.BouncyCryptography;
 import ch.dissem.bitmessage.entity.BitmessageAddress;
 import ch.dissem.bitmessage.entity.ObjectMessage;
 import ch.dissem.bitmessage.entity.Plaintext;
+import ch.dissem.bitmessage.entity.Plaintext.Type;
 import ch.dissem.bitmessage.entity.payload.ObjectType;
 import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
@@ -63,6 +64,7 @@ public class BitmessageContextTest {
                 .messageRepo(mock(MessageRepository.class))
                 .networkHandler(mock(NetworkHandler.class))
                 .nodeRegistry(mock(NodeRegistry.class))
+                .labeler(spy(new DefaultLabeler()))
                 .powRepo(spy(new ProofOfWorkRepository() {
                     Map<InventoryVector, Item> items = new HashMap<>();
 
@@ -205,7 +207,7 @@ public class BitmessageContextTest {
         assertEquals(2, ctx.internals().getProofOfWorkRepository().getItems().size());
         verify(ctx.internals().getProofOfWorkRepository(), timeout(10000).atLeastOnce())
                 .putObject(object(MSG), eq(1000L), eq(1000L));
-        verify(ctx.messages(), timeout(10000).atLeastOnce()).save(MessageMatchers.plaintext(Plaintext.Type.MSG));
+        verify(ctx.messages(), timeout(10000).atLeastOnce()).save(MessageMatchers.plaintext(Type.MSG));
     }
 
     @Test
@@ -215,7 +217,7 @@ public class BitmessageContextTest {
                 "Subject", "Message");
         verify(ctx.internals().getProofOfWorkRepository(), timeout(10000).atLeastOnce())
                 .putObject(object(GET_PUBKEY), eq(1000L), eq(1000L));
-        verify(ctx.messages(), timeout(10000).atLeastOnce()).save(MessageMatchers.plaintext(Plaintext.Type.MSG));
+        verify(ctx.messages(), timeout(10000).atLeastOnce()).save(MessageMatchers.plaintext(Type.MSG));
     }
 
     @Test(expected = IllegalArgumentException.class)
@@ -234,12 +236,12 @@ public class BitmessageContextTest {
         verify(ctx.internals().getProofOfWorkEngine())
                 .calculateNonce(any(byte[].class), any(byte[].class), any(ProofOfWorkEngine.Callback.class));
         verify(ctx.messages(), timeout(10000).atLeastOnce())
-                .save(MessageMatchers.plaintext(Plaintext.Type.BROADCAST));
+                .save(MessageMatchers.plaintext(Type.BROADCAST));
     }
 
     @Test(expected = IllegalArgumentException.class)
     public void ensureSenderWithoutPrivateKeyThrowsException() {
-        Plaintext msg = new Plaintext.Builder(Plaintext.Type.BROADCAST)
+        Plaintext msg = new Plaintext.Builder(Type.BROADCAST)
                 .from(new BitmessageAddress("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"))
                 .message("Subject", "Message")
                 .build();
@@ -295,4 +297,19 @@ public class BitmessageContextTest {
         assertEquals(chan.getVersion(), Pubkey.LATEST_VERSION);
         assertTrue(chan.isChan());
     }
+
+    @Test
+    public void ensureUnacknowledgedMessageIsResent() throws Exception {
+        Plaintext plaintext = new Plaintext.Builder(Type.MSG)
+                .ttl(1)
+                .message("subject", "message")
+                .from(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"))
+                .to(TestUtils.loadContact())
+                .build();
+        assertTrue(plaintext.getTo().has(Pubkey.Feature.DOES_ACK));
+        when(ctx.messages().findMessagesToResend()).thenReturn(Collections.singletonList(plaintext));
+        when(ctx.messages().getMessage(any(byte[].class))).thenReturn(plaintext);
+        ctx.internals().resendUnacknowledged();
+        verify(ctx.labeler(), timeout(1000).times(1)).markAsSent(eq(plaintext));
+    }
 }
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
index df8a42e..5fa88e7 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcMessageRepositoryTest.java
@@ -26,6 +26,8 @@ import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
 import ch.dissem.bitmessage.ports.AddressRepository;
 import ch.dissem.bitmessage.ports.MessageRepository;
+import ch.dissem.bitmessage.utils.UnixTime;
+import org.hamcrest.Matchers;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -36,6 +38,7 @@ import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
 import static ch.dissem.bitmessage.entity.payload.Pubkey.Feature.DOES_ACK;
 import static ch.dissem.bitmessage.utils.Singleton.cryptography;
 import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
 public class JdbcMessageRepositoryTest extends TestBase {
@@ -192,11 +195,40 @@ public class JdbcMessageRepositoryTest extends TestBase {
     }
 
     @Test
-    public void testRemove() throws Exception {
+    public void ensureMessageIsRemoved() throws Exception {
         Plaintext toRemove = repo.findMessages(Plaintext.Status.DRAFT, contactB).get(0);
-        repo.remove(toRemove);
         List<Plaintext> messages = repo.findMessages(Plaintext.Status.DRAFT);
-        assertEquals(1, messages.size());
+        assertEquals(2, messages.size());
+        repo.remove(toRemove);
+        messages = repo.findMessages(Plaintext.Status.DRAFT);
+        assertThat(messages, hasSize(1));
+    }
+
+    @Test
+    public void ensureUnacknowledgedMessagesAreFoundForResend() throws Exception {
+        Plaintext message = new Plaintext.Builder(MSG)
+                .IV(new InventoryVector(cryptography().randomBytes(32)))
+                .from(identity)
+                .to(contactA)
+                .message("Subject", "Message")
+                .status(Plaintext.Status.SENT)
+                .ttl(1)
+                .build();
+        message.updateNextTry();
+        assertThat(message.getRetries(), is(1));
+        assertThat(message.getNextTry(), greaterThan(UnixTime.now()));
+        assertThat(message.getNextTry(), lessThanOrEqualTo(UnixTime.now(+1)));
+        repo.save(message);
+        Thread.sleep(2100);
+        List<Plaintext> messagesToResend = repo.findMessagesToResend();
+        assertThat(messagesToResend, hasSize(1));
+
+        message.updateNextTry();
+        assertThat(message.getRetries(), is(2));
+        assertThat(message.getNextTry(), greaterThan(UnixTime.now()));
+        repo.save(message);
+        messagesToResend = repo.findMessagesToResend();
+        assertThat(messagesToResend, empty());
     }
 
     private void addMessage(BitmessageAddress from, BitmessageAddress to, Plaintext.Status status, Label... labels) {

From 14849a82ea67136190f6ce1699596fbc328f94fc Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Fri, 20 May 2016 23:58:08 +0200
Subject: [PATCH 16/20] Refactored JdbcMessageRepository so that alternative
 implementations can be done easier

---
 .gitignore                                    |   1 +
 .../ports/AbstractMessageRepository.java      | 123 +++++++++++++++++
 .../dissem/bitmessage/utils/SqlStrings.java   |  59 ++++++++
 .../bitmessage/utils/SqlStringsTest.java      |   8 +-
 .../bitmessage/repository/JdbcHelper.java     |  46 +------
 .../bitmessage/repository/JdbcInventory.java  |   1 +
 .../repository/JdbcMessageRepository.java     | 127 +++---------------
 7 files changed, 206 insertions(+), 159 deletions(-)
 create mode 100644 core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.java
 create mode 100644 core/src/main/java/ch/dissem/bitmessage/utils/SqlStrings.java
 rename repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcHelperTest.java => core/src/test/java/ch/dissem/bitmessage/utils/SqlStringsTest.java (81%)

diff --git a/.gitignore b/.gitignore
index fd29962..98d31cd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 ### Gradle ###
 .gradle
 build/
+classes/
 
 # Ignore Gradle GUI config
 gradle-app.setting
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.java b/core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.java
new file mode 100644
index 0000000..e037c4f
--- /dev/null
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.java
@@ -0,0 +1,123 @@
+/*
+ * Copyright 2016 Christian Basler
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package ch.dissem.bitmessage.ports;
+
+import ch.dissem.bitmessage.InternalContext;
+import ch.dissem.bitmessage.entity.BitmessageAddress;
+import ch.dissem.bitmessage.entity.Plaintext;
+import ch.dissem.bitmessage.entity.valueobject.Label;
+import ch.dissem.bitmessage.exception.ApplicationException;
+import ch.dissem.bitmessage.utils.Strings;
+import ch.dissem.bitmessage.utils.UnixTime;
+
+import java.util.Collection;
+import java.util.List;
+
+import static ch.dissem.bitmessage.utils.SqlStrings.join;
+
+public abstract class AbstractMessageRepository implements MessageRepository, InternalContext.ContextHolder {
+    protected InternalContext ctx;
+
+    @Override
+    public void setContext(InternalContext context) {
+        this.ctx = context;
+    }
+
+    protected void safeSenderIfNecessary(Plaintext message) {
+        if (message.getId() == null) {
+            BitmessageAddress savedAddress = ctx.getAddressRepository().getAddress(message.getFrom().getAddress());
+            if (savedAddress == null) {
+                ctx.getAddressRepository().save(message.getFrom());
+            } else if (savedAddress.getPubkey() == null && message.getFrom().getPubkey() != null) {
+                savedAddress.setPubkey(message.getFrom().getPubkey());
+                ctx.getAddressRepository().save(savedAddress);
+            }
+        }
+    }
+
+    @Override
+    public Plaintext getMessage(Object id) {
+        if (id instanceof Long) {
+            return single(find("id=" + id));
+        } else {
+            throw new IllegalArgumentException("Long expected for ID");
+        }
+    }
+
+    @Override
+    public Plaintext getMessage(byte[] initialHash) {
+        return single(find("initial_hash=X'" + Strings.hex(initialHash) + "'"));
+    }
+
+    @Override
+    public Plaintext getMessageForAck(byte[] ackData) {
+        return single(find("ack_data=X'" + Strings.hex(ackData) + "' AND status='" + Plaintext.Status.SENT + "'"));
+    }
+
+    @Override
+    public List<Plaintext> findMessages(Label label) {
+        return find("id IN (SELECT message_id FROM Message_Label WHERE label_id=" + label.getId() + ")");
+    }
+
+    @Override
+    public List<Plaintext> findMessages(Plaintext.Status status, BitmessageAddress recipient) {
+        return find("status='" + status.name() + "' AND recipient='" + recipient.getAddress() + "'");
+    }
+
+    @Override
+    public List<Plaintext> findMessages(Plaintext.Status status) {
+        return find("status='" + status.name() + "'");
+    }
+
+    @Override
+    public List<Plaintext> findMessages(BitmessageAddress sender) {
+        return find("sender='" + sender.getAddress() + "'");
+    }
+
+    @Override
+    public List<Plaintext> findMessagesToResend() {
+        return find("status='" + Plaintext.Status.SENT.name() + "'" +
+                " AND next_try < " + UnixTime.now());
+    }
+
+    @Override
+    public List<Label> getLabels() {
+        return findLabels("1=1");
+    }
+
+    @Override
+    public List<Label> getLabels(Label.Type... types) {
+        return findLabels("type IN (" + join(types) + ")");
+    }
+
+    protected abstract List<Label> findLabels(String where);
+
+
+    protected <T> T single(Collection<T> collection) {
+        switch (collection.size()) {
+            case 0:
+                return null;
+            case 1:
+                return collection.iterator().next();
+            default:
+                throw new ApplicationException("This shouldn't happen, found " + collection.size() +
+                        " items, one or none was expected");
+        }
+    }
+
+    protected abstract List<Plaintext> find(String where);
+}
diff --git a/core/src/main/java/ch/dissem/bitmessage/utils/SqlStrings.java b/core/src/main/java/ch/dissem/bitmessage/utils/SqlStrings.java
new file mode 100644
index 0000000..82d06e3
--- /dev/null
+++ b/core/src/main/java/ch/dissem/bitmessage/utils/SqlStrings.java
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2016 Christian Basler
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package ch.dissem.bitmessage.utils;
+
+import ch.dissem.bitmessage.entity.payload.ObjectType;
+
+import static ch.dissem.bitmessage.utils.Strings.hex;
+
+public class SqlStrings {
+    public static StringBuilder join(long... objects) {
+        StringBuilder streamList = new StringBuilder();
+        for (int i = 0; i < objects.length; i++) {
+            if (i > 0) streamList.append(", ");
+            streamList.append(objects[i]);
+        }
+        return streamList;
+    }
+
+    public static StringBuilder join(byte[]... objects) {
+        StringBuilder streamList = new StringBuilder();
+        for (int i = 0; i < objects.length; i++) {
+            if (i > 0) streamList.append(", ");
+            streamList.append(hex(objects[i]));
+        }
+        return streamList;
+    }
+
+    public static StringBuilder join(ObjectType... types) {
+        StringBuilder streamList = new StringBuilder();
+        for (int i = 0; i < types.length; i++) {
+            if (i > 0) streamList.append(", ");
+            streamList.append(types[i].getNumber());
+        }
+        return streamList;
+    }
+
+    public static StringBuilder join(Enum... types) {
+        StringBuilder streamList = new StringBuilder();
+        for (int i = 0; i < types.length; i++) {
+            if (i > 0) streamList.append(", ");
+            streamList.append('\'').append(types[i].name()).append('\'');
+        }
+        return streamList;
+    }
+}
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcHelperTest.java b/core/src/test/java/ch/dissem/bitmessage/utils/SqlStringsTest.java
similarity index 81%
rename from repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcHelperTest.java
rename to core/src/test/java/ch/dissem/bitmessage/utils/SqlStringsTest.java
index ee3a580..2aa1113 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcHelperTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/utils/SqlStringsTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Christian Basler
+ * Copyright 2016 Christian Basler
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,16 +14,16 @@
  * limitations under the License.
  */
 
-package ch.dissem.bitmessage.repository;
+package ch.dissem.bitmessage.utils;
 
 import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
 
-public class JdbcHelperTest {
+public class SqlStringsTest {
     @Test
     public void ensureJoinWorksWithLongArray() {
         long[] test = {1L, 2L};
-        assertEquals("1, 2", JdbcHelper.join(test).toString());
+        assertEquals("1, 2", SqlStrings.join(test).toString());
     }
 }
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java
index beb4c80..b0be9c1 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcHelper.java
@@ -42,43 +42,7 @@ public abstract class JdbcHelper {
         this.config = config;
     }
 
-    public static StringBuilder join(long... objects) {
-        StringBuilder streamList = new StringBuilder();
-        for (int i = 0; i < objects.length; i++) {
-            if (i > 0) streamList.append(", ");
-            streamList.append(objects[i]);
-        }
-        return streamList;
-    }
-
-    public static StringBuilder join(byte[]... objects) {
-        StringBuilder streamList = new StringBuilder();
-        for (int i = 0; i < objects.length; i++) {
-            if (i > 0) streamList.append(", ");
-            streamList.append(hex(objects[i]));
-        }
-        return streamList;
-    }
-
-    public static StringBuilder join(ObjectType... types) {
-        StringBuilder streamList = new StringBuilder();
-        for (int i = 0; i < types.length; i++) {
-            if (i > 0) streamList.append(", ");
-            streamList.append(types[i].getNumber());
-        }
-        return streamList;
-    }
-
-    public static StringBuilder join(Enum... types) {
-        StringBuilder streamList = new StringBuilder();
-        for (int i = 0; i < types.length; i++) {
-            if (i > 0) streamList.append(", ");
-            streamList.append('\'').append(types[i].name()).append('\'');
-        }
-        return streamList;
-    }
-
-    protected void writeBlob(PreparedStatement ps, int parameterIndex, Streamable data) throws SQLException, IOException {
+    public static void writeBlob(PreparedStatement ps, int parameterIndex, Streamable data) throws SQLException, IOException {
         if (data == null) {
             ps.setBytes(parameterIndex, null);
         } else {
@@ -87,12 +51,4 @@ public abstract class JdbcHelper {
             ps.setBytes(parameterIndex, os.toByteArray());
         }
     }
-
-    protected <T> T single(Collection<T> collection) {
-        if (collection.size() > 1) {
-            throw new ApplicationException("This shouldn't happen, found " + collection.size() +
-                    " messages, one or none was expected");
-        }
-        return collection.stream().findAny().orElse(null);
-    }
 }
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcInventory.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcInventory.java
index 0cc9f3b..13d3725 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcInventory.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcInventory.java
@@ -31,6 +31,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import static ch.dissem.bitmessage.utils.SqlStrings.join;
 import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
 import static ch.dissem.bitmessage.utils.UnixTime.now;
 
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
index 7ac42f9..403754a 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
@@ -16,16 +16,12 @@
 
 package ch.dissem.bitmessage.repository;
 
-import ch.dissem.bitmessage.InternalContext;
-import ch.dissem.bitmessage.entity.BitmessageAddress;
 import ch.dissem.bitmessage.entity.Plaintext;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.entity.valueobject.Label;
 import ch.dissem.bitmessage.exception.ApplicationException;
+import ch.dissem.bitmessage.ports.AbstractMessageRepository;
 import ch.dissem.bitmessage.ports.MessageRepository;
-import ch.dissem.bitmessage.utils.Strings;
-import ch.dissem.bitmessage.utils.TTL;
-import ch.dissem.bitmessage.utils.UnixTime;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -33,34 +29,30 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.sql.*;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
 
-public class JdbcMessageRepository extends JdbcHelper implements MessageRepository, InternalContext.ContextHolder {
+import static ch.dissem.bitmessage.repository.JdbcHelper.writeBlob;
+
+public class JdbcMessageRepository extends AbstractMessageRepository implements MessageRepository {
     private static final Logger LOG = LoggerFactory.getLogger(JdbcMessageRepository.class);
 
-    private InternalContext ctx;
+    private final JdbcConfig config;
 
     public JdbcMessageRepository(JdbcConfig config) {
-        super(config);
+        this.config = config;
     }
 
     @Override
-    public List<Label> getLabels() {
-        List<Label> result = new LinkedList<>();
+    protected List<Label> findLabels(String where) {
         try (
-                Connection connection = config.getConnection();
-                Statement stmt = connection.createStatement();
-                ResultSet rs = stmt.executeQuery("SELECT id, label, type, color FROM Label ORDER BY ord")
+                Connection connection = config.getConnection()
         ) {
-            while (rs.next()) {
-                result.add(getLabel(rs));
-            }
+            return findLabels(connection, where);
         } catch (SQLException e) {
-            throw new ApplicationException(e);
+            LOG.error(e.getMessage(), e);
         }
-        return result;
+        return new ArrayList<>();
     }
 
     private Label getLabel(ResultSet rs) throws SQLException {
@@ -75,24 +67,6 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
         return label;
     }
 
-    @Override
-    public List<Label> getLabels(Label.Type... types) {
-        List<Label> result = new LinkedList<>();
-        try (
-                Connection connection = config.getConnection();
-                Statement stmt = connection.createStatement();
-                ResultSet rs = stmt.executeQuery("SELECT id, label, type, color FROM Label WHERE type IN (" + join(types) +
-                        ") ORDER BY ord")
-        ) {
-            while (rs.next()) {
-                result.add(getLabel(rs));
-            }
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-        return result;
-    }
-
     @Override
     public int countUnread(Label label) {
         String where;
@@ -120,60 +94,7 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
     }
 
     @Override
-    public Plaintext getMessage(Object id) {
-        if (id instanceof Long) {
-            List<Plaintext> plaintexts = find("id=" + id);
-            switch (plaintexts.size()) {
-                case 0:
-                    return null;
-                case 1:
-                    return plaintexts.get(0);
-                default:
-                    throw new ApplicationException("This shouldn't happen, found " + plaintexts.size() +
-                            " messages, one or none was expected");
-            }
-        } else {
-            throw new IllegalArgumentException("Long expected for ID");
-        }
-    }
-
-    @Override
-    public Plaintext getMessage(byte[] initialHash) {
-        return single(find("initial_hash=X'" + Strings.hex(initialHash) + "'"));
-    }
-
-    @Override
-    public Plaintext getMessageForAck(byte[] ackData) {
-        return single(find("ack_data=X'" + Strings.hex(ackData) + "' AND status='" + Plaintext.Status.SENT + "'"));
-    }
-
-    @Override
-    public List<Plaintext> findMessages(Label label) {
-        return find("id IN (SELECT message_id FROM Message_Label WHERE label_id=" + label.getId() + ")");
-    }
-
-    @Override
-    public List<Plaintext> findMessages(Plaintext.Status status, BitmessageAddress recipient) {
-        return find("status='" + status.name() + "' AND recipient='" + recipient.getAddress() + "'");
-    }
-
-    @Override
-    public List<Plaintext> findMessages(Plaintext.Status status) {
-        return find("status='" + status.name() + "'");
-    }
-
-    @Override
-    public List<Plaintext> findMessages(BitmessageAddress sender) {
-        return find("sender='" + sender.getAddress() + "'");
-    }
-
-    @Override
-    public List<Plaintext> findMessagesToResend() {
-        return find("status='" + Plaintext.Status.SENT.name() + "'" +
-                " AND next_try < " + UnixTime.now());
-    }
-
-    private List<Plaintext> find(String where) {
+    protected List<Plaintext> find(String where) {
         List<Plaintext> result = new LinkedList<>();
         try (
                 Connection connection = config.getConnection();
@@ -199,7 +120,8 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
                 builder.ttl(rs.getLong("ttl"));
                 builder.retries(rs.getInt("retries"));
                 builder.nextTry(rs.getLong("next_try"));
-                builder.labels(findLabels(connection, id));
+                builder.labels(findLabels(connection,
+                        "WHERE id IN (SELECT label_id FROM Message_Label WHERE message_id=" + id + ") ORDER BY ord"));
                 Plaintext message = builder.build();
                 message.setInitialHash(rs.getBytes("initial_hash"));
                 result.add(message);
@@ -210,12 +132,11 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
         return result;
     }
 
-    private Collection<Label> findLabels(Connection connection, long messageId) {
+    private List<Label> findLabels(Connection connection, String where) {
         List<Label> result = new ArrayList<>();
         try (
                 Statement stmt = connection.createStatement();
-                ResultSet rs = stmt.executeQuery("SELECT id, label, type, color FROM Label " +
-                        "WHERE id IN (SELECT label_id FROM Message_Label WHERE message_id=" + messageId + ")")
+                ResultSet rs = stmt.executeQuery("SELECT id, label, type, color FROM Label WHERE " + where)
         ) {
             while (rs.next()) {
                 result.add(getLabel(rs));
@@ -228,16 +149,7 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
 
     @Override
     public void save(Plaintext message) {
-        // save from address if necessary
-        if (message.getId() == null) {
-            BitmessageAddress savedAddress = ctx.getAddressRepository().getAddress(message.getFrom().getAddress());
-            if (savedAddress == null) {
-                ctx.getAddressRepository().save(message.getFrom());
-            } else if (savedAddress.getPubkey() == null && message.getFrom().getPubkey() != null) {
-                savedAddress.setPubkey(message.getFrom().getPubkey());
-                ctx.getAddressRepository().save(savedAddress);
-            }
-        }
+        safeSenderIfNecessary(message);
 
         try (Connection connection = config.getConnection()) {
             try {
@@ -350,9 +262,4 @@ public class JdbcMessageRepository extends JdbcHelper implements MessageReposito
             LOG.error(e.getMessage(), e);
         }
     }
-
-    @Override
-    public void setContext(InternalContext context) {
-        this.ctx = context;
-    }
 }

From ed6344c6627ddd11a128aaa670f3364bdead5c47 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Mon, 23 May 2016 20:11:44 +0200
Subject: [PATCH 17/20] Added BitmessageContext method to resent unacknowledged
 messages and updated README.md

---
 README.md                                     | 50 +++++++++++++------
 .../dissem/bitmessage/BitmessageContext.java  | 23 +++++++++
 .../bitmessage/BitmessageContextTest.java     |  2 +-
 3 files changed, 60 insertions(+), 15 deletions(-)

diff --git a/README.md b/README.md
index 6c44558..fd9d955 100644
--- a/README.md
+++ b/README.md
@@ -5,10 +5,10 @@ Jabit
 [![Apache 2](https://img.shields.io/badge/license-Apache_2.0-blue.svg)](https://raw.githubusercontent.com/Dissem/Jabit/master/LICENSE)
 [![Visit our IRC channel](https://img.shields.io/badge/irc-%23jabit-blue.svg)](https://kiwiirc.com/client/irc.freenode.net/#jabit)
 
-A Java implementation for the Bitmessage protocol. To build, use command `gradle build` or `./gradlew build`.
+A Java implementation for the Bitmessage protocol. To build, use command
+`gradle build` or `./gradlew build`.
 
-Please note that it still has its limitations, but the API should now be stable. Jabit uses Semantic Versioning, meaning
-as long as the major version doesn't change, nothing should break if you update.
+Please note that it still has its limitations, but the API should now be stable. Jabit uses Semantic Versioning, meaning as long as the major version doesn't change, nothing should break if you update.
 
 #### Master
 [![Build Status](https://travis-ci.org/Dissem/Jabit.svg?branch=master)](https://travis-ci.org/Dissem/Jabit) 
@@ -23,9 +23,7 @@ as long as the major version doesn't change, nothing should break if you update.
 Security
 --------
 
-There are most probably some security issues, me programming this thing all by myself. Jabit doesn't do anything against
-timing attacks yet, for example. Please feel free to use the library, report bugs and maybe even help out. I hope the
-code is easy to understand and work with.
+There are most probably some security issues, me programming this thing all by myself. Jabit doesn't do anything against timing attacks yet, for example. Please feel free to use the library, report bugs and maybe even help out. I hope the code is easy to understand and work with.
 
 Project Status
 --------------
@@ -74,17 +72,22 @@ BitmessageContext ctx = new BitmessageContext.Builder()
         .nodeRegistry(new MemoryNodeRegistry())
         .networkHandler(new NetworkNode())
         .cryptography(new BouncyCryptography())
+        .listener(System.out::println)
         .build();
 ```
-This creates a simple context using a H2 database that will be created in the user's home directory. Next you'll need to
-start the context and decide what happens if a message arrives:
+This creates a simple context using a H2 database that will be created in the user's home directory. In the listener you decide what happens when a message arrives. If you can't use lambdas, you may instead write
 ```Java
-ctx.startup(new BitmessageContext.Listener() {
-    @Override
-    public void receive(Plaintext plaintext) {
-        // TODO: Notify the user
-    }
-});
+        .listener(new BitmessageContext.Listener() {
+            @Override
+            public void receive(Plaintext plaintext) {
+                // TODO: Notify the user
+            }
+        })
+```
+
+Next you'll need to start the context:
+```Java
+ctx.startup()
 ```
 Then you might want to create an identity
 ```Java
@@ -100,3 +103,22 @@ to which you can send some messages
 ```Java
 ctx.send(identity, contact, "Test", "Hello Chris, this is a message.");
 ```
+
+### Housekeeping
+
+As Bitmessage stores all currently valid messages, we'll need to delete expired objects from time to time:
+```Java
+ctx.cleanup();
+```
+If the client runs all the time, it might be a good idea to do this daily or at least weekly. Otherwise, you might just want to clean up on shutdown.
+
+Also, if some messages weren't acknowledged when it expired, they can be resent:
+```Java
+ctx.resendUnacknowledgedMessages();
+```
+This could be triggered periodically, or manually by the user. Please be aware that _if_ there is a message to resend, proof of work needs to be calculated, so to not annoy your users you might not want to trigger it on shutdown. As the client might have been offline for some time, it might as well be wise to wait until it caught up downloading new messages before resending those messages, after all they might be acknowledged by now.
+
+There probably won't happen extremely bad things if you don't - at least not more than otherwise - but you can properly shutdown the network connection by calling
+```Java
+ctx.shutdown();
+```
diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index ad21e72..032431d 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -221,10 +221,33 @@ public class BitmessageContext {
         return ctx.getNetworkHandler().send(server, port, request);
     }
 
+    /**
+     * Removes expired objects from the inventory. You should call this method regularly,
+     * e.g. daily and on each shutdown.
+     */
     public void cleanup() {
         ctx.getInventory().cleanup();
     }
 
+    /**
+     * Sends messages again whose time to live expired without being acknowledged. (And whose
+     * recipient is expected to send acknowledgements.
+     * <p>
+     *     You should call this method regularly, but be aware of the following:
+     *     <ul>
+     *         <li>As messages might be sent, POW will be done. It is therefore not advised to
+     *         call it on shutdown.</li>
+     *         <li>It shouldn't be called right after startup, as it's possible the missing
+     *         acknowledgement was sent while the client was offline.</li>
+     *         <li>Other than that, the call isn't expensive as long as there is no message
+     *         to send, so it might be a good idea to just call it every few minutes.</li>
+     *     </ul>
+     * </p>
+     */
+    public void resendUnacknowledgedMessages() {
+        ctx.resendUnacknowledged();
+    }
+
     public boolean isRunning() {
         return ctx.getNetworkHandler().isRunning();
     }
diff --git a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
index 5ad91cb..813ff20 100644
--- a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.java
@@ -309,7 +309,7 @@ public class BitmessageContextTest {
         assertTrue(plaintext.getTo().has(Pubkey.Feature.DOES_ACK));
         when(ctx.messages().findMessagesToResend()).thenReturn(Collections.singletonList(plaintext));
         when(ctx.messages().getMessage(any(byte[].class))).thenReturn(plaintext);
-        ctx.internals().resendUnacknowledged();
+        ctx.resendUnacknowledgedMessages();
         verify(ctx.labeler(), timeout(1000).times(1)).markAsSent(eq(plaintext));
     }
 }

From 409dccd0beba0215ee899365a10edd0bed517cdd Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Tue, 24 May 2016 07:45:34 +0200
Subject: [PATCH 18/20] Fixed broken JavaDoc and removed unused import

---
 .../dissem/bitmessage/BitmessageContext.java  | 19 +++++++++----------
 .../entity/payload/ObjectPayload.java         |  1 -
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index 032431d..1b9b402 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -233,16 +233,15 @@ public class BitmessageContext {
      * Sends messages again whose time to live expired without being acknowledged. (And whose
      * recipient is expected to send acknowledgements.
      * <p>
-     *     You should call this method regularly, but be aware of the following:
-     *     <ul>
-     *         <li>As messages might be sent, POW will be done. It is therefore not advised to
-     *         call it on shutdown.</li>
-     *         <li>It shouldn't be called right after startup, as it's possible the missing
-     *         acknowledgement was sent while the client was offline.</li>
-     *         <li>Other than that, the call isn't expensive as long as there is no message
-     *         to send, so it might be a good idea to just call it every few minutes.</li>
-     *     </ul>
-     * </p>
+     * You should call this method regularly, but be aware of the following:
+     * <ul>
+     * <li>As messages might be sent, POW will be done. It is therefore not advised to
+     * call it on shutdown.</li>
+     * <li>It shouldn't be called right after startup, as it's possible the missing
+     * acknowledgement was sent while the client was offline.</li>
+     * <li>Other than that, the call isn't expensive as long as there is no message
+     * to send, so it might be a good idea to just call it every few minutes.</li>
+     * </ul>
      */
     public void resendUnacknowledgedMessages() {
         ctx.resendUnacknowledged();
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java b/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java
index a7dbaff..33da28d 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/ObjectPayload.java
@@ -18,7 +18,6 @@ package ch.dissem.bitmessage.entity.payload;
 
 import ch.dissem.bitmessage.entity.ObjectMessage;
 import ch.dissem.bitmessage.entity.Streamable;
-import sun.reflect.generics.reflectiveObjects.NotImplementedException;
 
 import java.io.IOException;
 import java.io.OutputStream;

From 725d2b848e018cc8995feccf4a95c18bb5510f14 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Tue, 24 May 2016 17:19:29 +0200
Subject: [PATCH 19/20] Fixed migration and added resend and cleanup options to
 demo application

---
 .../dissem/bitmessage/BitmessageContext.java  |  3 ++-
 .../dissem/bitmessage/demo/Application.java   | 23 +++++++++++++++++--
 .../migration/V3.2__Update_table_message.sql  |  2 +-
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index 1b9b402..b06cf9a 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -281,7 +281,8 @@ public class BitmessageContext {
 
     public Property status() {
         return new Property("status", null,
-                ctx.getNetworkHandler().getNetworkStatus()
+                ctx.getNetworkHandler().getNetworkStatus(),
+                new Property("unacknowledged", ctx.getMessageRepository().findMessagesToResend().size())
         );
     }
 
diff --git a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
index 89b91dc..583669b 100644
--- a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
+++ b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
@@ -118,8 +118,27 @@ public class Application {
     }
 
     private void info() {
-        System.out.println();
-        System.out.println(ctx.status());
+        String command;
+        do {
+            System.out.println();
+            System.out.println(ctx.status());
+            System.out.println();
+            System.out.println("c) cleanup inventory");
+            System.out.println("r) resend unacknowledged messages");
+            System.out.println(COMMAND_BACK);
+
+            command = commandLine.nextCommand();
+            switch (command) {
+                case "c":
+                    ctx.cleanup();
+                    break;
+                case "r":
+                    ctx.resendUnacknowledgedMessages();
+                    break;
+                case "b":
+                    return;
+            }
+        } while (!"b".equals(command));
     }
 
     private void identities() {
diff --git a/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql b/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
index 38847cf..1eba39f 100644
--- a/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
+++ b/repositories/src/main/resources/db/migration/V3.2__Update_table_message.sql
@@ -1,4 +1,4 @@
 ALTER TABLE Message ADD COLUMN ack_data BINARY(32);
-ALTER TABLE Message ADD COLUMN ttl      BIGINT NOT NULL;
+ALTER TABLE Message ADD COLUMN ttl      BIGINT NOT NULL DEFAULT 0;
 ALTER TABLE Message ADD COLUMN retries  INT NOT NULL DEFAULT 0;
 ALTER TABLE Message ADD COLUMN next_try BIGINT;

From 22108527f3083696328ec7c00355d078470ca104 Mon Sep 17 00:00:00 2001
From: Christian Basler <chrigu.meyer@gmail.com>
Date: Tue, 24 May 2016 19:35:41 +0200
Subject: [PATCH 20/20] Minor update to the README file

---
 README.md | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index fd9d955..16a2528 100644
--- a/README.md
+++ b/README.md
@@ -5,11 +5,12 @@ Jabit
 [![Apache 2](https://img.shields.io/badge/license-Apache_2.0-blue.svg)](https://raw.githubusercontent.com/Dissem/Jabit/master/LICENSE)
 [![Visit our IRC channel](https://img.shields.io/badge/irc-%23jabit-blue.svg)](https://kiwiirc.com/client/irc.freenode.net/#jabit)
 
-A Java implementation for the Bitmessage protocol. To build, use command
-`gradle build` or `./gradlew build`.
+A Java implementation for the Bitmessage protocol. To build, use command `./gradlew build`.
 
 Please note that it still has its limitations, but the API should now be stable. Jabit uses Semantic Versioning, meaning as long as the major version doesn't change, nothing should break if you update.
 
+Be aware though that this doesn't necessarily applies for SNAPSHOT builds and the development branch, notably when it comes to database updates. _In other words, they may break your installation!_ 
+
 #### Master
 [![Build Status](https://travis-ci.org/Dissem/Jabit.svg?branch=master)](https://travis-ci.org/Dissem/Jabit) 
 [![Code Quality](https://img.shields.io/codacy/e9938d2adbb74a0db553115bef692ff3/master.svg)](https://www.codacy.com/app/chrigu-meyer/Jabit/dashboard?bid=3144281)