diff --git a/README.md b/README.md
index dcbffa4..75f2b28 100644
--- a/README.md
+++ b/README.md
@@ -84,7 +84,7 @@ BitmessageContext ctx = new BitmessageContext.Builder()
         .powRepo(new JdbcProofOfWorkRepository(jdbcConfig))
         .nodeRegistry(new JdbcNodeRegistry(jdbcConfig))
         .networkHandler(new NioNetworkHandler())
-        .cryptography(BouncyCryptography.INSTANCE)
+        .cryptography(new BouncyCryptography())
         .listener(System.out::println)
         .build();
 ```
diff --git a/build.gradle b/build.gradle
index 26aa243..02fa2b4 100644
--- a/build.gradle
+++ b/build.gradle
@@ -29,6 +29,7 @@ subprojects {
     }
     dependencies {
         compile "org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
+        compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
     }
 
     test {
diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.kt b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.kt
index 175e378..f3ffa6c 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.kt
@@ -58,7 +58,53 @@ import kotlin.properties.Delegates
  *
  * The port defaults to 8444 (the default Bitmessage port)
  */
-class BitmessageContext private constructor(builder: BitmessageContext.Builder) {
+class BitmessageContext(
+    cryptography: Cryptography,
+    inventory: Inventory,
+    nodeRegistry: NodeRegistry,
+    networkHandler: NetworkHandler,
+    addressRepository: AddressRepository,
+    messageRepository: MessageRepository,
+    proofOfWorkRepository: ProofOfWorkRepository,
+    proofOfWorkEngine: ProofOfWorkEngine = MultiThreadedPOWEngine(),
+    customCommandHandler: CustomCommandHandler = object : CustomCommandHandler {
+        override fun handle(request: CustomMessage): MessagePayload? {
+            BitmessageContext.LOG.debug("Received custom request, but no custom command handler configured.")
+            return null
+        }
+    },
+    listener: Listener,
+    labeler: Labeler = DefaultLabeler(),
+    port: Int = 8444,
+    connectionTTL: Long = 30 * MINUTE,
+    connectionLimit: Int = 150,
+    sendPubkeyOnIdentityCreation: Boolean,
+    doMissingProofOfWorkDelayInSeconds: Int = 30
+) {
+
+    private constructor(builder: BitmessageContext.Builder) : this(
+        builder.cryptography,
+        builder.inventory,
+        builder.nodeRegistry,
+        builder.networkHandler,
+        builder.addressRepo,
+        builder.messageRepo,
+        builder.proofOfWorkRepository,
+        builder.proofOfWorkEngine ?: MultiThreadedPOWEngine(),
+        builder.customCommandHandler ?: object : CustomCommandHandler {
+            override fun handle(request: CustomMessage): MessagePayload? {
+                BitmessageContext.LOG.debug("Received custom request, but no custom command handler configured.")
+                return null
+            }
+        },
+        builder.listener,
+        builder.labeler ?: DefaultLabeler(),
+        builder.port,
+        builder.connectionTTL,
+        builder.connectionLimit,
+        builder.sendPubkeyOnIdentityCreation,
+        builder.doMissingProofOfWorkDelay
+    )
 
     private val sendPubkeyOnIdentityCreation: Boolean
 
@@ -72,38 +118,10 @@ class BitmessageContext private constructor(builder: BitmessageContext.Builder)
     val labeler: Labeler
         @JvmName("labeler") get
 
-    init {
-        labeler = builder.labeler ?: DefaultLabeler()
-        internals = InternalContext(
-            builder.cryptography,
-            builder.inventory,
-            builder.nodeRegistry,
-            builder.networkHandler,
-            builder.addressRepo,
-            builder.messageRepo,
-            builder.proofOfWorkRepository,
-            builder.proofOfWorkEngine ?: MultiThreadedPOWEngine(),
-            builder.customCommandHandler ?: object : CustomCommandHandler {
-                override fun handle(request: CustomMessage): MessagePayload? {
-                    LOG.debug("Received custom request, but no custom command handler configured.")
-                    return null
-                }
-            },
-            builder.listener,
-            labeler,
-            builder.port,
-            builder.connectionTTL,
-            builder.connectionLimit
-        )
-        internals.proofOfWorkService.doMissingProofOfWork(30000) // TODO: this should be configurable
-        sendPubkeyOnIdentityCreation = builder.sendPubkeyOnIdentityCreation
-        (builder.listener as? Listener.WithContext)?.setContext(this)
-    }
-
-    val addresses: AddressRepository = internals.addressRepository
+    val addresses: AddressRepository
         @JvmName("addresses") get
 
-    val messages: MessageRepository = internals.messageRepository
+    val messages: MessageRepository
         @JvmName("messages") get
 
     fun createIdentity(shorter: Boolean, vararg features: Feature): BitmessageAddress {
@@ -285,10 +303,9 @@ class BitmessageContext private constructor(builder: BitmessageContext.Builder)
     fun addContact(contact: BitmessageAddress) {
         internals.addressRepository.save(contact)
         if (contact.pubkey == null) {
-            internals.addressRepository.getAddress(contact.address)?.let {
-                if (it.pubkey == null) {
-                    internals.requestPubkey(contact)
-                }
+            // If it already existed, the saved contact might have the public key
+            if (internals.addressRepository.getAddress(contact.address)!!.pubkey == null) {
+                internals.requestPubkey(contact)
             }
         }
     }
@@ -300,13 +317,13 @@ class BitmessageContext private constructor(builder: BitmessageContext.Builder)
     }
 
     private fun tryToFindBroadcastsForAddress(address: BitmessageAddress) {
-        for (`object` in internals.inventory.getObjects(address.stream, Broadcast.getVersion(address), ObjectType.BROADCAST)) {
+        for (objectMessage in internals.inventory.getObjects(address.stream, Broadcast.getVersion(address), ObjectType.BROADCAST)) {
             try {
-                val broadcast = `object`.payload as Broadcast
+                val broadcast = objectMessage.payload as Broadcast
                 broadcast.decrypt(address)
                 // This decrypts it twice, but on the other hand it doesn't try to decrypt the objects with
                 // other subscriptions and the interface stays as simple as possible.
-                internals.networkListener.receive(`object`)
+                internals.networkListener.receive(objectMessage)
             } catch (ignore: DecryptionFailedException) {
             } catch (e: Exception) {
                 LOG.debug(e.message, e)
@@ -348,6 +365,7 @@ class BitmessageContext private constructor(builder: BitmessageContext.Builder)
         internal var connectionLimit = 150
         internal var connectionTTL = 30 * MINUTE
         internal var sendPubkeyOnIdentityCreation = true
+        internal var doMissingProofOfWorkDelay = 30
 
         fun port(port: Int): Builder {
             this.port = port
@@ -409,6 +427,7 @@ class BitmessageContext private constructor(builder: BitmessageContext.Builder)
             return this
         }
 
+        @JvmName("kotlinListener")
         fun listener(listener: (Plaintext) -> Unit): Builder {
             this.listener = object : Listener {
                 override fun receive(plaintext: Plaintext) {
@@ -428,6 +447,10 @@ class BitmessageContext private constructor(builder: BitmessageContext.Builder)
             return this
         }
 
+        fun doMissingProofOfWorkDelay(seconds: Int) {
+            this.doMissingProofOfWorkDelay = seconds
+        }
+
         /**
          * By default a client will send the public key when an identity is being created. On weaker devices
          * this behaviour might not be desirable.
@@ -438,18 +461,34 @@ class BitmessageContext private constructor(builder: BitmessageContext.Builder)
         }
 
         fun build(): BitmessageContext {
-            nonNull("inventory", inventory)
-            nonNull("nodeRegistry", nodeRegistry)
-            nonNull("networkHandler", networkHandler)
-            nonNull("addressRepo", addressRepo)
-            nonNull("messageRepo", messageRepo)
-            nonNull("proofOfWorkRepo", proofOfWorkRepository)
             return BitmessageContext(this)
         }
+    }
 
-        private fun nonNull(name: String, o: Any?) {
-            if (o == null) throw IllegalStateException(name + " must not be null")
-        }
+
+    init {
+        this.labeler = labeler
+        this.internals = InternalContext(
+            cryptography,
+            inventory,
+            nodeRegistry,
+            networkHandler,
+            addressRepository,
+            messageRepository,
+            proofOfWorkRepository,
+            proofOfWorkEngine,
+            customCommandHandler,
+            listener,
+            labeler,
+            port,
+            connectionTTL,
+            connectionLimit
+        )
+        this.addresses = addressRepository
+        this.messages = messageRepository
+        this.sendPubkeyOnIdentityCreation = sendPubkeyOnIdentityCreation
+        (listener as? Listener.WithContext)?.setContext(this)
+        internals.proofOfWorkService.doMissingProofOfWork(doMissingProofOfWorkDelayInSeconds * 1000L)
     }
 
     companion object {
diff --git a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.kt b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.kt
index 35a7628..37c2a75 100644
--- a/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/DefaultMessageListener.kt
@@ -25,6 +25,7 @@ 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.Strings.hex
 import org.slf4j.LoggerFactory
 import java.util.*
 
@@ -32,23 +33,23 @@ internal open class DefaultMessageListener(
     private val labeler: Labeler,
     private val listener: BitmessageContext.Listener
 ) : NetworkHandler.MessageListener {
-    private var ctx by InternalContext
+    private var ctx by InternalContext.lateinit
 
-    override fun receive(`object`: ObjectMessage) {
-        val payload = `object`.payload
+    override fun receive(objectMessage: ObjectMessage) {
+        val payload = objectMessage.payload
 
         when (payload.type) {
             ObjectType.GET_PUBKEY -> {
-                receive(`object`, payload as GetPubkey)
+                receive(objectMessage, payload as GetPubkey)
             }
             ObjectType.PUBKEY -> {
-                receive(`object`, payload as Pubkey)
+                receive(objectMessage, payload as Pubkey)
             }
             ObjectType.MSG -> {
-                receive(`object`, payload as Msg)
+                receive(objectMessage, payload as Msg)
             }
             ObjectType.BROADCAST -> {
-                receive(`object`, payload as Broadcast)
+                receive(objectMessage, payload as Broadcast)
             }
             null -> {
                 if (payload is GenericPayload) {
@@ -61,30 +62,33 @@ internal open class DefaultMessageListener(
         }
     }
 
-    protected fun receive(`object`: ObjectMessage, getPubkey: GetPubkey) {
+    protected fun receive(objectMessage: ObjectMessage, getPubkey: GetPubkey) {
         val identity = ctx.addressRepository.findIdentity(getPubkey.ripeTag)
         if (identity != null && identity.privateKey != null && !identity.isChan) {
             LOG.info("Got pubkey request for identity " + identity)
             // FIXME: only send pubkey if it wasn't sent in the last TTL.pubkey() days
-            ctx.sendPubkey(identity, `object`.stream)
+            ctx.sendPubkey(identity, objectMessage.stream)
         }
     }
 
-    protected fun receive(`object`: ObjectMessage, pubkey: Pubkey) {
-        val address: BitmessageAddress?
+    protected fun receive(objectMessage: ObjectMessage, pubkey: Pubkey) {
         try {
             if (pubkey is V4Pubkey) {
-                address = ctx.addressRepository.findContact(pubkey.tag)
-                if (address != null) {
-                    pubkey.decrypt(address.publicDecryptionKey)
+                ctx.addressRepository.findContact(pubkey.tag)?.let {
+                    if (it.pubkey == null) {
+                        pubkey.decrypt(it.publicDecryptionKey)
+                        updatePubkey(it, pubkey)
+                    }
                 }
             } else {
-                address = ctx.addressRepository.findContact(pubkey.ripe)
+                ctx.addressRepository.findContact(pubkey.ripe)?.let {
+                    if (it.pubkey == null) {
+                        updatePubkey(it, pubkey)
+                    }
+                }
             }
-            if (address != null && address.pubkey == null) {
-                updatePubkey(address, pubkey)
-            }
-        } catch (_: DecryptionFailedException) {}
+        } catch (_: DecryptionFailedException) {
+        }
 
     }
 
@@ -101,19 +105,20 @@ internal open class DefaultMessageListener(
         }
     }
 
-    protected fun receive(`object`: ObjectMessage, msg: Msg) {
+    protected fun receive(objectMessage: ObjectMessage, msg: Msg) {
         for (identity in ctx.addressRepository.getIdentities()) {
             try {
                 msg.decrypt(identity.privateKey!!.privateEncryptionKey)
                 val plaintext = msg.plaintext!!
                 plaintext.to = identity
-                if (!`object`.isSignatureValid(plaintext.from.pubkey!!)) {
-                    LOG.warn("Msg with IV " + `object`.inventoryVector + " was successfully decrypted, but signature check failed. Ignoring.")
+                if (!objectMessage.isSignatureValid(plaintext.from.pubkey!!)) {
+                    LOG.warn("Msg with IV " + objectMessage.inventoryVector + " was successfully decrypted, but signature check failed. Ignoring.")
                 } else {
-                    receive(`object`.inventoryVector, plaintext)
+                    receive(objectMessage.inventoryVector, plaintext)
                 }
                 break
-            } catch (_: DecryptionFailedException) {}
+            } catch (_: DecryptionFailedException) {
+            }
         }
     }
 
@@ -122,11 +127,11 @@ internal open class DefaultMessageListener(
             ctx.messageRepository.getMessageForAck(ack.data)?.let {
                 ctx.labeler.markAsAcknowledged(it)
                 ctx.messageRepository.save(it)
-            }
+            } ?: LOG.debug("Message not found for ack ${hex(ack.data)}")
         }
     }
 
-    protected fun receive(`object`: ObjectMessage, broadcast: Broadcast) {
+    protected fun receive(objectMessage: ObjectMessage, broadcast: Broadcast) {
         val tag = if (broadcast is V5Broadcast) broadcast.tag else null
         for (subscription in ctx.addressRepository.getSubscriptions(broadcast.version)) {
             if (tag != null && !Arrays.equals(tag, subscription.tag)) {
@@ -134,12 +139,13 @@ internal open class DefaultMessageListener(
             }
             try {
                 broadcast.decrypt(subscription.publicDecryptionKey)
-                if (!`object`.isSignatureValid(broadcast.plaintext!!.from.pubkey!!)) {
-                    LOG.warn("Broadcast with IV " + `object`.inventoryVector + " was successfully decrypted, but signature check failed. Ignoring.")
+                if (!objectMessage.isSignatureValid(broadcast.plaintext!!.from.pubkey!!)) {
+                    LOG.warn("Broadcast with IV " + objectMessage.inventoryVector + " was successfully decrypted, but signature check failed. Ignoring.")
                 } else {
-                    receive(`object`.inventoryVector, broadcast.plaintext!!)
+                    receive(objectMessage.inventoryVector, broadcast.plaintext!!)
                 }
-            } catch (_: DecryptionFailedException) {}
+            } catch (_: DecryptionFailedException) {
+            }
         }
     }
 
@@ -158,7 +164,7 @@ internal open class DefaultMessageListener(
             msg.ackMessage?.let {
                 ctx.inventory.storeObject(it)
                 ctx.networkHandler.offer(it.inventoryVector)
-            }
+            } ?: LOG.debug("ack message expected")
         }
     }
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/InternalContext.kt b/core/src/main/java/ch/dissem/bitmessage/InternalContext.kt
index e36a8ac..62bba56 100644
--- a/core/src/main/java/ch/dissem/bitmessage/InternalContext.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/InternalContext.kt
@@ -28,7 +28,6 @@ import ch.dissem.bitmessage.utils.UnixTime
 import org.slf4j.LoggerFactory
 import java.util.*
 import java.util.concurrent.Executors
-import kotlin.properties.Delegates
 import kotlin.reflect.KProperty
 
 /**
@@ -68,7 +67,8 @@ class InternalContext(
         get() = _streams.toLongArray()
 
     init {
-        instance = this
+        lateinit.instance = this
+        lateinit = ContextDelegate()
         Singleton.initialize(cryptography)
 
         // TODO: streams of new identities and subscriptions should also be added. This works only after a restart.
@@ -102,24 +102,24 @@ class InternalContext(
         val recipient = to ?: from
         val expires = UnixTime.now + timeToLive
         LOG.info("Expires at " + expires)
-        val `object` = ObjectMessage(
+        val objectMessage = ObjectMessage(
             stream = recipient.stream,
             expiresTime = expires,
             payload = payload
         )
-        if (`object`.isSigned) {
-            `object`.sign(
+        if (objectMessage.isSigned) {
+            objectMessage.sign(
                 from.privateKey ?: throw IllegalArgumentException("The given sending address is no identity")
             )
         }
         if (payload is Broadcast) {
             payload.encrypt()
         } else if (payload is Encrypted) {
-            `object`.encrypt(
+            objectMessage.encrypt(
                 recipient.pubkey ?: throw IllegalArgumentException("The public key for the recipient isn't available")
             )
         }
-        proofOfWorkService.doProofOfWork(to, `object`)
+        proofOfWorkService.doProofOfWork(to, objectMessage)
     }
 
     fun sendPubkey(identity: BitmessageAddress, targetStream: Long) {
@@ -163,12 +163,11 @@ class InternalContext(
             }
 
             val expires = UnixTime.now + TTL.getpubkey
-            LOG.info("Expires at " + expires)
-            val payload = GetPubkey(contact)
+            LOG.info("Expires at $expires")
             val request = ObjectMessage(
                 stream = contact.stream,
                 expiresTime = expires,
-                payload = payload
+                payload = GetPubkey(contact)
             )
             proofOfWorkService.doProofOfWork(request)
         }
@@ -179,14 +178,14 @@ class InternalContext(
             address.alias = it.alias
             address.isSubscribed = it.isSubscribed
         }
-        for (`object` in inventory.getObjects(address.stream, address.version, ObjectType.PUBKEY)) {
+        for (objectMessage in inventory.getObjects(address.stream, address.version, ObjectType.PUBKEY)) {
             try {
-                val pubkey = `object`.payload as Pubkey
+                val pubkey = objectMessage.payload as Pubkey
                 if (address.version == 4L) {
                     val v4Pubkey = pubkey as V4Pubkey
                     if (Arrays.equals(address.tag, v4Pubkey.tag)) {
                         v4Pubkey.decrypt(address.publicDecryptionKey)
-                        if (`object`.isSignatureValid(v4Pubkey)) {
+                        if (objectMessage.isSignatureValid(v4Pubkey)) {
                             address.pubkey = v4Pubkey
                             addressRepository.save(address)
                             break
@@ -219,17 +218,19 @@ class InternalContext(
         fun setContext(context: InternalContext)
     }
 
+    class ContextDelegate {
+        internal lateinit var instance: InternalContext
+        operator fun getValue(thisRef: Any?, property: KProperty<*>) = instance
+        operator fun setValue(thisRef: Any?, property: KProperty<*>, value: InternalContext) {}
+    }
+
     companion object {
         private val LOG = LoggerFactory.getLogger(InternalContext::class.java)
 
         @JvmField val NETWORK_NONCE_TRIALS_PER_BYTE: Long = 1000
         @JvmField val NETWORK_EXTRA_BYTES: Long = 1000
 
-        private var instance: InternalContext by Delegates.notNull<InternalContext>()
-
-        operator fun getValue(thisRef: Any?, property: KProperty<*>) = instance
-        operator fun setValue(thisRef: Any?, property: KProperty<*>, value: InternalContext) {
-            instance = value
-        }
+        var lateinit = ContextDelegate()
+            private set
     }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.kt b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.kt
index 2472d67..67d6637 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.kt
@@ -22,6 +22,7 @@ import ch.dissem.bitmessage.entity.*
 import ch.dissem.bitmessage.entity.payload.Msg
 import ch.dissem.bitmessage.ports.ProofOfWorkEngine
 import ch.dissem.bitmessage.ports.ProofOfWorkRepository.Item
+import ch.dissem.bitmessage.utils.Strings
 import org.slf4j.LoggerFactory
 import java.io.IOException
 import java.util.*
@@ -31,7 +32,7 @@ import java.util.*
  */
 class ProofOfWorkService : ProofOfWorkEngine.Callback {
 
-    private val ctx by InternalContext
+    private val ctx by InternalContext.lateinit
     private val cryptography by lazy { ctx.cryptography }
     private val powRepo by lazy { ctx.proofOfWorkRepository }
     private val messageRepo by lazy { ctx.messageRepository }
@@ -45,75 +46,69 @@ class ProofOfWorkService : ProofOfWorkEngine.Callback {
             override fun run() {
                 LOG.info("Doing POW for " + items.size + " tasks.")
                 for (initialHash in items) {
-                    val (`object`, nonceTrialsPerByte, extraBytes) = powRepo.getItem(initialHash)
-                    cryptography.doProofOfWork(`object`, nonceTrialsPerByte, extraBytes,
+                    val (objectMessage, nonceTrialsPerByte, extraBytes) = powRepo.getItem(initialHash)
+                    cryptography.doProofOfWork(objectMessage, nonceTrialsPerByte, extraBytes,
                         this@ProofOfWorkService)
                 }
             }
         }, delayInMilliseconds)
     }
 
-    fun doProofOfWork(`object`: ObjectMessage) {
-        doProofOfWork(null, `object`)
+    fun doProofOfWork(objectMessage: ObjectMessage) {
+        doProofOfWork(null, objectMessage)
     }
 
-    fun doProofOfWork(recipient: BitmessageAddress?, `object`: ObjectMessage) {
+    fun doProofOfWork(recipient: BitmessageAddress?, objectMessage: ObjectMessage) {
         val pubkey = recipient?.pubkey
 
         val nonceTrialsPerByte = pubkey?.nonceTrialsPerByte ?: NETWORK_NONCE_TRIALS_PER_BYTE
         val extraBytes = pubkey?.extraBytes ?: NETWORK_EXTRA_BYTES
 
-        powRepo.putObject(`object`, nonceTrialsPerByte, extraBytes)
-        if (`object`.payload is PlaintextHolder) {
-            `object`.payload.plaintext?.let {
-                it.initialHash = cryptography.getInitialHash(`object`)
+        powRepo.putObject(objectMessage, nonceTrialsPerByte, extraBytes)
+        if (objectMessage.payload is PlaintextHolder) {
+            objectMessage.payload.plaintext?.let {
+                it.initialHash = cryptography.getInitialHash(objectMessage)
                 messageRepo.save(it)
-            }
+            } ?: LOG.error("PlaintextHolder without Plaintext shouldn't make it to the POW")
         }
-        cryptography.doProofOfWork(`object`, nonceTrialsPerByte, extraBytes, this)
+        cryptography.doProofOfWork(objectMessage, nonceTrialsPerByte, extraBytes, this)
     }
 
     fun doProofOfWorkWithAck(plaintext: Plaintext, expirationTime: Long) {
-        val ack = plaintext.ackMessage
+        val ack = plaintext.ackMessage!!
         messageRepo.save(plaintext)
-        val item = Item(ack!!, NETWORK_NONCE_TRIALS_PER_BYTE, NETWORK_EXTRA_BYTES,
+        val item = 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 fun onNonceCalculated(initialHash: ByteArray, nonce: ByteArray) {
-        val (`object`, _, _, expirationTime, message) = powRepo.getItem(initialHash)
+        val (objectMessage, _, _, expirationTime, message) = powRepo.getItem(initialHash)
         if (message == null) {
-            `object`.nonce = nonce
+            objectMessage.nonce = nonce
             messageRepo.getMessage(initialHash)?.let {
-                it.inventoryVector = `object`.inventoryVector
+                it.inventoryVector = objectMessage.inventoryVector
                 it.updateNextTry()
                 ctx.labeler.markAsSent(it)
                 messageRepo.save(it)
             }
-            try {
-                ctx.networkListener.receive(`object`)
-            } catch (e: IOException) {
-                LOG.debug(e.message, e)
-            }
-
-            ctx.inventory.storeObject(`object`)
-            ctx.networkHandler.offer(`object`.inventoryVector)
+            ctx.inventory.storeObject(objectMessage)
+            ctx.networkHandler.offer(objectMessage.inventoryVector)
         } else {
             message.ackMessage!!.nonce = nonce
-            val `object` = ObjectMessage.Builder()
+            val newObjectMessage = ObjectMessage.Builder()
                 .stream(message.stream)
                 .expiresTime(expirationTime!!)
                 .payload(Msg(message))
                 .build()
-            if (`object`.isSigned) {
-                `object`.sign(message.from.privateKey!!)
+            if (newObjectMessage.isSigned) {
+                newObjectMessage.sign(message.from.privateKey!!)
             }
-            if (`object`.payload is Encrypted) {
-                `object`.encrypt(message.to!!.pubkey!!)
+            if (newObjectMessage.payload is Encrypted) {
+                newObjectMessage.encrypt(message.to!!.pubkey!!)
             }
-            doProofOfWork(message.to, `object`)
+            doProofOfWork(message.to, newObjectMessage)
         }
         powRepo.removeObject(initialHash)
     }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Addr.kt b/core/src/main/java/ch/dissem/bitmessage/entity/Addr.kt
index 0e7e8f6..056dd63 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Addr.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Addr.kt
@@ -28,14 +28,14 @@ data class Addr constructor(val addresses: List<NetworkAddress>) : MessagePayloa
     override val command: MessagePayload.Command = MessagePayload.Command.ADDR
 
     override fun write(out: OutputStream) {
-        Encode.varInt(addresses.size.toLong(), out)
+        Encode.varInt(addresses.size, out)
         for (address in addresses) {
             address.write(out)
         }
     }
 
     override fun write(buffer: ByteBuffer) {
-        Encode.varInt(addresses.size.toLong(), buffer)
+        Encode.varInt(addresses.size, buffer)
         for (address in addresses) {
             address.write(buffer)
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/GetData.kt b/core/src/main/java/ch/dissem/bitmessage/entity/GetData.kt
index 62fab2b..feebea1 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/GetData.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/GetData.kt
@@ -29,14 +29,14 @@ class GetData constructor(var inventory: List<InventoryVector>) : MessagePayload
     override val command: MessagePayload.Command = MessagePayload.Command.GETDATA
 
     override fun write(out: OutputStream) {
-        Encode.varInt(inventory.size.toLong(), out)
+        Encode.varInt(inventory.size, out)
         for (iv in inventory) {
             iv.write(out)
         }
     }
 
     override fun write(buffer: ByteBuffer) {
-        Encode.varInt(inventory.size.toLong(), buffer)
+        Encode.varInt(inventory.size, buffer)
         for (iv in inventory) {
             iv.write(buffer)
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Inv.kt b/core/src/main/java/ch/dissem/bitmessage/entity/Inv.kt
index 42f963f..b0c5af9 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Inv.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Inv.kt
@@ -29,14 +29,14 @@ class Inv constructor(val inventory: List<InventoryVector>) : MessagePayload {
     override val command: MessagePayload.Command = MessagePayload.Command.INV
 
     override fun write(out: OutputStream) {
-        Encode.varInt(inventory.size.toLong(), out)
+        Encode.varInt(inventory.size, out)
         for (iv in inventory) {
             iv.write(out)
         }
     }
 
     override fun write(buffer: ByteBuffer) {
-        Encode.varInt(inventory.size.toLong(), buffer)
+        Encode.varInt(inventory.size, buffer)
         for (iv in inventory) {
             iv.write(buffer)
         }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.kt b/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.kt
index 3b5369e..d0c427a 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.kt
@@ -43,7 +43,7 @@ data class NetworkMessage(
     @Throws(IOException::class)
     override fun write(out: OutputStream) {
         // magic
-        Encode.int32(MAGIC.toLong(), out)
+        Encode.int32(MAGIC, out)
 
         // ASCII string identifying the packet content, NULL padded (non-NULL padding results in packet rejected)
         val command = payload.command.name.toLowerCase()
@@ -57,7 +57,7 @@ data class NetworkMessage(
         // Length of payload in number of bytes. Because of other restrictions, there is no reason why this length would
         // ever be larger than 1600003 bytes. Some clients include a sanity-check to avoid processing messages which are
         // larger than this.
-        Encode.int32(payloadBytes.size.toLong(), out)
+        Encode.int32(payloadBytes.size, out)
 
         // checksum
         out.write(getChecksum(payloadBytes))
@@ -92,7 +92,7 @@ data class NetworkMessage(
 
     private fun writeHeader(out: ByteBuffer): ByteArray {
         // magic
-        Encode.int32(MAGIC.toLong(), out)
+        Encode.int32(MAGIC, out)
 
         // ASCII string identifying the packet content, NULL padded (non-NULL padding results in packet rejected)
         val command = payload.command.name.toLowerCase()
@@ -107,7 +107,7 @@ data class NetworkMessage(
         // Length of payload in number of bytes. Because of other restrictions, there is no reason why this length would
         // ever be larger than 1600003 bytes. Some clients include a sanity-check to avoid processing messages which are
         // larger than this.
-        Encode.int32(payloadBytes.size.toLong(), out)
+        Encode.int32(payloadBytes.size, out)
 
         // checksum
         out.put(getChecksum(payloadBytes))
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.kt b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.kt
index fc4ee0a..462ae83 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Plaintext.kt
@@ -17,6 +17,7 @@
 package ch.dissem.bitmessage.entity
 
 import ch.dissem.bitmessage.entity.Plaintext.Encoding.*
+import ch.dissem.bitmessage.entity.Plaintext.Type.MSG
 import ch.dissem.bitmessage.entity.payload.Msg
 import ch.dissem.bitmessage.entity.payload.Pubkey.Feature
 import ch.dissem.bitmessage.entity.valueobject.ExtendedEncoding
@@ -38,10 +39,20 @@ import kotlin.collections.HashSet
 fun message(encoding: Plaintext.Encoding, subject: String, body: String): ByteArray = when (encoding) {
     SIMPLE -> "Subject:$subject\nBody:$body".toByteArray()
     EXTENDED -> Message.Builder().subject(subject).body(body).build().zip()
-    TRIVIAL -> (subject+body).toByteArray()
+    TRIVIAL -> (subject + body).toByteArray()
     IGNORE -> ByteArray(0)
 }
 
+fun ackData(type: Plaintext.Type, ackData: ByteArray?): ByteArray? {
+    if (ackData != null) {
+        return ackData
+    } else if (type == MSG) {
+        return cryptography().randomBytes(Msg.ACK_LENGTH)
+    } else {
+        return null
+    }
+}
+
 /**
  * The unencrypted message to be sent by 'msg' or 'broadcast'.
  */
@@ -52,7 +63,7 @@ class Plaintext private constructor(
     val encodingCode: Long,
     val message: ByteArray,
     val ackData: ByteArray?,
-    ackMessage: Lazy<ObjectMessage?>,
+    ackMessage: Lazy<ObjectMessage?> = lazy { Factory.createAck(from, ackData, ttl) },
     val conversationId: UUID = UUID.randomUUID(),
     var inventoryVector: InventoryVector? = null,
     var signature: ByteArray? = null,
@@ -121,7 +132,7 @@ class Plaintext private constructor(
         to: BitmessageAddress?,
         encoding: Encoding,
         message: ByteArray,
-        ackData: ByteArray = cryptography().randomBytes(Msg.ACK_LENGTH),
+        ackData: ByteArray? = null,
         conversationId: UUID = UUID.randomUUID(),
         inventoryVector: InventoryVector? = null,
         signature: ByteArray? = null,
@@ -131,21 +142,20 @@ class Plaintext private constructor(
         labels: MutableSet<Label> = HashSet(),
         status: Status
     ) : this(
-        type,
-        from,
-        to,
-        encoding.code,
-        message,
-        ackData,
-        lazy { Factory.createAck(from, ackData, ttl) },
-        conversationId,
-        inventoryVector,
-        signature,
-        received,
-        initialHash,
-        ttl,
-        labels,
-        status
+        type = type,
+        from = from,
+        to = to,
+        encoding = encoding.code,
+        message = message,
+        ackMessage = ackData(type, ackData),
+        conversationId = conversationId,
+        inventoryVector = inventoryVector,
+        signature = signature,
+        received = received,
+        initialHash = initialHash,
+        ttl = ttl,
+        labels = labels,
+        status = status
     )
 
     constructor(
@@ -164,13 +174,13 @@ class Plaintext private constructor(
         labels: MutableSet<Label> = HashSet(),
         status: Status
     ) : this(
-        type,
-        from,
-        to,
-        encoding,
-        message,
-        null,
-        lazy {
+        type = type,
+        from = from,
+        to = to,
+        encodingCode = encoding,
+        message = message,
+        ackData = null,
+        ackMessage = lazy {
             if (ackMessage != null && ackMessage.isNotEmpty()) {
                 Factory.getObjectMessage(
                     3,
@@ -178,14 +188,14 @@ class Plaintext private constructor(
                     ackMessage.size)
             } else null
         },
-        conversationId,
-        inventoryVector,
-        signature,
-        received,
-        initialHash,
-        ttl,
-        labels,
-        status
+        conversationId = conversationId,
+        inventoryVector = inventoryVector,
+        signature = signature,
+        received = received,
+        initialHash = initialHash,
+        ttl = ttl,
+        labels = labels,
+        status = status
     )
 
     constructor(
@@ -195,37 +205,36 @@ class Plaintext private constructor(
         encoding: Encoding = SIMPLE,
         subject: String,
         body: String,
-        ackData: ByteArray = cryptography().randomBytes(Msg.ACK_LENGTH),
+        ackData: ByteArray? = null,
         conversationId: UUID = UUID.randomUUID(),
         ttl: Long = TTL.msg,
         labels: MutableSet<Label> = HashSet(),
         status: Status = Status.DRAFT
     ) : this(
-        type,
-        from,
-        to,
-        encoding.code,
-        message(encoding, subject, body),
-        ackData,
-        lazy { Factory.createAck(from, ackData, ttl) },
-        conversationId,
-        null,
-        null,
-        null,
-        null,
-        ttl,
-        labels,
-        status
+        type = type,
+        from = from,
+        to = to,
+        encoding = encoding.code,
+        message = message(encoding, subject, body),
+        ackMessage = ackData(type, ackData),
+        conversationId = conversationId,
+        inventoryVector = null,
+        signature = null,
+        received = null,
+        initialHash = null,
+        ttl = ttl,
+        labels = labels,
+        status = status
     )
 
     constructor(builder: Builder) : this(
-        builder.type,
-        builder.from ?: throw IllegalStateException("sender identity not set"),
-        builder.to,
-        builder.encoding,
-        builder.message,
-        builder.ackData,
-        lazy {
+        type = builder.type,
+        from = builder.from ?: throw IllegalStateException("sender identity not set"),
+        to = builder.to,
+        encodingCode = builder.encoding,
+        message = builder.message,
+        ackData = builder.ackData,
+        ackMessage = lazy {
             val ackMsg = builder.ackMessage
             if (ackMsg != null && ackMsg.isNotEmpty()) {
                 Factory.getObjectMessage(
@@ -236,15 +245,17 @@ class Plaintext private constructor(
                 Factory.createAck(builder.from!!, builder.ackData, builder.ttl)
             }
         },
-        builder.conversation ?: UUID.randomUUID(),
-        builder.inventoryVector,
-        builder.signature,
-        builder.received,
-        null,
-        builder.ttl,
-        builder.labels,
-        builder.status ?: Status.RECEIVED
-    )
+        conversationId = builder.conversation ?: UUID.randomUUID(),
+        inventoryVector = builder.inventoryVector,
+        signature = builder.signature,
+        received = builder.received,
+        initialHash = null,
+        ttl = builder.ttl,
+        labels = builder.labels,
+        status = builder.status ?: Status.RECEIVED
+    ) {
+        id = builder.id
+    }
 
     fun write(out: OutputStream, includeSignature: Boolean) {
         Encode.varInt(from.version, out)
@@ -259,7 +270,7 @@ class Plaintext private constructor(
                 Encode.varInt(0, out)
             }
         } else {
-            Encode.int32(from.pubkey!!.behaviorBitfield.toLong(), out)
+            Encode.int32(from.pubkey!!.behaviorBitfield, out)
             out.write(from.pubkey!!.signingKey, 1, 64)
             out.write(from.pubkey!!.encryptionKey, 1, 64)
             if (from.version >= 3) {
@@ -267,13 +278,13 @@ class Plaintext private constructor(
                 Encode.varInt(from.pubkey!!.extraBytes, out)
             }
         }
-        if (type == Type.MSG) {
+        if (type == MSG) {
             out.write(to!!.ripe)
         }
         Encode.varInt(encodingCode, out)
-        Encode.varInt(message.size.toLong(), out)
+        Encode.varInt(message.size, out)
         out.write(message)
-        if (type == Type.MSG) {
+        if (type == MSG) {
             if (to?.has(Feature.DOES_ACK) ?: false) {
                 val ack = ByteArrayOutputStream()
                 ackMessage?.write(ack)
@@ -286,8 +297,7 @@ class Plaintext private constructor(
             if (signature == null) {
                 Encode.varInt(0, out)
             } else {
-                Encode.varInt(signature!!.size.toLong(), out)
-                out.write(signature!!)
+                Encode.varBytes(signature!!, out)
             }
         }
     }
@@ -305,7 +315,7 @@ class Plaintext private constructor(
                 Encode.varInt(0, buffer)
             }
         } else {
-            Encode.int32(from.pubkey!!.behaviorBitfield.toLong(), buffer)
+            Encode.int32(from.pubkey!!.behaviorBitfield, buffer)
             buffer.put(from.pubkey!!.signingKey, 1, 64)
             buffer.put(from.pubkey!!.encryptionKey, 1, 64)
             if (from.version >= 3) {
@@ -313,13 +323,12 @@ class Plaintext private constructor(
                 Encode.varInt(from.pubkey!!.extraBytes, buffer)
             }
         }
-        if (type == Type.MSG) {
+        if (type == MSG) {
             buffer.put(to!!.ripe)
         }
         Encode.varInt(encodingCode, buffer)
-        Encode.varInt(message.size.toLong(), buffer)
-        buffer.put(message)
-        if (type == Type.MSG) {
+        Encode.varBytes(message, buffer)
+        if (type == MSG) {
             if (to!!.has(Feature.DOES_ACK) && ackMessage != null) {
                 Encode.varBytes(Encode.bytes(ackMessage!!), buffer)
             } else {
@@ -331,8 +340,7 @@ class Plaintext private constructor(
             if (sig == null) {
                 Encode.varInt(0, buffer)
             } else {
-                Encode.varInt(sig.size.toLong(), buffer)
-                buffer.put(sig)
+                Encode.varBytes(sig, buffer)
             }
         }
     }
@@ -365,7 +373,7 @@ class Plaintext private constructor(
             val firstLine = s.nextLine()
             if (encodingCode == EXTENDED.code) {
                 if (Message.TYPE == extendedData?.type) {
-                    return (extendedData!!.content as Message?)?.subject
+                    return (extendedData!!.content as? Message)?.subject
                 } else {
                     return null
                 }
@@ -551,10 +559,12 @@ class Plaintext private constructor(
             return this
         }
 
-        fun to(address: BitmessageAddress): Builder {
-            if (type != Type.MSG && to != null)
-                throw IllegalArgumentException("recipient address only allowed for msg")
-            to = address
+        fun to(address: BitmessageAddress?): Builder {
+            if (address != null) {
+                if (type != MSG && to != null)
+                    throw IllegalArgumentException("recipient address only allowed for msg")
+                to = address
+            }
             return this
         }
 
@@ -594,7 +604,7 @@ class Plaintext private constructor(
         }
 
         fun destinationRipe(ripe: ByteArray?): Builder {
-            if (type != Type.MSG && ripe != null) throw IllegalArgumentException("ripe only allowed for msg")
+            if (type != MSG && ripe != null) throw IllegalArgumentException("ripe only allowed for msg")
             this.destinationRipe = ripe
             return this
         }
@@ -622,7 +632,6 @@ class Plaintext private constructor(
             } catch (e: UnsupportedEncodingException) {
                 throw ApplicationException(e)
             }
-
             return this
         }
 
@@ -632,13 +641,13 @@ class Plaintext private constructor(
         }
 
         fun ackMessage(ack: ByteArray?): Builder {
-            if (type != Type.MSG && ack != null) throw IllegalArgumentException("ackMessage only allowed for msg")
+            if (type != MSG && ack != null) throw IllegalArgumentException("ackMessage only allowed for msg")
             this.ackMessage = ack
             return this
         }
 
         fun ackData(ackData: ByteArray?): Builder {
-            if (type != Type.MSG && ackData != null)
+            if (type != MSG && ackData != null)
                 throw IllegalArgumentException("ackMessage only allowed for msg")
             this.ackData = ackData
             return this
@@ -704,7 +713,7 @@ class Plaintext private constructor(
             if (to == null && type != Type.BROADCAST && destinationRipe != null) {
                 to = BitmessageAddress(0, 0, destinationRipe!!)
             }
-            if (type == Type.MSG && ackMessage == null && ackData == null) {
+            if (type == MSG && ackMessage == null && ackData == null) {
                 ackData = cryptography().randomBytes(Msg.ACK_LENGTH)
             }
             if (ttl <= 0) {
@@ -733,10 +742,10 @@ class Plaintext private constructor(
                 .publicEncryptionKey(Decode.bytes(`in`, 64))
                 .nonceTrialsPerByte(if (version >= 3) Decode.varInt(`in`) else 0)
                 .extraBytes(if (version >= 3) Decode.varInt(`in`) else 0)
-                .destinationRipe(if (type == Type.MSG) Decode.bytes(`in`, 20) else null)
+                .destinationRipe(if (type == MSG) Decode.bytes(`in`, 20) else null)
                 .encoding(Decode.varInt(`in`))
                 .message(Decode.varBytes(`in`))
-                .ackMessage(if (type == Type.MSG) Decode.varBytes(`in`) else null)
+                .ackMessage(if (type == MSG) Decode.varBytes(`in`) else null)
         }
     }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/Version.kt b/core/src/main/java/ch/dissem/bitmessage/entity/Version.kt
index 3a1c3f7..07d6d47 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/Version.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/Version.kt
@@ -78,7 +78,7 @@ class Version constructor(
     override val command: MessagePayload.Command = MessagePayload.Command.VERSION
 
     override fun write(out: OutputStream) {
-        Encode.int32(version.toLong(), out)
+        Encode.int32(version, out)
         Encode.int64(services, out)
         Encode.int64(timestamp, out)
         addrRecv.write(out, true)
@@ -89,7 +89,7 @@ class Version constructor(
     }
 
     override fun write(buffer: ByteBuffer) {
-        Encode.int32(version.toLong(), buffer)
+        Encode.int32(version, buffer)
         Encode.int64(services, buffer)
         Encode.int64(timestamp, buffer)
         addrRecv.write(buffer, true)
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.kt b/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.kt
index 15f8bef..d6df388 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/CryptoBox.kt
@@ -114,7 +114,7 @@ class CryptoBox : Streamable {
 
     private fun writeWithoutMAC(out: OutputStream) {
         out.write(initializationVector)
-        Encode.int16(curveType.toLong(), out)
+        Encode.int16(curveType, out)
         writeCoordinateComponent(out, Points.getX(R))
         writeCoordinateComponent(out, Points.getY(R))
         out.write(encrypted)
@@ -123,14 +123,14 @@ class CryptoBox : Streamable {
     private fun writeCoordinateComponent(out: OutputStream, x: ByteArray) {
         val offset = Bytes.numberOfLeadingZeros(x)
         val length = x.size - offset
-        Encode.int16(length.toLong(), out)
+        Encode.int16(length, out)
         out.write(x, offset, length)
     }
 
     private fun writeCoordinateComponent(buffer: ByteBuffer, x: ByteArray) {
         val offset = Bytes.numberOfLeadingZeros(x)
         val length = x.size - offset
-        Encode.int16(length.toLong(), buffer)
+        Encode.int16(length, buffer)
         buffer.put(x, offset, length)
     }
 
@@ -141,7 +141,7 @@ class CryptoBox : Streamable {
 
     override fun write(buffer: ByteBuffer) {
         buffer.put(initializationVector)
-        Encode.int16(curveType.toLong(), buffer)
+        Encode.int16(curveType, buffer)
         writeCoordinateComponent(buffer, Points.getX(R))
         writeCoordinateComponent(buffer, Points.getY(R))
         buffer.put(encrypted)
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/payload/V2Pubkey.kt b/core/src/main/java/ch/dissem/bitmessage/entity/payload/V2Pubkey.kt
index f599153..28acf6f 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/payload/V2Pubkey.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/payload/V2Pubkey.kt
@@ -31,13 +31,13 @@ open class V2Pubkey constructor(version: Long, override val stream: Long, overri
     override val encryptionKey: ByteArray = if (encryptionKey.size == 64) add0x04(encryptionKey) else encryptionKey
 
     override fun write(out: OutputStream) {
-        Encode.int32(behaviorBitfield.toLong(), out)
+        Encode.int32(behaviorBitfield, out)
         out.write(signingKey, 1, 64)
         out.write(encryptionKey, 1, 64)
     }
 
     override fun write(buffer: ByteBuffer) {
-        Encode.int32(behaviorBitfield.toLong(), buffer)
+        Encode.int32(behaviorBitfield, buffer)
         buffer.put(signingKey, 1, 64)
         buffer.put(encryptionKey, 1, 64)
     }
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.kt b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.kt
index 378aa35..7b221df 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/Label.kt
@@ -19,11 +19,14 @@ package ch.dissem.bitmessage.entity.valueobject
 import java.io.Serializable
 import java.util.*
 
-data class Label(private val label: String, val type: Label.Type,
-                 /**
-                  * RGBA representation for the color.
-                  */
-                 var color: Int) : Serializable {
+data class Label(
+    private val label: String,
+    val type: Label.Type?,
+    /**
+     * RGBA representation for the color.
+     */
+    var color: Int
+) : Serializable {
 
     var id: Any? = null
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/NetworkAddress.kt b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/NetworkAddress.kt
index e332a04..01be7f6 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/NetworkAddress.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/NetworkAddress.kt
@@ -30,7 +30,7 @@ import java.util.*
 /**
  * A node's address. It's written in IPv6 format.
  */
-data class NetworkAddress constructor(
+data class NetworkAddress(
     var time: Long,
 
     /**
@@ -47,25 +47,25 @@ data class NetworkAddress constructor(
      * IPv6 address. IPv4 addresses are written into the message as a 16 byte IPv4-mapped IPv6 address
      * (12 bytes 00 00 00 00 00 00 00 00 00 00 FF FF, followed by the 4 bytes of the IPv4 address).
      */
-    val iPv6: ByteArray,
+    val IPv6: ByteArray,
     val port: Int
 ) : Streamable {
 
     fun provides(service: Version.Service?): Boolean = service?.isEnabled(services) ?: false
 
     fun toInetAddress(): InetAddress {
-        return InetAddress.getByAddress(iPv6)
+        return InetAddress.getByAddress(IPv6)
     }
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
         if (other !is NetworkAddress) return false
 
-        return port == other.port && Arrays.equals(iPv6, other.iPv6)
+        return port == other.port && Arrays.equals(IPv6, other.IPv6)
     }
 
     override fun hashCode(): Int {
-        var result = Arrays.hashCode(iPv6)
+        var result = Arrays.hashCode(IPv6)
         result = 31 * result + port
         return result
     }
@@ -84,8 +84,8 @@ data class NetworkAddress constructor(
             Encode.int32(stream, out)
         }
         Encode.int64(services, out)
-        out.write(iPv6)
-        Encode.int16(port.toLong(), out)
+        out.write(IPv6)
+        Encode.int16(port, out)
     }
 
     override fun write(buffer: ByteBuffer) {
@@ -98,8 +98,8 @@ data class NetworkAddress constructor(
             Encode.int32(stream, buffer)
         }
         Encode.int64(services, buffer)
-        buffer.put(iPv6)
-        Encode.int16(port.toLong(), buffer)
+        buffer.put(IPv6)
+        Encode.int16(port, buffer)
     }
 
     class Builder {
diff --git a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.kt b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.kt
index 1cfabda..cfc618a 100644
--- a/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/entity/valueobject/PrivateKey.kt
@@ -121,12 +121,10 @@ class PrivateKey : Streamable {
         Encode.varInt(pubkey.stream, out)
         val baos = ByteArrayOutputStream()
         pubkey.writeUnencrypted(baos)
-        Encode.varInt(baos.size().toLong(), out)
+        Encode.varInt(baos.size(), out)
         out.write(baos.toByteArray())
-        Encode.varInt(privateSigningKey.size.toLong(), out)
-        out.write(privateSigningKey)
-        Encode.varInt(privateEncryptionKey.size.toLong(), out)
-        out.write(privateEncryptionKey)
+        Encode.varBytes(privateSigningKey, out)
+        Encode.varBytes(privateEncryptionKey, out)
     }
 
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/AbstractCryptography.kt b/core/src/main/java/ch/dissem/bitmessage/ports/AbstractCryptography.kt
index 56b3522..e30f943 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/AbstractCryptography.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/AbstractCryptography.kt
@@ -37,7 +37,7 @@ import javax.crypto.spec.SecretKeySpec
  * Implements everything that isn't directly dependent on either Spongy- or Bouncycastle.
  */
 abstract class AbstractCryptography protected constructor(@JvmField protected val provider: Provider) : Cryptography {
-    private val context by InternalContext
+    private val context by InternalContext.lateinit
 
     @JvmField protected val ALGORITHM_ECDSA = "ECDSA"
     @JvmField protected val ALGORITHM_ECDSA_SHA1 = "SHA1withECDSA"
@@ -87,21 +87,21 @@ abstract class AbstractCryptography protected constructor(@JvmField protected va
         return result
     }
 
-    override fun doProofOfWork(`object`: ObjectMessage, nonceTrialsPerByte: Long,
+    override fun doProofOfWork(objectMessage: ObjectMessage, nonceTrialsPerByte: Long,
                                extraBytes: Long, callback: ProofOfWorkEngine.Callback) {
 
-        val initialHash = getInitialHash(`object`)
+        val initialHash = getInitialHash(objectMessage)
 
-        val target = getProofOfWorkTarget(`object`,
+        val target = getProofOfWorkTarget(objectMessage,
             max(nonceTrialsPerByte, NETWORK_NONCE_TRIALS_PER_BYTE), max(extraBytes, NETWORK_EXTRA_BYTES))
 
         context.proofOfWorkEngine.calculateNonce(initialHash, target, callback)
     }
 
     @Throws(InsufficientProofOfWorkException::class)
-    override fun checkProofOfWork(`object`: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long) {
-        val target = getProofOfWorkTarget(`object`, nonceTrialsPerByte, extraBytes)
-        val value = doubleSha512(`object`.nonce ?: throw ApplicationException("Object without nonce"), getInitialHash(`object`))
+    override fun checkProofOfWork(objectMessage: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long) {
+        val target = getProofOfWorkTarget(objectMessage, nonceTrialsPerByte, extraBytes)
+        val value = doubleSha512(objectMessage.nonce ?: throw ApplicationException("Object without nonce"), getInitialHash(objectMessage))
         if (Bytes.lt(target, value, 8)) {
             throw InsufficientProofOfWorkException(target, value)
         }
@@ -130,18 +130,18 @@ abstract class AbstractCryptography protected constructor(@JvmField protected va
         return false
     }
 
-    override fun getInitialHash(`object`: ObjectMessage): ByteArray {
-        return sha512(`object`.payloadBytesWithoutNonce)
+    override fun getInitialHash(objectMessage: ObjectMessage): ByteArray {
+        return sha512(objectMessage.payloadBytesWithoutNonce)
     }
 
-    override fun getProofOfWorkTarget(`object`: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long): ByteArray {
+    override fun getProofOfWorkTarget(objectMessage: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long): ByteArray {
         @Suppress("NAME_SHADOWING")
         val nonceTrialsPerByte = if (nonceTrialsPerByte == 0L) NETWORK_NONCE_TRIALS_PER_BYTE else nonceTrialsPerByte
         @Suppress("NAME_SHADOWING")
         val extraBytes = if (extraBytes == 0L) NETWORK_EXTRA_BYTES else extraBytes
 
-        val TTL = BigInteger.valueOf(`object`.expiresTime - UnixTime.now)
-        val powLength = BigInteger.valueOf(`object`.payloadBytesWithoutNonce.size + extraBytes)
+        val TTL = BigInteger.valueOf(objectMessage.expiresTime - UnixTime.now)
+        val powLength = BigInteger.valueOf(objectMessage.payloadBytesWithoutNonce.size + extraBytes)
         val denominator = BigInteger.valueOf(nonceTrialsPerByte)
             .multiply(
                 powLength.add(
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.kt b/core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.kt
index b7329eb..c951ad2 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/AbstractMessageRepository.kt
@@ -28,19 +28,19 @@ import ch.dissem.bitmessage.utils.UnixTime
 import java.util.*
 
 abstract class AbstractMessageRepository : MessageRepository {
-    protected var ctx by InternalContext
+    protected var ctx by InternalContext.lateinit
 
     protected fun saveContactIfNecessary(contact: BitmessageAddress?) {
         contact?.let {
-            val savedAddress = ctx.addressRepository.getAddress(contact.address)
+            val savedAddress = ctx.addressRepository.getAddress(it.address)
             if (savedAddress == null) {
-                ctx.addressRepository.save(contact)
-            } else if (savedAddress.pubkey == null && contact.pubkey != null) {
-                savedAddress.pubkey = contact.pubkey
-                ctx.addressRepository.save(savedAddress)
-            }
-            if (savedAddress != null) {
-                contact.alias = savedAddress.alias
+                ctx.addressRepository.save(it)
+            } else {
+                if (savedAddress.pubkey == null && it.pubkey != null) {
+                    savedAddress.pubkey = it.pubkey
+                    ctx.addressRepository.save(savedAddress)
+                }
+                it.alias = savedAddress.alias
             }
         }
     }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/Cryptography.kt b/core/src/main/java/ch/dissem/bitmessage/ports/Cryptography.kt
index 22176bb..32f7dee 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/Cryptography.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/Cryptography.kt
@@ -145,7 +145,7 @@ interface Cryptography {
      * Calculates the proof of work. This might take a long time, depending on the hardware, message size and time to
      * live.
 
-     * @param object             to do the proof of work for
+     * @param objectMessage      to do the proof of work for
      * *
      * @param nonceTrialsPerByte difficulty
      * *
@@ -153,11 +153,11 @@ interface Cryptography {
      * *
      * @param callback           to handle nonce once it's calculated
      */
-    fun doProofOfWork(`object`: ObjectMessage, nonceTrialsPerByte: Long,
+    fun doProofOfWork(objectMessage: ObjectMessage, nonceTrialsPerByte: Long,
                       extraBytes: Long, callback: ProofOfWorkEngine.Callback)
 
     /**
-     * @param object             to be checked
+     * @param objectMessage      to be checked
      * *
      * @param nonceTrialsPerByte difficulty
      * *
@@ -166,11 +166,11 @@ interface Cryptography {
      * @throws InsufficientProofOfWorkException if proof of work doesn't check out (makes it more difficult to send small messages)
      */
     @Throws(InsufficientProofOfWorkException::class)
-    fun checkProofOfWork(`object`: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long)
+    fun checkProofOfWork(objectMessage: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long)
 
-    fun getInitialHash(`object`: ObjectMessage): ByteArray
+    fun getInitialHash(objectMessage: ObjectMessage): ByteArray
 
-    fun getProofOfWorkTarget(`object`: ObjectMessage, nonceTrialsPerByte: Long = NETWORK_NONCE_TRIALS_PER_BYTE, extraBytes: Long = NETWORK_EXTRA_BYTES): ByteArray
+    fun getProofOfWorkTarget(objectMessage: ObjectMessage, nonceTrialsPerByte: Long = NETWORK_NONCE_TRIALS_PER_BYTE, extraBytes: Long = NETWORK_EXTRA_BYTES): ByteArray
 
     /**
      * Calculates the MAC for a message (data)
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.kt b/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.kt
index 43a4f6e..4df9048 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/DefaultLabeler.kt
@@ -23,7 +23,7 @@ import ch.dissem.bitmessage.entity.Plaintext.Type.BROADCAST
 import ch.dissem.bitmessage.entity.valueobject.Label
 
 open class DefaultLabeler : Labeler {
-    private var ctx by InternalContext
+    private var ctx by InternalContext.lateinit
 
     override fun setLabels(msg: Plaintext) {
         msg.status = RECEIVED
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/Inventory.kt b/core/src/main/java/ch/dissem/bitmessage/ports/Inventory.kt
index 2087354..9c4885d 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/Inventory.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/Inventory.kt
@@ -43,9 +43,9 @@ interface Inventory {
      */
     fun getObjects(stream: Long, version: Long, vararg types: ObjectType): List<ObjectMessage>
 
-    fun storeObject(`object`: ObjectMessage)
+    fun storeObject(objectMessage: ObjectMessage)
 
-    operator fun contains(`object`: ObjectMessage): Boolean
+    operator fun contains(objectMessage: ObjectMessage): Boolean
 
     /**
      * Deletes all objects that expired 5 minutes ago or earlier
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.kt b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.kt
index c1fd59a..51e0d02 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/MessageRepository.kt
@@ -28,7 +28,7 @@ interface MessageRepository {
 
     fun getLabels(vararg types: Label.Type): List<Label>
 
-    fun countUnread(label: Label): Int
+    fun countUnread(label: Label?): Int
 
     fun getMessage(id: Any): Plaintext
 
@@ -43,7 +43,7 @@ interface MessageRepository {
      * *
      * @return a distinct list of all conversations that have at least one message with the given label.
      */
-    fun findConversations(label: Label): List<UUID>
+    fun findConversations(label: Label?): List<UUID>
 
     fun findMessages(label: Label?): List<Plaintext>
 
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/NetworkHandler.kt b/core/src/main/java/ch/dissem/bitmessage/ports/NetworkHandler.kt
index 72fee7b..de7f24c 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/NetworkHandler.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/NetworkHandler.kt
@@ -81,6 +81,6 @@ interface NetworkHandler {
 
     interface MessageListener {
         @Throws(IOException::class)
-        fun receive(`object`: ObjectMessage)
+        fun receive(objectMessage: ObjectMessage)
     }
 }
diff --git a/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.kt b/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.kt
index fbf5f60..01693eb 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/ports/ProofOfWorkRepository.kt
@@ -29,14 +29,14 @@ interface ProofOfWorkRepository {
 
     fun getItems(): List<ByteArray>
 
-    fun putObject(`object`: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long)
+    fun putObject(objectMessage: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long)
 
     fun putObject(item: Item)
 
     fun removeObject(initialHash: ByteArray)
 
     data class Item @JvmOverloads constructor(
-        val `object`: ObjectMessage,
+        val objectMessage: ObjectMessage,
         val nonceTrialsPerByte: Long,
         val extraBytes: Long,
         // Needed for ACK POW calculation
diff --git a/core/src/main/java/ch/dissem/bitmessage/utils/ConversationService.kt b/core/src/main/java/ch/dissem/bitmessage/utils/ConversationService.kt
index 392a1cf..f06a6ed 100644
--- a/core/src/main/java/ch/dissem/bitmessage/utils/ConversationService.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/utils/ConversationService.kt
@@ -19,6 +19,7 @@ package ch.dissem.bitmessage.utils
 import ch.dissem.bitmessage.entity.Plaintext
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector
 import ch.dissem.bitmessage.ports.MessageRepository
+import org.slf4j.LoggerFactory
 import java.util.*
 import java.util.Collections
 import java.util.regex.Pattern
diff --git a/core/src/main/java/ch/dissem/bitmessage/utils/Encode.kt b/core/src/main/java/ch/dissem/bitmessage/utils/Encode.kt
index 1904c66..1b96935 100644
--- a/core/src/main/java/ch/dissem/bitmessage/utils/Encode.kt
+++ b/core/src/main/java/ch/dissem/bitmessage/utils/Encode.kt
@@ -27,19 +27,20 @@ import java.nio.ByteBuffer
  */
 object Encode {
     @JvmStatic fun varIntList(values: LongArray, stream: OutputStream) {
-        varInt(values.size.toLong(), stream)
+        varInt(values.size, stream)
         for (value in values) {
             varInt(value, stream)
         }
     }
 
     @JvmStatic fun varIntList(values: LongArray, buffer: ByteBuffer) {
-        varInt(values.size.toLong(), buffer)
+        varInt(values.size, buffer)
         for (value in values) {
             varInt(value, buffer)
         }
     }
 
+    @JvmStatic fun varInt(value: Int, buffer: ByteBuffer) = varInt(value.toLong(), buffer)
     @JvmStatic fun varInt(value: Long, buffer: ByteBuffer) {
         if (value < 0) {
             // This is due to the fact that Java doesn't really support unsigned values.
@@ -62,6 +63,7 @@ object Encode {
         }
     }
 
+    @JvmStatic fun varInt(value: Int) = varInt(value.toLong())
     @JvmStatic fun varInt(value: Long): ByteArray {
         val buffer = ByteBuffer.allocate(9)
         varInt(value, buffer)
@@ -69,6 +71,7 @@ object Encode {
         return Bytes.truncate(buffer.array(), buffer.limit())
     }
 
+    @JvmStatic @JvmOverloads fun varInt(value: Int, stream: OutputStream, counter: AccessCounter? = null) = varInt(value.toLong(), stream, counter)
     @JvmStatic @JvmOverloads fun varInt(value: Long, stream: OutputStream, counter: AccessCounter? = null) {
         val buffer = ByteBuffer.allocate(9)
         varInt(value, buffer)
@@ -77,27 +80,34 @@ object Encode {
         AccessCounter.inc(counter, buffer.limit())
     }
 
-    @JvmStatic @JvmOverloads fun int8(value: Long, stream: OutputStream, counter: AccessCounter? = null) {
-        stream.write(value.toInt())
+    @JvmStatic @JvmOverloads fun int8(value: Long, stream: OutputStream, counter: AccessCounter? = null) = int8(value.toInt(), stream, counter)
+    @JvmStatic @JvmOverloads fun int8(value: Int, stream: OutputStream, counter: AccessCounter? = null) {
+        stream.write(value)
         AccessCounter.inc(counter)
     }
 
-    @JvmStatic @JvmOverloads fun int16(value: Long, stream: OutputStream, counter: AccessCounter? = null) {
-        stream.write(ByteBuffer.allocate(2).putShort(value.toShort()).array())
+    @JvmStatic @JvmOverloads fun int16(value: Long, stream: OutputStream, counter: AccessCounter? = null) = int16(value.toShort(), stream, counter)
+    @JvmStatic @JvmOverloads fun int16(value: Int, stream: OutputStream, counter: AccessCounter? = null) = int16(value.toShort(), stream, counter)
+    @JvmStatic @JvmOverloads fun int16(value: Short, stream: OutputStream, counter: AccessCounter? = null) {
+        stream.write(ByteBuffer.allocate(2).putShort(value).array())
         AccessCounter.inc(counter, 2)
     }
 
-    @JvmStatic fun int16(value: Long, buffer: ByteBuffer) {
-        buffer.putShort(value.toShort())
+    @JvmStatic fun int16(value: Long, buffer: ByteBuffer) = int16(value.toShort(), buffer)
+    @JvmStatic fun int16(value: Int, buffer: ByteBuffer) = int16(value.toShort(), buffer)
+    @JvmStatic fun int16(value: Short, buffer: ByteBuffer) {
+        buffer.putShort(value)
     }
 
-    @JvmStatic @JvmOverloads fun int32(value: Long, stream: OutputStream, counter: AccessCounter? = null) {
-        stream.write(ByteBuffer.allocate(4).putInt(value.toInt()).array())
+    @JvmStatic @JvmOverloads fun int32(value: Long, stream: OutputStream, counter: AccessCounter? = null) = int32(value.toInt(), stream, counter)
+    @JvmStatic @JvmOverloads fun int32(value: Int, stream: OutputStream, counter: AccessCounter? = null) {
+        stream.write(ByteBuffer.allocate(4).putInt(value).array())
         AccessCounter.inc(counter, 4)
     }
 
-    @JvmStatic fun int32(value: Long, buffer: ByteBuffer) {
-        buffer.putInt(value.toInt())
+    @JvmStatic fun int32(value: Long, buffer: ByteBuffer) = int32(value.toInt(), buffer)
+    @JvmStatic fun int32(value: Int, buffer: ByteBuffer) {
+        buffer.putInt(value)
     }
 
     @JvmStatic @JvmOverloads fun int64(value: Long, stream: OutputStream, counter: AccessCounter? = null) {
diff --git a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.kt b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.kt
index b51cb7d..4814ac7 100644
--- a/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/BitmessageContextTest.kt
@@ -28,8 +28,8 @@ import ch.dissem.bitmessage.ports.DefaultLabeler
 import ch.dissem.bitmessage.ports.ProofOfWorkEngine
 import ch.dissem.bitmessage.ports.ProofOfWorkRepository
 import ch.dissem.bitmessage.testutils.TestInventory
-import ch.dissem.bitmessage.utils.Singleton
 import ch.dissem.bitmessage.utils.Singleton.cryptography
+import ch.dissem.bitmessage.utils.Strings.hex
 import ch.dissem.bitmessage.utils.TTL
 import ch.dissem.bitmessage.utils.TestUtils
 import ch.dissem.bitmessage.utils.UnixTime.MINUTE
@@ -40,12 +40,12 @@ import org.junit.Assert.*
 import org.junit.Before
 import org.junit.Test
 import java.util.*
+import kotlin.concurrent.thread
 
 /**
  * @author Christian Basler
  */
 class BitmessageContextTest {
-    private lateinit var ctx: BitmessageContext
     private var listener: BitmessageContext.Listener = mock()
     private val inventory = spy(TestInventory())
     private val testPowRepo = spy(object : ProofOfWorkRepository {
@@ -54,7 +54,7 @@ class BitmessageContextTest {
         internal var removed = 0
 
         override fun getItem(initialHash: ByteArray): ProofOfWorkRepository.Item {
-            return items[InventoryVector(initialHash)]!!
+            return items[InventoryVector(initialHash)] ?: throw IllegalArgumentException("${hex(initialHash)} not found in $items")
         }
 
         override fun getItems(): List<ByteArray> {
@@ -66,12 +66,12 @@ class BitmessageContextTest {
         }
 
         override fun putObject(item: ProofOfWorkRepository.Item) {
-            items.put(InventoryVector(cryptography().getInitialHash(item.`object`)), item)
+            items.put(InventoryVector(cryptography().getInitialHash(item.objectMessage)), item)
             added++
         }
 
-        override fun putObject(`object`: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long) {
-            items.put(InventoryVector(cryptography().getInitialHash(`object`)), ProofOfWorkRepository.Item(`object`, nonceTrialsPerByte, extraBytes))
+        override fun putObject(objectMessage: ObjectMessage, nonceTrialsPerByte: Long, extraBytes: Long) {
+            items.put(InventoryVector(cryptography().getInitialHash(objectMessage)), ProofOfWorkRepository.Item(objectMessage, nonceTrialsPerByte, extraBytes))
             added++
         }
 
@@ -87,39 +87,42 @@ class BitmessageContextTest {
             removed = 0
         }
     })
+    private val testPowEngine = spy(object : ProofOfWorkEngine {
+        override fun calculateNonce(initialHash: ByteArray, target: ByteArray, callback: ProofOfWorkEngine.Callback) {
+            thread { callback.onNonceCalculated(initialHash, ByteArray(8)) }
+        }
+    })
+    private var ctx = BitmessageContext.Builder()
+        .addressRepo(mock())
+        .cryptography(BouncyCryptography())
+        .inventory(inventory)
+        .listener(listener)
+        .messageRepo(mock())
+        .networkHandler(mock())
+        .nodeRegistry(mock())
+        .labeler(spy(DefaultLabeler()))
+        .powRepo(testPowRepo)
+        .proofOfWorkEngine(testPowEngine)
+        .build()
+
+    init {
+        TTL.msg = 2 * MINUTE
+    }
 
     @Before
     fun setUp() {
-        Singleton.initialize(BouncyCryptography())
-        ctx = BitmessageContext.Builder()
-            .addressRepo(mock())
-            .cryptography(cryptography())
-            .inventory(inventory)
-            .listener(listener)
-            .messageRepo(mock())
-            .networkHandler(mock())
-            .nodeRegistry(mock())
-            .labeler(spy(DefaultLabeler()))
-            .powRepo(testPowRepo)
-            .proofOfWorkEngine(spy(object : ProofOfWorkEngine {
-                override fun calculateNonce(initialHash: ByteArray, target: ByteArray, callback: ProofOfWorkEngine.Callback) {
-                    callback.onNonceCalculated(initialHash, ByteArray(8))
-                }
-            }))
-            .build()
-        TTL.msg = 2 * MINUTE
         testPowRepo.reset()
     }
 
     @Test
     fun `ensure contact is saved and pubkey requested`() {
         val contact = BitmessageAddress("BM-opWQhvk9xtMFvQA2Kvetedpk8LkbraWHT")
-        whenever(ctx.addresses.getAddress(contact.address)).thenReturn(contact)
+        doReturn(contact).whenever(ctx.addresses).getAddress(eq(contact.address))
 
         ctx.addContact(contact)
 
-        verify(ctx.addresses, timeout(1000).atLeastOnce()).save(contact)
-        verify(ctx.internals.proofOfWorkEngine, timeout(1000)).calculateNonce(any(), any(), any())
+        verify(ctx.addresses, timeout(1000).atLeastOnce()).save(eq(contact))
+        verify(testPowEngine, timeout(1000)).calculateNonce(any(), any(), any())
     }
 
     @Test
@@ -132,7 +135,7 @@ class BitmessageContextTest {
         ctx.addContact(contact)
 
         verify(ctx.addresses, times(1)).save(contact)
-        verify(ctx.internals.proofOfWorkEngine, never()).calculateNonce(any(), any(), any())
+        verify(testPowEngine, never()).calculateNonce(any(), any(), any())
     }
 
     @Test
@@ -155,7 +158,7 @@ class BitmessageContextTest {
         ctx.addContact(contact)
 
         verify(ctx.addresses, atLeastOnce()).save(contact)
-        verify(ctx.internals.proofOfWorkEngine, never()).calculateNonce(any(), any(), any())
+        verify(testPowEngine, never()).calculateNonce(any(), any(), any())
     }
 
     @Test
@@ -179,7 +182,7 @@ class BitmessageContextTest {
         ctx.addContact(contact)
 
         verify(ctx.addresses, atLeastOnce()).save(any())
-        verify(ctx.internals.proofOfWorkEngine, never()).calculateNonce(any(), any(), any())
+        verify(testPowEngine, never()).calculateNonce(any(), any(), any())
     }
 
     @Test
@@ -209,9 +212,9 @@ class BitmessageContextTest {
     fun `ensure message is sent`() {
         ctx.send(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"), TestUtils.loadContact(),
             "Subject", "Message")
+        verify(ctx.internals.proofOfWorkRepository, timeout(10000)).putObject(
+            argThat { payload.type == ObjectType.MSG }, eq(1000L), eq(1000L))
         assertEquals(2, testPowRepo.added)
-        verify(ctx.internals.proofOfWorkRepository, timeout(10000).atLeastOnce())
-            .putObject(argThat { payload.type == ObjectType.MSG }, eq(1000L), eq(1000L))
         verify(ctx.messages, timeout(10000).atLeastOnce()).save(argThat { type == Type.MSG })
     }
 
@@ -236,10 +239,9 @@ class BitmessageContextTest {
     fun `ensure broadcast is sent`() {
         ctx.broadcast(TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8"),
             "Subject", "Message")
-        verify(ctx.internals.proofOfWorkRepository, timeout(10000).atLeastOnce())
+        verify(ctx.internals.proofOfWorkRepository, timeout(1000).atLeastOnce())
             .putObject(argThat { payload.type == ObjectType.BROADCAST }, eq(1000L), eq(1000L))
-        verify(ctx.internals.proofOfWorkEngine)
-            .calculateNonce(any(), any(), any())
+        verify(testPowEngine).calculateNonce(any(), any(), any())
         verify(ctx.messages, timeout(10000).atLeastOnce()).save(argThat { type == Type.BROADCAST })
     }
 
@@ -265,7 +267,7 @@ class BitmessageContextTest {
     fun `ensure deterministic addresses are created`() {
         val expected_size = 8
         val addresses = ctx.createDeterministicAddresses("test", expected_size, 4, 1, false)
-        assertEquals(expected_size.toLong(), addresses.size.toLong())
+        assertEquals(expected_size, addresses.size)
         val expected = HashSet<String>(expected_size)
         expected.add("BM-2cWFkyuXXFw6d393RGnin2RpSXj8wxtt6F")
         expected.add("BM-2cX8TF9vuQZEWvT7UrEeq1HN9dgiSUPLEN")
@@ -285,7 +287,7 @@ class BitmessageContextTest {
     fun `ensure short deterministic addresses are created`() {
         val expected_size = 1
         val addresses = ctx.createDeterministicAddresses("test", expected_size, 4, 1, true)
-        assertEquals(expected_size.toLong(), addresses.size.toLong())
+        assertEquals(expected_size, addresses.size)
         val expected = HashSet<String>(expected_size)
         expected.add("BM-NBGyBAEp6VnBkFWKpzUSgxuTqVdWPi78")
         for (a in addresses) {
diff --git a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.kt b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.kt
index dc30105..a96430f 100644
--- a/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/DefaultMessageListenerTest.kt
@@ -16,6 +16,7 @@
 
 package ch.dissem.bitmessage
 
+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
@@ -26,9 +27,12 @@ import ch.dissem.bitmessage.entity.payload.GetPubkey
 import ch.dissem.bitmessage.entity.payload.Msg
 import ch.dissem.bitmessage.entity.payload.ObjectType
 import ch.dissem.bitmessage.factory.Factory
+import ch.dissem.bitmessage.ports.ProofOfWorkRepository
 import ch.dissem.bitmessage.utils.Singleton
 import ch.dissem.bitmessage.utils.TestBase
 import ch.dissem.bitmessage.utils.TestUtils
+import ch.dissem.bitmessage.utils.UnixTime.MINUTE
+import ch.dissem.bitmessage.utils.UnixTime.now
 import com.nhaarman.mockito_kotlin.*
 import org.junit.Before
 import org.junit.Test
@@ -40,7 +44,7 @@ class DefaultMessageListenerTest : TestBase() {
     private lateinit var listener: DefaultMessageListener
 
     private val ctx = TestUtils.mockedInternalContext(
-        cryptography = Singleton.cryptography()
+        cryptography = BouncyCryptography()
     )
 
     @Before
@@ -52,10 +56,13 @@ class DefaultMessageListenerTest : TestBase() {
     fun `ensure pubkey is sent on request`() {
         val identity = TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8")
         whenever(ctx.addressRepository.findIdentity(any())).thenReturn(identity)
-        listener.receive(ObjectMessage.Builder()
-            .stream(2)
-            .payload(GetPubkey(BitmessageAddress("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8")))
-            .build())
+        val objectMessage = ObjectMessage(
+            stream = 2,
+            payload = GetPubkey(BitmessageAddress("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8")),
+            expiresTime = now + MINUTE
+        )
+        whenever(ctx.proofOfWorkRepository.getItem(any())).thenReturn(ProofOfWorkRepository.Item(objectMessage, 1000L, 1000L))
+        listener.receive(objectMessage)
         verify(ctx.proofOfWorkRepository).putObject(argThat { type == ObjectType.PUBKEY.number }, any(), any())
     }
 
@@ -73,6 +80,7 @@ class DefaultMessageListenerTest : TestBase() {
             .build()
         objectMessage.sign(identity.privateKey!!)
         objectMessage.encrypt(Singleton.cryptography().createPublicKey(identity.publicDecryptionKey))
+        whenever(ctx.proofOfWorkRepository.getItem(any())).thenReturn(ProofOfWorkRepository.Item(objectMessage, 1000L, 1000L))
         listener.receive(objectMessage)
 
         verify(ctx.addressRepository).save(eq(contact))
diff --git a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.kt b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.kt
index 23a31a9..c244ce0 100644
--- a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.kt
@@ -77,24 +77,24 @@ class ProofOfWorkServiceTest {
         val identity = TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8")
         val address = TestUtils.loadContact()
         val plaintext = Plaintext.Builder(MSG).from(identity).to(address).message("", "").build()
-        val `object` = ObjectMessage(
+        val objectMessage = ObjectMessage(
             expiresTime = 0,
             stream = 1,
             payload = Msg(plaintext)
         )
-        `object`.sign(identity.privateKey!!)
-        `object`.encrypt(address.pubkey!!)
+        objectMessage.sign(identity.privateKey!!)
+        objectMessage.encrypt(address.pubkey!!)
         val initialHash = ByteArray(64)
         val nonce = byteArrayOf(1, 2, 3, 4, 5, 6, 7, 8)
 
-        whenever(ctx.proofOfWorkRepository.getItem(initialHash)).thenReturn(ProofOfWorkRepository.Item(`object`, 1001, 1002))
+        whenever(ctx.proofOfWorkRepository.getItem(initialHash)).thenReturn(ProofOfWorkRepository.Item(objectMessage, 1001, 1002))
         whenever(ctx.messageRepository.getMessage(initialHash)).thenReturn(plaintext)
 
         ctx.proofOfWorkService.onNonceCalculated(initialHash, nonce)
 
         verify(ctx.proofOfWorkRepository).removeObject(eq(initialHash))
-        verify(ctx.inventory).storeObject(eq(`object`))
-        verify(ctx.networkHandler).offer(eq(`object`.inventoryVector))
-        assertThat(plaintext.inventoryVector, equalTo(`object`.inventoryVector))
+        verify(ctx.inventory).storeObject(eq(objectMessage))
+        verify(ctx.networkHandler).offer(eq(objectMessage.inventoryVector))
+        assertThat(plaintext.inventoryVector, equalTo(objectMessage.inventoryVector))
     }
 }
diff --git a/core/src/test/java/ch/dissem/bitmessage/SignatureTest.kt b/core/src/test/java/ch/dissem/bitmessage/SignatureTest.kt
index 5fe9f7a..a3b965c 100644
--- a/core/src/test/java/ch/dissem/bitmessage/SignatureTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/SignatureTest.kt
@@ -29,9 +29,9 @@ import org.junit.Test
 class SignatureTest : TestBase() {
     @Test
     fun `ensure validation works`() {
-        val `object` = TestUtils.loadObjectMessage(3, "V3Pubkey.payload")
-        val pubkey = `object`.payload as Pubkey
-        assertTrue(`object`.isSignatureValid(pubkey))
+        val objectMessage = TestUtils.loadObjectMessage(3, "V3Pubkey.payload")
+        val pubkey = objectMessage.payload as Pubkey
+        assertTrue(objectMessage.isSignatureValid(pubkey))
     }
 
     @Test
@@ -52,11 +52,11 @@ class SignatureTest : TestBase() {
     fun `ensure message is properly signed`() {
         val identity = TestUtils.loadIdentity("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8")
 
-        val `object` = TestUtils.loadObjectMessage(3, "V1Msg.payload")
-        val msg = `object`.payload as Msg
+        val objectMessage = TestUtils.loadObjectMessage(3, "V1Msg.payload")
+        val msg = objectMessage.payload as Msg
         msg.decrypt(identity.privateKey!!.privateEncryptionKey)
         assertNotNull(msg.plaintext)
         assertEquals(TestUtils.loadContact().pubkey, msg.plaintext!!.from.pubkey)
-        assertTrue(`object`.isSignatureValid(msg.plaintext!!.from.pubkey!!))
+        assertTrue(objectMessage.isSignatureValid(msg.plaintext!!.from.pubkey!!))
     }
 }
diff --git a/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.kt b/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.kt
index 1177ea2..95dcee1 100644
--- a/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/entity/BitmessageAddressTest.kt
@@ -31,9 +31,9 @@ import java.util.*
 class BitmessageAddressTest : TestBase() {
     @Test
     fun `ensure feature flag is calculated correctly`() {
-        Assert.assertEquals(1, Pubkey.Feature.bitfield(DOES_ACK).toLong())
-        assertEquals(2, Pubkey.Feature.bitfield(INCLUDE_DESTINATION).toLong())
-        assertEquals(3, Pubkey.Feature.bitfield(DOES_ACK, INCLUDE_DESTINATION).toLong())
+        Assert.assertEquals(1, Pubkey.Feature.bitfield(DOES_ACK))
+        assertEquals(2, Pubkey.Feature.bitfield(INCLUDE_DESTINATION))
+        assertEquals(3, Pubkey.Feature.bitfield(DOES_ACK, INCLUDE_DESTINATION))
     }
 
     @Test
@@ -84,9 +84,9 @@ class BitmessageAddressTest : TestBase() {
         val address = BitmessageAddress("BM-2D9Vc5rFxxR5vTi53T9gkLfemViHRMVLQZ")
         Assert.assertArrayEquals(Bytes.fromHex("007402be6e76c3cb87caa946d0c003a3d4d8e1d5"), address.ripe)
 
-        val `object` = TestUtils.loadObjectMessage(3, "V3Pubkey.payload")
-        val pubkey = `object`.payload as Pubkey
-        assertTrue(`object`.isSignatureValid(pubkey))
+        val objectMessage = TestUtils.loadObjectMessage(3, "V3Pubkey.payload")
+        val pubkey = objectMessage.payload as Pubkey
+        assertTrue(objectMessage.isSignatureValid(pubkey))
         try {
             address.pubkey = pubkey
         } catch (e: Exception) {
@@ -100,10 +100,10 @@ class BitmessageAddressTest : TestBase() {
     @Test
     fun `ensure V4Pubkey can be imported`() {
         val address = BitmessageAddress("BM-2cXxfcSetKnbHJX2Y85rSkaVpsdNUZ5q9h")
-        val `object` = TestUtils.loadObjectMessage(4, "V4Pubkey.payload")
-        `object`.decrypt(address.publicDecryptionKey)
-        val pubkey = `object`.payload as V4Pubkey
-        assertTrue(`object`.isSignatureValid(pubkey))
+        val objectMessage = TestUtils.loadObjectMessage(4, "V4Pubkey.payload")
+        objectMessage.decrypt(address.publicDecryptionKey)
+        val pubkey = objectMessage.payload as V4Pubkey
+        assertTrue(objectMessage.isSignatureValid(pubkey))
         try {
             address.pubkey = pubkey
         } catch (e: Exception) {
diff --git a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.kt b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.kt
index a9fbfea..22b2d4f 100644
--- a/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/entity/SerializationTest.kt
@@ -170,12 +170,12 @@ class SerializationTest : TestBase() {
     private fun doTest(resourceName: String, version: Int, expectedPayloadType: Class<*>) {
         val data = TestUtils.getBytes(resourceName)
         val `in` = ByteArrayInputStream(data)
-        val `object` = Factory.getObjectMessage(version, `in`, data.size)
+        val objectMessage = Factory.getObjectMessage(version, `in`, data.size)
         val out = ByteArrayOutputStream()
-        assertNotNull(`object`)
-        `object`!!.write(out)
+        assertNotNull(objectMessage)
+        objectMessage!!.write(out)
         assertArrayEquals(data, out.toByteArray())
-        assertEquals(expectedPayloadType.canonicalName, `object`.payload.javaClass.canonicalName)
+        assertEquals(expectedPayloadType.canonicalName, objectMessage.payload.javaClass.canonicalName)
     }
 
     @Test
diff --git a/core/src/test/java/ch/dissem/bitmessage/testutils/TestInventory.kt b/core/src/test/java/ch/dissem/bitmessage/testutils/TestInventory.kt
index f147151..fcdae32 100644
--- a/core/src/test/java/ch/dissem/bitmessage/testutils/TestInventory.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/testutils/TestInventory.kt
@@ -42,12 +42,12 @@ class TestInventory : Inventory {
         return ArrayList(inventory.values)
     }
 
-    override fun storeObject(`object`: ObjectMessage) {
-        inventory.put(`object`.inventoryVector, `object`)
+    override fun storeObject(objectMessage: ObjectMessage) {
+        inventory.put(objectMessage.inventoryVector, objectMessage)
     }
 
-    override fun contains(`object`: ObjectMessage): Boolean {
-        return inventory.containsKey(`object`.inventoryVector)
+    override fun contains(objectMessage: ObjectMessage): Boolean {
+        return inventory.containsKey(objectMessage.inventoryVector)
     }
 
     override fun cleanup() {
diff --git a/core/src/test/java/ch/dissem/bitmessage/utils/CollectionsTest.kt b/core/src/test/java/ch/dissem/bitmessage/utils/CollectionsTest.kt
index dcfad1f..bfb3fe5 100644
--- a/core/src/test/java/ch/dissem/bitmessage/utils/CollectionsTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/utils/CollectionsTest.kt
@@ -27,6 +27,6 @@ class CollectionsTest {
     fun `ensure select random returns maximum possible items`() {
         val list = LinkedList<Int>()
         list += 0..9
-        assertEquals(9, Collections.selectRandom(9, list).size.toLong())
+        assertEquals(9, Collections.selectRandom(9, list).size)
     }
 }
diff --git a/core/src/test/java/ch/dissem/bitmessage/utils/ConversationServiceTest.kt b/core/src/test/java/ch/dissem/bitmessage/utils/ConversationServiceTest.kt
index 97e1a2d..cb26e5f 100644
--- a/core/src/test/java/ch/dissem/bitmessage/utils/ConversationServiceTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/utils/ConversationServiceTest.kt
@@ -16,7 +16,6 @@
 
 package ch.dissem.bitmessage.utils
 
-import ch.dissem.bitmessage.cryptography.bc.BouncyCryptography
 import ch.dissem.bitmessage.entity.BitmessageAddress
 import ch.dissem.bitmessage.entity.Plaintext
 import ch.dissem.bitmessage.entity.Plaintext.Type.MSG
@@ -30,19 +29,13 @@ import org.junit.Assert.assertThat
 import org.junit.Test
 import java.util.*
 
-class ConversationServiceTest {
+class ConversationServiceTest : TestBase() {
     private val alice = BitmessageAddress("BM-2cSqjfJ8xK6UUn5Rw3RpdGQ9RsDkBhWnS8")
     private val bob = BitmessageAddress("BM-2cTtkBnb4BUYDndTKun6D9PjtueP2h1bQj")
 
     private val messageRepository = mock<MessageRepository>()
     private val conversationService = spy(ConversationService(messageRepository))
 
-    companion object {
-        init {
-            Singleton.initialize(BouncyCryptography())
-        }
-    }
-
     @Test
     fun `ensure conversation is sorted properly`() {
         MockitoKotlin.registerInstanceCreator { UUID.randomUUID() }
diff --git a/core/src/test/java/ch/dissem/bitmessage/utils/EncodeTest.kt b/core/src/test/java/ch/dissem/bitmessage/utils/EncodeTest.kt
index 9027162..0fa4361 100644
--- a/core/src/test/java/ch/dissem/bitmessage/utils/EncodeTest.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/utils/EncodeTest.kt
@@ -111,11 +111,11 @@ class EncodeTest {
 
 
     fun checkBytes(stream: ByteArrayOutputStream, vararg bytes: Int) {
-        assertEquals(bytes.size.toLong(), stream.size().toLong())
+        assertEquals(bytes.size, stream.size())
         val streamBytes = stream.toByteArray()
 
         for (i in bytes.indices) {
-            assertEquals(bytes[i].toByte().toLong(), streamBytes[i].toLong())
+            assertEquals(bytes[i].toByte(), streamBytes[i])
         }
     }
 }
diff --git a/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.kt b/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.kt
index 397f926..6f72ba3 100644
--- a/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.kt
+++ b/core/src/test/java/ch/dissem/bitmessage/utils/TestUtils.kt
@@ -43,7 +43,7 @@ object TestUtils {
 
     @JvmStatic fun int16(number: Int): ByteArray {
         val out = ByteArrayOutputStream()
-        Encode.int16(number.toLong(), out)
+        Encode.int16(number, out)
         return out.toByteArray()
     }
 
@@ -85,9 +85,9 @@ object TestUtils {
     @Throws(DecryptionFailedException::class)
     @JvmStatic fun loadContact(): BitmessageAddress {
         val address = BitmessageAddress("BM-2cXxfcSetKnbHJX2Y85rSkaVpsdNUZ5q9h")
-        val `object` = TestUtils.loadObjectMessage(3, "V4Pubkey.payload")
-        `object`.decrypt(address.publicDecryptionKey)
-        address.pubkey = `object`.payload as V4Pubkey
+        val objectMessage = TestUtils.loadObjectMessage(3, "V4Pubkey.payload")
+        objectMessage.decrypt(address.publicDecryptionKey)
+        address.pubkey = objectMessage.payload as V4Pubkey
         return address
     }
 
diff --git a/cryptography-bc/src/main/java/ch/dissem/bitmessage/cryptography/bc/BouncyCryptography.kt b/cryptography-bc/src/main/java/ch/dissem/bitmessage/cryptography/bc/BouncyCryptography.kt
index 89e38e2..5ce7027 100644
--- a/cryptography-bc/src/main/java/ch/dissem/bitmessage/cryptography/bc/BouncyCryptography.kt
+++ b/cryptography-bc/src/main/java/ch/dissem/bitmessage/cryptography/bc/BouncyCryptography.kt
@@ -40,8 +40,7 @@ import java.util.*
  * As Spongycastle can't be used on the Oracle JVM, and Bouncycastle doesn't work properly on Android (thanks, Google),
  * this is the Bouncycastle implementation.
  */
-object BouncyCryptography : AbstractCryptography(BouncyCastleProvider()) {
-    private val EC_CURVE_PARAMETERS = CustomNamedCurves.getByName("secp256k1")
+class BouncyCryptography : AbstractCryptography(BouncyCastleProvider()) {
 
     override fun crypt(encrypt: Boolean, data: ByteArray, key_e: ByteArray, initializationVector: ByteArray): ByteArray {
         val cipher = PaddedBufferedBlockCipher(
@@ -119,4 +118,8 @@ object BouncyCryptography : AbstractCryptography(BouncyCastleProvider()) {
             BigInteger(1, y)
         ).getEncoded(false)
     }
+
+    companion object {
+        private val EC_CURVE_PARAMETERS = CustomNamedCurves.getByName("secp256k1")
+    }
 }
diff --git a/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt b/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt
index c51c296..1897512 100644
--- a/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt
+++ b/cryptography-bc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt
@@ -163,7 +163,7 @@ class CryptographyTest {
         val TEST_RIPEMD160 = DatatypeConverter.parseHexBinary(""
             + "cd566972b5e50104011a92b59fa8e0b1234851ae")
 
-        private val crypto = BouncyCryptography
+        private val crypto = BouncyCryptography()
 
         init {
             Singleton.initialize(crypto)
diff --git a/cryptography-sc/src/main/java/ch/dissem/bitmessage/cryptography/sc/SpongyCryptography.kt b/cryptography-sc/src/main/java/ch/dissem/bitmessage/cryptography/sc/SpongyCryptography.kt
index f2e2320..1465fb3 100644
--- a/cryptography-sc/src/main/java/ch/dissem/bitmessage/cryptography/sc/SpongyCryptography.kt
+++ b/cryptography-sc/src/main/java/ch/dissem/bitmessage/cryptography/sc/SpongyCryptography.kt
@@ -40,8 +40,7 @@ import java.util.*
  * As Spongycastle can't be used on the Oracle JVM, and Bouncycastle doesn't work properly on Android (thanks, Google),
  * this is the Spongycastle implementation.
  */
-object SpongyCryptography : AbstractCryptography(BouncyCastleProvider()) {
-    private val EC_CURVE_PARAMETERS = CustomNamedCurves.getByName("secp256k1")
+class SpongyCryptography : AbstractCryptography(BouncyCastleProvider()) {
 
     override fun crypt(encrypt: Boolean, data: ByteArray, key_e: ByteArray, initializationVector: ByteArray): ByteArray {
         val cipher = PaddedBufferedBlockCipher(
@@ -119,4 +118,8 @@ object SpongyCryptography : AbstractCryptography(BouncyCastleProvider()) {
             BigInteger(1, y)
         ).getEncoded(false)
     }
+
+    companion object {
+        private val EC_CURVE_PARAMETERS = CustomNamedCurves.getByName("secp256k1")
+    }
 }
diff --git a/cryptography-sc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt b/cryptography-sc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt
index c8eafe0..15a9313 100644
--- a/cryptography-sc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt
+++ b/cryptography-sc/src/test/java/ch/dissem/bitmessage/security/CryptographyTest.kt
@@ -162,7 +162,7 @@ class CryptographyTest {
         val TEST_RIPEMD160 = DatatypeConverter.parseHexBinary(""
             + "cd566972b5e50104011a92b59fa8e0b1234851ae")
 
-        private val crypto = SpongyCryptography
+        private val crypto = SpongyCryptography()
 
         init {
             Singleton.initialize(crypto)
diff --git a/demo/src/main/java/ch/dissem/bitmessage/demo/Main.java b/demo/src/main/java/ch/dissem/bitmessage/demo/Main.java
index 2c9ca8e..1da2910 100644
--- a/demo/src/main/java/ch/dissem/bitmessage/demo/Main.java
+++ b/demo/src/main/java/ch/dissem/bitmessage/demo/Main.java
@@ -61,7 +61,7 @@ public class Main {
             .messageRepo(new JdbcMessageRepository(jdbcConfig))
             .powRepo(new JdbcProofOfWorkRepository(jdbcConfig))
             .networkHandler(new NioNetworkHandler())
-            .cryptography(BouncyCryptography.INSTANCE)
+            .cryptography(new BouncyCryptography())
             .port(48444);
         if (options.localPort != null) {
             ctxBuilder.nodeRegistry(new NodeRegistry() {
diff --git a/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java b/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
index 293741f..224cc1a 100644
--- a/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
+++ b/demo/src/test/java/ch/dissem/bitmessage/SystemTest.java
@@ -19,7 +19,6 @@ package ch.dissem.bitmessage;
 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.networking.nio.NioNetworkHandler;
 import ch.dissem.bitmessage.ports.DefaultLabeler;
 import ch.dissem.bitmessage.ports.Labeler;
@@ -29,14 +28,10 @@ import ch.dissem.bitmessage.utils.TTL;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.Parameterized;
 import org.mockito.Mockito;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.Arrays;
-import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 
@@ -49,74 +44,62 @@ import static org.mockito.ArgumentMatchers.any;
 /**
  * @author Christian Basler
  */
-@RunWith(Parameterized.class)
 public class SystemTest {
     private static int port = 6000;
-    private final NetworkHandler aliceNetworkHandler;
-    private final NetworkHandler bobNetworkHandler;
 
     private BitmessageContext alice;
-    private TestListener aliceListener = new TestListener();
-    private Labeler aliceLabeler = Mockito.spy(new DebugLabeler("Alice"));
     private BitmessageAddress aliceIdentity;
+    private Labeler aliceLabeler;
 
     private BitmessageContext bob;
-    private TestListener bobListener = new TestListener();
+    private TestListener bobListener;
     private BitmessageAddress bobIdentity;
 
-    public SystemTest(NetworkHandler peer, NetworkHandler node) {
-        this.aliceNetworkHandler = peer;
-        this.bobNetworkHandler = node;
-    }
-
-    @Parameterized.Parameters
-    @SuppressWarnings("deprecation")
-    public static List<Object[]> parameters() {
-        return Arrays.asList(new Object[][]{
-            {new NioNetworkHandler(), new DefaultNetworkHandler()},
-            {new NioNetworkHandler(), new NioNetworkHandler()}
-        });
-    }
-
     @Before
     public void setUp() {
-        int alicePort = port++;
-        int bobPort = port++;
         TTL.msg(5 * MINUTE);
         TTL.getpubkey(5 * MINUTE);
         TTL.pubkey(5 * MINUTE);
-        JdbcConfig aliceDB = new JdbcConfig("jdbc:h2:mem:alice;DB_CLOSE_DELAY=-1", "sa", "");
-        alice = new BitmessageContext.Builder()
-            .addressRepo(new JdbcAddressRepository(aliceDB))
-            .inventory(new JdbcInventory(aliceDB))
-            .messageRepo(new JdbcMessageRepository(aliceDB))
-            .powRepo(new JdbcProofOfWorkRepository(aliceDB))
-            .port(alicePort)
-            .nodeRegistry(new TestNodeRegistry(bobPort))
-            .networkHandler(aliceNetworkHandler)
-            .cryptography(BouncyCryptography.INSTANCE)
-            .listener(aliceListener)
-            .labeler(aliceLabeler)
-            .build();
-        alice.startup();
-        aliceIdentity = alice.createIdentity(false, DOES_ACK);
-
-        JdbcConfig bobDB = new JdbcConfig("jdbc:h2:mem:bob;DB_CLOSE_DELAY=-1", "sa", "");
-        bob = new BitmessageContext.Builder()
-            .addressRepo(new JdbcAddressRepository(bobDB))
-            .inventory(new JdbcInventory(bobDB))
-            .messageRepo(new JdbcMessageRepository(bobDB))
-            .powRepo(new JdbcProofOfWorkRepository(bobDB))
-            .port(bobPort)
-            .nodeRegistry(new TestNodeRegistry(alicePort))
-            .networkHandler(bobNetworkHandler)
-            .cryptography(BouncyCryptography.INSTANCE)
-            .listener(bobListener)
-            .labeler(new DebugLabeler("Bob"))
-            .build();
-        bob.startup();
-        bobIdentity = bob.createIdentity(false, DOES_ACK);
 
+        int alicePort = port++;
+        int bobPort = port++;
+        {
+            JdbcConfig aliceDB = new JdbcConfig("jdbc:h2:mem:alice;DB_CLOSE_DELAY=-1", "sa", "");
+            aliceLabeler = Mockito.spy(new DebugLabeler("Alice"));
+            TestListener aliceListener = new TestListener();
+            alice = new BitmessageContext.Builder()
+                .addressRepo(new JdbcAddressRepository(aliceDB))
+                .inventory(new JdbcInventory(aliceDB))
+                .messageRepo(new JdbcMessageRepository(aliceDB))
+                .powRepo(new JdbcProofOfWorkRepository(aliceDB))
+                .port(alicePort)
+                .nodeRegistry(new TestNodeRegistry(bobPort))
+                .networkHandler(new NioNetworkHandler())
+                .cryptography(new BouncyCryptography())
+                .listener(aliceListener)
+                .labeler(aliceLabeler)
+                .build();
+            alice.startup();
+            aliceIdentity = alice.createIdentity(false, DOES_ACK);
+        }
+        {
+            JdbcConfig bobDB = new JdbcConfig("jdbc:h2:mem:bob;DB_CLOSE_DELAY=-1", "sa", "");
+            bobListener = new TestListener();
+            bob = new BitmessageContext.Builder()
+                .addressRepo(new JdbcAddressRepository(bobDB))
+                .inventory(new JdbcInventory(bobDB))
+                .messageRepo(new JdbcMessageRepository(bobDB))
+                .powRepo(new JdbcProofOfWorkRepository(bobDB))
+                .port(bobPort)
+                .nodeRegistry(new TestNodeRegistry(alicePort))
+                .networkHandler(new NioNetworkHandler())
+                .cryptography(new BouncyCryptography())
+                .listener(bobListener)
+                .labeler(new DebugLabeler("Bob"))
+                .build();
+            bob.startup();
+            bobIdentity = bob.createIdentity(false, DOES_ACK);
+        }
         ((DebugLabeler) alice.labeler()).init(aliceIdentity, bobIdentity);
         ((DebugLabeler) bob.labeler()).init(aliceIdentity, bobIdentity);
     }
diff --git a/extensions/src/main/kotlin/ch/dissem/bitmessage/extensions/CryptoCustomMessage.kt b/extensions/src/main/kotlin/ch/dissem/bitmessage/extensions/CryptoCustomMessage.kt
index 1c76bdb..d5a2349 100644
--- a/extensions/src/main/kotlin/ch/dissem/bitmessage/extensions/CryptoCustomMessage.kt
+++ b/extensions/src/main/kotlin/ch/dissem/bitmessage/extensions/CryptoCustomMessage.kt
@@ -65,7 +65,7 @@ class CryptoCustomMessage<T : Streamable> : CustomMessage {
 
         Encode.varInt(identity.version, out)
         Encode.varInt(identity.stream, out)
-        Encode.int32(privateKey.pubkey.behaviorBitfield.toLong(), out)
+        Encode.int32(privateKey.pubkey.behaviorBitfield, out)
         out.write(privateKey.pubkey.signingKey, 1, 64)
         out.write(privateKey.pubkey.encryptionKey, 1, 64)
         if (identity.version >= 3) {
@@ -114,7 +114,7 @@ class CryptoCustomMessage<T : Streamable> : CustomMessage {
         container?.write(out) ?: throw IllegalStateException("not encrypted yet")
     }
 
-    interface Reader<T> {
+    interface Reader<out T> {
         fun read(sender: BitmessageAddress, `in`: InputStream): T
     }
 
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/nio/NioNetworkHandler.java b/networking/src/main/java/ch/dissem/bitmessage/networking/nio/NioNetworkHandler.java
index 7f6dc5d..40e79d0 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/nio/NioNetworkHandler.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/nio/NioNetworkHandler.java
@@ -25,10 +25,10 @@ import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.exception.NodeException;
 import ch.dissem.bitmessage.factory.V3MessageReader;
-import ch.dissem.bitmessage.networking.AbstractConnection;
 import ch.dissem.bitmessage.ports.NetworkHandler;
 import ch.dissem.bitmessage.utils.DebugUtils;
 import ch.dissem.bitmessage.utils.Property;
+import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -75,8 +75,9 @@ public class NioNetworkHandler implements NetworkHandler, InternalContext.Contex
 
     private Thread starter;
 
+    @NotNull
     @Override
-    public Future<Void> synchronize(final InetAddress server, final int port, final long timeoutInSeconds) {
+    public Future<Void> synchronize(@NotNull final InetAddress server, final int port, final long timeoutInSeconds) {
         return threadPool.submit(new Callable<Void>() {
             @Override
             public Void call() throws Exception {
@@ -97,8 +98,9 @@ public class NioNetworkHandler implements NetworkHandler, InternalContext.Contex
         });
     }
 
+    @NotNull
     @Override
-    public CustomMessage send(InetAddress server, int port, CustomMessage request) {
+    public CustomMessage send(@NotNull InetAddress server, int port, @NotNull CustomMessage request) {
         try (SocketChannel channel = SocketChannel.open(new InetSocketAddress(server, port))) {
             channel.configureBlocking(true);
             ByteBuffer headerBuffer = ByteBuffer.allocate(HEADER_SIZE);
@@ -129,7 +131,7 @@ public class NioNetworkHandler implements NetworkHandler, InternalContext.Contex
             if (networkMessage != null && networkMessage.getPayload() instanceof CustomMessage) {
                 return (CustomMessage) networkMessage.getPayload();
             } else {
-                if (networkMessage == null || networkMessage.getPayload() == null) {
+                if (networkMessage == null) {
                     throw new NodeException("Empty response from node " + server);
                 } else {
                     throw new NodeException("Unexpected response from node " + server + ": "
@@ -391,7 +393,7 @@ public class NioNetworkHandler implements NetworkHandler, InternalContext.Contex
     }
 
     @Override
-    public void offer(InventoryVector iv) {
+    public void offer(@NotNull InventoryVector iv) {
         List<ConnectionInfo> target = new LinkedList<>();
         for (ConnectionInfo connection : connections.keySet()) {
             if (connection.getState() == ACTIVE && !connection.knowsOf(iv)) {
@@ -405,7 +407,7 @@ public class NioNetworkHandler implements NetworkHandler, InternalContext.Contex
     }
 
     @Override
-    public void request(Collection<InventoryVector> inventoryVectors) {
+    public void request(@NotNull Collection<InventoryVector> inventoryVectors) {
         if (!isRunning()) {
             requestedObjects.clear();
             return;
@@ -468,6 +470,7 @@ public class NioNetworkHandler implements NetworkHandler, InternalContext.Contex
         }
     }
 
+    @NotNull
     @Override
     public Property getNetworkStatus() {
         TreeSet<Long> streams = new TreeSet<>();
@@ -520,7 +523,7 @@ public class NioNetworkHandler implements NetworkHandler, InternalContext.Contex
     }
 
     @Override
-    public void setContext(InternalContext context) {
+    public void setContext(@NotNull InternalContext context) {
         this.ctx = context;
     }
 }
diff --git a/networking/src/test/java/ch/dissem/bitmessage/networking/NetworkHandlerTest.java b/networking/src/test/java/ch/dissem/bitmessage/networking/NetworkHandlerTest.java
index a4e7d54..f079ede 100644
--- a/networking/src/test/java/ch/dissem/bitmessage/networking/NetworkHandlerTest.java
+++ b/networking/src/test/java/ch/dissem/bitmessage/networking/NetworkHandlerTest.java
@@ -98,7 +98,7 @@ public class NetworkHandlerTest {
             .port(peerAddress.getPort())
             .nodeRegistry(new TestNodeRegistry())
             .networkHandler(peerNetworkHandler)
-            .cryptography(BouncyCryptography.INSTANCE)
+            .cryptography(new BouncyCryptography())
             .listener(mock(BitmessageContext.Listener.class))
             .customCommandHandler(new CustomCommandHandler() {
                 @Override
@@ -133,7 +133,7 @@ public class NetworkHandlerTest {
             .port(6002)
             .nodeRegistry(new TestNodeRegistry(peerAddress))
             .networkHandler(nodeNetworkHandler)
-            .cryptography(BouncyCryptography.INSTANCE)
+            .cryptography(new BouncyCryptography())
             .listener(mock(BitmessageContext.Listener.class))
             .build();
     }
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcAddressRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcAddressRepository.java
index b296bc3..2f1e107 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcAddressRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcAddressRepository.java
@@ -21,6 +21,7 @@ import ch.dissem.bitmessage.entity.payload.Pubkey;
 import ch.dissem.bitmessage.entity.payload.V3Pubkey;
 import ch.dissem.bitmessage.entity.payload.V4Pubkey;
 import ch.dissem.bitmessage.entity.valueobject.PrivateKey;
+import ch.dissem.bitmessage.exception.ApplicationException;
 import ch.dissem.bitmessage.factory.Factory;
 import ch.dissem.bitmessage.ports.AddressRepository;
 import org.slf4j.Logger;
@@ -137,16 +138,14 @@ public class JdbcAddressRepository extends JdbcHelper implements AddressReposito
         try (
             Connection connection = config.getConnection();
             Statement stmt = connection.createStatement();
-            ResultSet rs = stmt.executeQuery("SELECT COUNT(*) FROM Address " +
+            ResultSet rs = stmt.executeQuery("SELECT '1' FROM Address " +
                 "WHERE address='" + address.getAddress() + "'")
         ) {
-            if (rs.next()) {
-                return rs.getInt(1) > 0;
-            }
+            return rs.next();
         } catch (SQLException e) {
             LOG.error(e.getMessage(), e);
+            throw new ApplicationException(e);
         }
-        return false;
     }
 
     @Override
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
deleted file mode 100644
index e9fffb6..0000000
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.java
+++ /dev/null
@@ -1,344 +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.repository;
-
-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 org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import java.io.IOException;
-import java.io.InputStream;
-import java.sql.*;
-import java.util.ArrayList;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.UUID;
-
-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 final JdbcConfig config;
-
-    public JdbcMessageRepository(JdbcConfig config) {
-        this.config = config;
-    }
-
-    @Override
-    protected List<Label> findLabels(String where) {
-        try (
-            Connection connection = config.getConnection()
-        ) {
-            return findLabels(connection, where);
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-        return new ArrayList<>();
-    }
-
-    private Label getLabel(ResultSet rs) throws SQLException {
-        String typeName = rs.getString("type");
-        Label.Type type = null;
-        if (typeName != null) {
-            type = Label.Type.valueOf(typeName);
-        }
-        Label label = new Label(rs.getString("label"), type, rs.getInt("color"));
-        label.setId(rs.getLong("id"));
-
-        return label;
-    }
-
-    @Override
-    public int countUnread(Label label) {
-        String where;
-        if (label == null) {
-            where = "";
-        } else {
-            where = "id IN (SELECT message_id FROM Message_Label WHERE label_id=" + label.getId() + ") AND ";
-        }
-        where += "id IN (SELECT message_id FROM Message_Label WHERE label_id IN (" +
-            "SELECT id FROM Label WHERE type = '" + Label.Type.UNREAD.name() + "'))";
-
-        try (
-            Connection connection = config.getConnection();
-            Statement stmt = connection.createStatement();
-            ResultSet rs = stmt.executeQuery("SELECT count(*) FROM Message WHERE " + where)
-        ) {
-            if (rs.next()) {
-                return rs.getInt(1);
-            }
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-        return 0;
-    }
-
-    @Override
-    protected 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, initial_hash, status, ttl, retries, next_try, conversation " +
-                    "FROM Message WHERE " + where)
-        ) {
-            while (rs.next()) {
-                byte[] iv = rs.getBytes("iv");
-                InputStream data = rs.getBinaryStream("data");
-                Plaintext.Type type = Plaintext.Type.valueOf(rs.getString("type"));
-                Plaintext.Builder builder = Plaintext.readWithoutSignature(type, data);
-                long id = rs.getLong("id");
-                builder.id(id);
-                builder.IV(InventoryVector.fromHash(iv));
-                builder.from(getCtx().getAddressRepository().getAddress(rs.getString("sender")));
-                builder.to(getCtx().getAddressRepository().getAddress(rs.getString("recipient")));
-                builder.ackData(rs.getBytes("ack_data"));
-                builder.sent(rs.getObject("sent", Long.class));
-                builder.received(rs.getObject("received", Long.class));
-                builder.status(Plaintext.Status.valueOf(rs.getString("status")));
-                builder.ttl(rs.getLong("ttl"));
-                builder.retries(rs.getInt("retries"));
-                builder.nextTry(rs.getObject("next_try", Long.class));
-                builder.conversation(rs.getObject("conversation", UUID.class));
-                builder.labels(findLabels(connection,
-                    "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);
-            }
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-        return result;
-    }
-
-    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 " + where)
-        ) {
-            while (rs.next()) {
-                result.add(getLabel(rs));
-            }
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-        return result;
-    }
-
-    @Override
-    public void save(Plaintext message) {
-        saveContactIfNecessary(message.getFrom());
-        saveContactIfNecessary(message.getTo());
-
-        try (Connection connection = config.getConnection()) {
-            try {
-                connection.setAutoCommit(false);
-                save(connection, message);
-                updateParents(connection, message);
-                updateLabels(connection, message);
-                connection.commit();
-            } catch (IOException | SQLException e) {
-                connection.rollback();
-                throw e;
-            }
-        } catch (IOException | SQLException e) {
-            throw new ApplicationException(e);
-        }
-    }
-
-    private void save(Connection connection, Plaintext message) throws IOException, SQLException {
-        if (message.getId() == null) {
-            insert(connection, message);
-        } else {
-            update(connection, message);
-        }
-    }
-
-    private void updateLabels(Connection connection, Plaintext message) throws SQLException {
-        // remove existing labels
-        try (Statement stmt = connection.createStatement()) {
-            stmt.executeUpdate("DELETE FROM Message_Label WHERE message_id=" + message.getId());
-        }
-        // save new labels
-        try (PreparedStatement ps = connection.prepareStatement("INSERT INTO Message_Label VALUES (" +
-            message.getId() + ", ?)")) {
-            for (Label label : message.getLabels()) {
-                ps.setLong(1, (Long) label.getId());
-                ps.executeUpdate();
-            }
-        }
-    }
-
-    private void updateParents(Connection connection, Plaintext message) throws SQLException {
-        if (message.getInventoryVector() == null || message.getParents().isEmpty()) {
-            // There are no parents to save yet (they are saved in the extended data, that's enough for now)
-            return;
-        }
-        // remove existing parents
-        try (PreparedStatement ps = connection.prepareStatement("DELETE FROM Message_Parent WHERE child=?")) {
-            ps.setBytes(1, message.getInitialHash());
-            ps.executeUpdate();
-        }
-        byte[] childIV = message.getInventoryVector().getHash();
-        // save new parents
-        int order = 0;
-        try (PreparedStatement ps = connection.prepareStatement("INSERT INTO Message_Parent VALUES (?, ?, ?, ?)")) {
-            for (InventoryVector parentIV : message.getParents()) {
-                Plaintext parent = getMessage(parentIV);
-                mergeConversations(connection, parent.getConversationId(), message.getConversationId());
-                order++;
-                ps.setBytes(1, parentIV.getHash());
-                ps.setBytes(2, childIV);
-                ps.setInt(3, order); // FIXME: this might not be necessary
-                ps.setObject(4, message.getConversationId());
-                ps.executeUpdate();
-            }
-        }
-    }
-
-    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, ttl, retries, next_try, conversation) " +
-                "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
-            Statement.RETURN_GENERATED_KEYS)
-        ) {
-            ps.setBytes(1, message.getInventoryVector() == null ? null : message.getInventoryVector().getHash());
-            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.setObject(7, message.getSent());
-            ps.setObject(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.setObject(14, message.getConversationId());
-
-            ps.executeUpdate();
-            // get generated id
-            try (ResultSet rs = ps.getGeneratedKeys()) {
-                rs.next();
-                message.setId(rs.getLong(1));
-            }
-        }
-    }
-
-    private void update(Connection connection, Plaintext message) throws SQLException, IOException {
-        try (PreparedStatement ps = connection.prepareStatement(
-            "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.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.setObject(7, message.getSent());
-            ps.setObject(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();
-        }
-    }
-
-    @Override
-    public void remove(Plaintext message) {
-        try (Connection connection = config.getConnection()) {
-            connection.setAutoCommit(false);
-            try (Statement stmt = connection.createStatement()) {
-                stmt.executeUpdate("DELETE FROM Message_Label WHERE message_id = " + message.getId());
-                stmt.executeUpdate("DELETE FROM Message WHERE id = " + message.getId());
-                connection.commit();
-            } catch (SQLException e) {
-                try {
-                    connection.rollback();
-                } catch (SQLException e1) {
-                    LOG.debug(e1.getMessage(), e);
-                }
-                LOG.error(e.getMessage(), e);
-            }
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-    }
-
-    @Override
-    public List<UUID> findConversations(Label label) {
-        String where;
-        if (label == null) {
-            where = "id NOT IN (SELECT message_id FROM Message_Label)";
-        } else {
-            where = "id IN (SELECT message_id FROM Message_Label WHERE label_id=" + label.getId() + ")";
-        }
-        List<UUID> result = new LinkedList<>();
-        try (
-            Connection connection = config.getConnection();
-            Statement stmt = connection.createStatement();
-            ResultSet rs = stmt.executeQuery(
-                "SELECT DISTINCT conversation FROM Message WHERE " + where)
-        ) {
-            while (rs.next()) {
-                result.add((UUID) rs.getObject(1));
-            }
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-        return result;
-    }
-
-    /**
-     * Replaces every occurrence of the source conversation ID with the target ID
-     *
-     * @param source ID of the conversation to be merged
-     * @param target ID of the merge target
-     */
-    private void mergeConversations(Connection connection, UUID source, UUID target) {
-        try (
-            PreparedStatement ps1 = connection.prepareStatement(
-                "UPDATE Message SET conversation=? WHERE conversation=?");
-            PreparedStatement ps2 = connection.prepareStatement(
-                "UPDATE Message_Parent SET conversation=? WHERE conversation=?")
-        ) {
-            ps1.setObject(1, target);
-            ps1.setObject(2, source);
-            ps1.executeUpdate();
-            ps2.setObject(1, target);
-            ps2.setObject(2, source);
-            ps2.executeUpdate();
-        } catch (SQLException e) {
-            LOG.error(e.getMessage(), e);
-        }
-    }
-}
diff --git a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.kt b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.kt
new file mode 100644
index 0000000..2f4f851
--- /dev/null
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcMessageRepository.kt
@@ -0,0 +1,344 @@
+/*
+ * 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.repository
+
+import ch.dissem.bitmessage.entity.Plaintext
+import ch.dissem.bitmessage.entity.valueobject.InventoryVector
+import ch.dissem.bitmessage.entity.valueobject.Label
+import ch.dissem.bitmessage.ports.AbstractMessageRepository
+import ch.dissem.bitmessage.ports.MessageRepository
+import ch.dissem.bitmessage.repository.JdbcHelper.writeBlob
+import org.slf4j.LoggerFactory
+import java.io.IOException
+import java.sql.Connection
+import java.sql.ResultSet
+import java.sql.SQLException
+import java.sql.Statement
+import java.util.*
+
+class JdbcMessageRepository(private val config: JdbcConfig) : AbstractMessageRepository(), MessageRepository {
+
+    override fun findLabels(where: String): List<Label> {
+        try {
+            config.connection.use {
+                connection ->
+                return findLabels(connection, where)
+            }
+        } catch (e: SQLException) {
+            LOG.error(e.message, e)
+            return ArrayList()
+        }
+    }
+
+    private fun getLabel(rs: ResultSet): Label {
+        val typeName = rs.getString("type")
+        val type = if (typeName == null) {
+            null
+        } else {
+            Label.Type.valueOf(typeName)
+        }
+        val label = Label(rs.getString("label"), type, rs.getInt("color"))
+        label.id = rs.getLong("id")
+
+        return label
+    }
+
+    override fun countUnread(label: Label?): Int {
+        val where = if (label == null) {
+            ""
+        } else {
+            "id IN (SELECT message_id FROM Message_Label WHERE label_id=${label.id}) AND "
+        } + "id IN (SELECT message_id FROM Message_Label WHERE label_id IN (" +
+            "SELECT id FROM Label WHERE type = '" + Label.Type.UNREAD.name + "'))"
+
+        try {
+            config.connection.use { connection ->
+                connection.createStatement().use { stmt ->
+                    stmt.executeQuery("SELECT count(*) FROM Message WHERE $where").use { rs ->
+                        if (rs.next()) {
+                            return rs.getInt(1)
+                        }
+                    }
+                }
+            }
+        } catch (e: SQLException) {
+            LOG.error(e.message, e)
+        }
+        return 0
+    }
+
+    override fun find(where: String): List<Plaintext> {
+        val result = LinkedList<Plaintext>()
+        try {
+            config.connection.use { connection ->
+                connection.createStatement().use { stmt ->
+                    stmt.executeQuery(
+                        """SELECT id, iv, type, sender, recipient, data, ack_data, sent, received, initial_hash, status, ttl, retries, next_try, conversation
+                           FROM Message WHERE $where""").use { rs ->
+                        while (rs.next()) {
+                            val iv = rs.getBytes("iv")
+                            val data = rs.getBinaryStream("data")
+                            val type = Plaintext.Type.valueOf(rs.getString("type"))
+                            val builder = Plaintext.readWithoutSignature(type, data)
+                            val id = rs.getLong("id")
+                            builder.id(id)
+                            builder.IV(InventoryVector.fromHash(iv))
+                            builder.from(ctx.addressRepository.getAddress(rs.getString("sender"))!!)
+                            builder.to(ctx.addressRepository.getAddress(rs.getString("recipient")))
+                            builder.ackData(rs.getBytes("ack_data"))
+                            builder.sent(rs.getObject("sent", Long::class.java))
+                            builder.received(rs.getObject("received", Long::class.java))
+                            builder.status(Plaintext.Status.valueOf(rs.getString("status")))
+                            builder.ttl(rs.getLong("ttl"))
+                            builder.retries(rs.getInt("retries"))
+                            builder.nextTry(rs.getObject("next_try", Long::class.java))
+                            builder.conversation(rs.getObject("conversation", UUID::class.java))
+                            builder.labels(findLabels(connection,
+                                "id IN (SELECT label_id FROM Message_Label WHERE message_id=$id) ORDER BY ord"))
+                            val message = builder.build()
+                            message.initialHash = rs.getBytes("initial_hash")
+                            result.add(message)
+                        }
+                    }
+                }
+            }
+        } catch (e: SQLException) {
+            LOG.error(e.message, e)
+        }
+
+        return result
+    }
+
+    private fun findLabels(connection: Connection, where: String): List<Label> {
+        val result = ArrayList<Label>()
+        try {
+            connection.createStatement().use { stmt ->
+                stmt.executeQuery("SELECT id, label, type, color FROM Label WHERE $where").use { rs ->
+                    while (rs.next()) {
+                        result.add(getLabel(rs))
+                    }
+                }
+            }
+        } catch (e: SQLException) {
+            LOG.error(e.message, e)
+        }
+
+        return result
+    }
+
+    override fun save(message: Plaintext) {
+        saveContactIfNecessary(message.from)
+        saveContactIfNecessary(message.to)
+
+        config.connection.use { connection ->
+            try {
+                connection.autoCommit = false
+                save(connection, message)
+                updateParents(connection, message)
+                updateLabels(connection, message)
+                connection.commit()
+            } catch (e: Exception) {
+                connection.rollback()
+                throw e
+            }
+        }
+    }
+
+    private fun save(connection: Connection, message: Plaintext) {
+        if (message.id == null) {
+            insert(connection, message)
+        } else {
+            update(connection, message)
+        }
+    }
+
+    private fun updateLabels(connection: Connection, message: Plaintext) {
+        // remove existing labels
+        connection.createStatement().use { stmt -> stmt.executeUpdate("DELETE FROM Message_Label WHERE message_id=${message.id!!}") }
+        // save new labels
+        connection.prepareStatement("INSERT INTO Message_Label VALUES (${message.id}, ?)").use { ps ->
+            for (label in message.labels) {
+                ps.setLong(1, (label.id as Long?)!!)
+                ps.executeUpdate()
+            }
+        }
+    }
+
+    private fun updateParents(connection: Connection, message: Plaintext) {
+        if (message.inventoryVector == null || message.parents.isEmpty()) {
+            // There are no parents to save yet (they are saved in the extended data, that's enough for now)
+            return
+        }
+        // remove existing parents
+        connection.prepareStatement("DELETE FROM Message_Parent WHERE child=?").use { ps ->
+            ps.setBytes(1, message.initialHash)
+            ps.executeUpdate()
+        }
+        val childIV = message.inventoryVector!!.hash
+        // save new parents
+        var order = 0
+        connection.prepareStatement("INSERT INTO Message_Parent VALUES (?, ?, ?, ?)").use { ps ->
+            for (parentIV in message.parents) {
+                val parent = getMessage(parentIV)
+                mergeConversations(connection, parent!!.conversationId, message.conversationId)
+                order++
+                ps.setBytes(1, parentIV.hash)
+                ps.setBytes(2, childIV)
+                ps.setInt(3, order) // FIXME: this might not be necessary
+                ps.setObject(4, message.conversationId)
+                ps.executeUpdate()
+            }
+        }
+    }
+
+    private fun insert(connection: Connection, message: Plaintext) {
+        connection.prepareStatement(
+            "INSERT INTO Message (iv, type, sender, recipient, data, ack_data, sent, received, " +
+                "status, initial_hash, ttl, retries, next_try, conversation) " +
+                "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+            Statement.RETURN_GENERATED_KEYS).use { ps ->
+            ps.setBytes(1, if (message.inventoryVector == null) null else message.inventoryVector!!.hash)
+            ps.setString(2, message.type.name)
+            ps.setString(3, message.from.address)
+            ps.setString(4, if (message.to == null) null else message.to!!.address)
+            writeBlob(ps, 5, message)
+            ps.setBytes(6, message.ackData)
+            ps.setObject(7, message.sent)
+            ps.setObject(8, message.received)
+            ps.setString(9, message.status.name)
+            ps.setBytes(10, message.initialHash)
+            ps.setLong(11, message.ttl)
+            ps.setInt(12, message.retries)
+            ps.setObject(13, message.nextTry)
+            ps.setObject(14, message.conversationId)
+
+            ps.executeUpdate()
+            // get generated id
+            ps.generatedKeys.use { rs ->
+                rs.next()
+                message.id = rs.getLong(1)
+            }
+        }
+    }
+
+    @Throws(SQLException::class, IOException::class)
+    private fun update(connection: Connection, message: Plaintext) {
+        connection.prepareStatement(
+            "UPDATE Message SET iv=?, type=?, sender=?, recipient=?, data=?, ack_data=?, sent=?, received=?, " +
+                "status=?, initial_hash=?, ttl=?, retries=?, next_try=? " +
+                "WHERE id=?").use { ps ->
+            ps.setBytes(1, if (message.inventoryVector == null) null else message.inventoryVector!!.hash)
+            ps.setString(2, message.type.name)
+            ps.setString(3, message.from.address)
+            ps.setString(4, if (message.to == null) null else message.to!!.address)
+            writeBlob(ps, 5, message)
+            ps.setBytes(6, message.ackData)
+            ps.setObject(7, message.sent)
+            ps.setObject(8, message.received)
+            ps.setString(9, message.status.name)
+            ps.setBytes(10, message.initialHash)
+            ps.setLong(11, message.ttl)
+            ps.setInt(12, message.retries)
+            ps.setObject(13, message.nextTry)
+            ps.setLong(14, (message.id as Long?)!!)
+            ps.executeUpdate()
+        }
+    }
+
+    override fun remove(message: Plaintext) {
+        try {
+            config.connection.use { connection ->
+                connection.autoCommit = false
+                try {
+                    connection.createStatement().use { stmt ->
+                        stmt.executeUpdate("DELETE FROM Message_Label WHERE message_id = " + message.id!!)
+                        stmt.executeUpdate("DELETE FROM Message WHERE id = " + message.id!!)
+                        connection.commit()
+                    }
+                } catch (e: SQLException) {
+                    try {
+                        connection.rollback()
+                    } catch (e1: SQLException) {
+                        LOG.debug(e1.message, e)
+                    }
+
+                    LOG.error(e.message, e)
+                }
+            }
+        } catch (e: SQLException) {
+            LOG.error(e.message, e)
+        }
+
+    }
+
+    override fun findConversations(label: Label?): List<UUID> {
+        val where: String
+        if (label == null) {
+            where = "id NOT IN (SELECT message_id FROM Message_Label)"
+        } else {
+            where = "id IN (SELECT message_id FROM Message_Label WHERE label_id=" + label.id + ")"
+        }
+        val result = LinkedList<UUID>()
+        try {
+            config.connection.use { connection ->
+                connection.createStatement().use { stmt ->
+                    stmt.executeQuery(
+                        "SELECT DISTINCT conversation FROM Message WHERE " + where).use { rs ->
+                        while (rs.next()) {
+                            result.add(rs.getObject(1) as UUID)
+                        }
+                    }
+                }
+            }
+        } catch (e: SQLException) {
+            LOG.error(e.message, e)
+        }
+
+        return result
+    }
+
+    /**
+     * Replaces every occurrence of the source conversation ID with the target ID
+
+     * @param source ID of the conversation to be merged
+     * *
+     * @param target ID of the merge target
+     */
+    private fun mergeConversations(connection: Connection, source: UUID, target: UUID) {
+        try {
+            connection.prepareStatement(
+                "UPDATE Message SET conversation=? WHERE conversation=?").use { ps1 ->
+                connection.prepareStatement(
+                    "UPDATE Message_Parent SET conversation=? WHERE conversation=?").use { ps2 ->
+                    ps1.setObject(1, target)
+                    ps1.setObject(2, source)
+                    ps1.executeUpdate()
+                    ps2.setObject(1, target)
+                    ps2.setObject(2, source)
+                    ps2.executeUpdate()
+                }
+            }
+        } catch (e: SQLException) {
+            LOG.error(e.message, e)
+        }
+
+    }
+
+    companion object {
+        private val LOG = LoggerFactory.getLogger(JdbcMessageRepository::class.java)
+    }
+}
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 2af1450..c509e4a 100644
--- a/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepository.java
+++ b/repositories/src/main/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepository.java
@@ -105,9 +105,9 @@ public class JdbcProofOfWorkRepository extends JdbcHelper implements ProofOfWork
                 "nonce_trials_per_byte, extra_bytes, expiration_time, message_id) " +
                 "VALUES (?, ?, ?, ?, ?, ?, ?)")
         ) {
-            ps.setBytes(1, cryptography().getInitialHash(item.getObject()));
-            writeBlob(ps, 2, item.getObject());
-            ps.setLong(3, item.getObject().getVersion());
+            ps.setBytes(1, cryptography().getInitialHash(item.getObjectMessage()));
+            writeBlob(ps, 2, item.getObjectMessage());
+            ps.setLong(3, item.getObjectMessage().getVersion());
             ps.setLong(4, item.getNonceTrialsPerByte());
             ps.setLong(5, item.getExtraBytes());
 
@@ -120,7 +120,7 @@ public class JdbcProofOfWorkRepository extends JdbcHelper implements ProofOfWork
             }
             ps.executeUpdate();
         } catch (IOException | SQLException e) {
-            LOG.debug("Error storing object of type " + item.getObject().getPayload().getClass().getSimpleName(), e);
+            LOG.debug("Error storing object of type " + item.getObjectMessage().getPayload().getClass().getSimpleName(), e);
             throw new ApplicationException(e);
         }
     }
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.kt b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.kt
index 76031e9..1e08859 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.kt
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/JdbcProofOfWorkRepositoryTest.kt
@@ -129,7 +129,7 @@ class JdbcProofOfWorkRepositoryTest : TestBase() {
     fun `ensure item can be retrieved`() {
         val item = repo.getItem(initialHash1)
         assertThat(item, notNullValue())
-        assertThat<ObjectPayload>(item.`object`.payload, instanceOf<ObjectPayload>(GetPubkey::class.java))
+        assertThat<ObjectPayload>(item.objectMessage.payload, instanceOf<ObjectPayload>(GetPubkey::class.java))
         assertThat(item.nonceTrialsPerByte, `is`(1000L))
         assertThat(item.extraBytes, `is`(1000L))
     }
@@ -138,7 +138,7 @@ class JdbcProofOfWorkRepositoryTest : TestBase() {
     fun `ensure ack item can be retrieved`() {
         val item = repo.getItem(initialHash2)
         assertThat(item, notNullValue())
-        assertThat<ObjectPayload>(item.`object`.payload, instanceOf<ObjectPayload>(GenericPayload::class.java))
+        assertThat<ObjectPayload>(item.objectMessage.payload, instanceOf<ObjectPayload>(GenericPayload::class.java))
         assertThat(item.nonceTrialsPerByte, `is`(1000L))
         assertThat(item.extraBytes, `is`(1000L))
         assertThat(item.expirationTime, not<Number>(0))
diff --git a/repositories/src/test/java/ch/dissem/bitmessage/repository/TestBase.kt b/repositories/src/test/java/ch/dissem/bitmessage/repository/TestBase.kt
index 107e462..cbd6e76 100644
--- a/repositories/src/test/java/ch/dissem/bitmessage/repository/TestBase.kt
+++ b/repositories/src/test/java/ch/dissem/bitmessage/repository/TestBase.kt
@@ -21,16 +21,11 @@ import ch.dissem.bitmessage.ports.MultiThreadedPOWEngine
 import ch.dissem.bitmessage.utils.Singleton
 import ch.dissem.bitmessage.utils.TestUtils.mockedInternalContext
 
-/**
- * Created by chris on 20.07.15.
- */
 open class TestBase {
     companion object {
         init {
-            val security = BouncyCryptography()
-            Singleton.initialize(security)
             mockedInternalContext(
-                cryptography = security,
+                cryptography = BouncyCryptography(),
                 proofOfWorkEngine = MultiThreadedPOWEngine()
             )
         }
diff --git a/wif/build.gradle b/wif/build.gradle
index a466f69..cf317e5 100644
--- a/wif/build.gradle
+++ b/wif/build.gradle
@@ -15,5 +15,6 @@ dependencies {
     compile 'org.ini4j:ini4j:0.5.4'
     testCompile 'junit:junit:4.12'
     testCompile 'org.mockito:mockito-core:2.7.21'
+    testCompile 'com.nhaarman:mockito-kotlin:1.4.0'
     testCompile project(':cryptography-bc')
 }
diff --git a/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.java b/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.java
deleted file mode 100644
index 3f4b370..0000000
--- a/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.java
+++ /dev/null
@@ -1,106 +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.wif;
-
-import ch.dissem.bitmessage.BitmessageContext;
-import ch.dissem.bitmessage.entity.BitmessageAddress;
-import ch.dissem.bitmessage.exception.ApplicationException;
-import ch.dissem.bitmessage.utils.Base58;
-import org.ini4j.Ini;
-import org.ini4j.Profile;
-
-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.cryptography;
-
-/**
- * @author Christian Basler
- */
-public class WifExporter {
-    private final BitmessageContext ctx;
-    private final Ini ini;
-
-    public WifExporter(BitmessageContext ctx) {
-        this.ctx = ctx;
-        this.ini = new Ini();
-    }
-
-    public WifExporter addAll() {
-        for (BitmessageAddress identity : ctx.addresses().getIdentities()) {
-            addIdentity(identity);
-        }
-        return this;
-    }
-
-    public WifExporter addAll(Collection<BitmessageAddress> identities) {
-        for (BitmessageAddress identity : identities) {
-            addIdentity(identity);
-        }
-        return this;
-    }
-
-    public WifExporter addIdentity(BitmessageAddress identity) {
-        Profile.Section section = ini.add(identity.getAddress());
-        section.add("label", identity.getAlias());
-        section.add("enabled", true);
-        section.add("decoy", false);
-        if (identity.isChan()) {
-            section.add("chan", identity.isChan());
-        }
-        section.add("noncetrialsperbyte", identity.getPubkey().getNonceTrialsPerByte());
-        section.add("payloadlengthextrabytes", identity.getPubkey().getExtraBytes());
-        section.add("privsigningkey", exportSecret(identity.getPrivateKey().getPrivateSigningKey()));
-        section.add("privencryptionkey", exportSecret(identity.getPrivateKey().getPrivateEncryptionKey()));
-        return this;
-    }
-
-    private String exportSecret(byte[] privateKey) {
-        if (privateKey.length != PRIVATE_KEY_SIZE) {
-            throw new IllegalArgumentException("Private key of length 32 expected, but was " + privateKey.length);
-        }
-        byte[] result = new byte[37];
-        result[0] = (byte) 0x80;
-        System.arraycopy(privateKey, 0, result, 1, PRIVATE_KEY_SIZE);
-        byte[] hash = cryptography().doubleSha256(result, PRIVATE_KEY_SIZE + 1);
-        System.arraycopy(hash, 0, result, PRIVATE_KEY_SIZE + 1, 4);
-        return Base58.encode(result);
-    }
-
-    public void write(File file) throws IOException {
-        file.createNewFile();
-        try (FileOutputStream out = new FileOutputStream(file)) {
-            write(out);
-        }
-    }
-
-    public void write(OutputStream out) throws IOException {
-        ini.store(out);
-    }
-
-    @Override
-    public String toString() {
-        StringWriter writer = new StringWriter();
-        try {
-            ini.store(writer);
-        } catch (IOException e) {
-            throw new ApplicationException(e);
-        }
-        return writer.toString();
-    }
-}
diff --git a/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.kt b/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.kt
new file mode 100644
index 0000000..9245ba7
--- /dev/null
+++ b/wif/src/main/java/ch/dissem/bitmessage/wif/WifExporter.kt
@@ -0,0 +1,103 @@
+/*
+ * Copyright 2017 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.
+ */
+
+/*
+ * 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.wif
+
+import ch.dissem.bitmessage.BitmessageContext
+import ch.dissem.bitmessage.entity.BitmessageAddress
+import ch.dissem.bitmessage.entity.valueobject.PrivateKey.Companion.PRIVATE_KEY_SIZE
+import ch.dissem.bitmessage.utils.Base58
+import ch.dissem.bitmessage.utils.Singleton.cryptography
+import org.ini4j.Ini
+import java.io.File
+import java.io.FileOutputStream
+import java.io.OutputStream
+import java.io.StringWriter
+
+/**
+ * @author Christian Basler
+ */
+class WifExporter(private val ctx: BitmessageContext) {
+    private val ini = Ini()
+
+    fun addAll(): WifExporter {
+        ctx.addresses.getIdentities().forEach { addIdentity(it) }
+        return this
+    }
+
+    fun addAll(identities: Collection<BitmessageAddress>): WifExporter {
+        identities.forEach { addIdentity(it) }
+        return this
+    }
+
+    fun addIdentity(identity: BitmessageAddress): WifExporter {
+        val section = ini.add(identity.address)
+        section.add("label", identity.alias)
+        section.add("enabled", true)
+        section.add("decoy", false)
+        if (identity.isChan) {
+            section.add("chan", identity.isChan)
+        }
+        section.add("noncetrialsperbyte", identity.pubkey!!.nonceTrialsPerByte)
+        section.add("payloadlengthextrabytes", identity.pubkey!!.extraBytes)
+        section.add("privsigningkey", exportSecret(identity.privateKey!!.privateSigningKey))
+        section.add("privencryptionkey", exportSecret(identity.privateKey!!.privateEncryptionKey))
+        return this
+    }
+
+    private fun exportSecret(privateKey: ByteArray): String {
+        if (privateKey.size != PRIVATE_KEY_SIZE) {
+            throw IllegalArgumentException("Private key of length 32 expected, but was " + privateKey.size)
+        }
+        val result = ByteArray(37)
+        result[0] = 0x80.toByte()
+        System.arraycopy(privateKey, 0, result, 1, PRIVATE_KEY_SIZE)
+        val hash = cryptography().doubleSha256(result, PRIVATE_KEY_SIZE + 1)
+        System.arraycopy(hash, 0, result, PRIVATE_KEY_SIZE + 1, 4)
+        return Base58.encode(result)
+    }
+
+    fun write(file: File) {
+        file.createNewFile()
+        FileOutputStream(file).use { out -> write(out) }
+    }
+
+    fun write(out: OutputStream) {
+        ini.store(out)
+    }
+
+    override fun toString(): String {
+        val writer = StringWriter()
+        ini.store(writer)
+        return writer.toString()
+    }
+}
diff --git a/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.java b/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.java
deleted file mode 100644
index 0d010c9..0000000
--- a/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.java
+++ /dev/null
@@ -1,119 +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.wif;
-
-import ch.dissem.bitmessage.BitmessageContext;
-import ch.dissem.bitmessage.entity.BitmessageAddress;
-import ch.dissem.bitmessage.entity.payload.Pubkey;
-import ch.dissem.bitmessage.factory.Factory;
-import ch.dissem.bitmessage.utils.Base58;
-import org.ini4j.Ini;
-import org.ini4j.Profile;
-
-import java.io.*;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map.Entry;
-
-import static ch.dissem.bitmessage.utils.Singleton.cryptography;
-
-/**
- * @author Christian Basler
- */
-public class WifImporter {
-    private static final byte WIF_FIRST_BYTE = (byte) 0x80;
-    private static final int WIF_SECRET_LENGTH = 37;
-
-    private final BitmessageContext ctx;
-    private final List<BitmessageAddress> identities = new LinkedList<>();
-
-    public WifImporter(BitmessageContext ctx, File file) throws IOException {
-        this(ctx, new FileInputStream(file));
-    }
-
-    public WifImporter(BitmessageContext ctx, String data) throws IOException {
-        this(ctx, new ByteArrayInputStream(data.getBytes("utf-8")));
-    }
-
-    public WifImporter(BitmessageContext ctx, InputStream in, Pubkey.Feature... features) throws IOException {
-        this.ctx = ctx;
-
-        Ini ini = new Ini();
-        ini.load(in);
-
-        for (Entry<String, Profile.Section> entry : ini.entrySet()) {
-            if (!entry.getKey().startsWith("BM-"))
-                continue;
-
-            Profile.Section section = entry.getValue();
-            BitmessageAddress address = Factory.createIdentityFromPrivateKey(
-                entry.getKey(),
-                getSecret(section.get("privsigningkey")),
-                getSecret(section.get("privencryptionkey")),
-                Long.parseLong(section.get("noncetrialsperbyte")),
-                Long.parseLong(section.get("payloadlengthextrabytes")),
-                Pubkey.Feature.bitfield(features)
-            );
-            if (section.containsKey("chan")) {
-                address.setChan(Boolean.parseBoolean(section.get("chan")));
-            }
-            address.setAlias(section.get("label"));
-            identities.add(address);
-        }
-    }
-
-    private byte[] getSecret(String walletImportFormat) throws IOException {
-        byte[] bytes = Base58.decode(walletImportFormat);
-        if (bytes[0] != WIF_FIRST_BYTE)
-            throw new IOException("Unknown format: 0x80 expected as first byte, but secret " + walletImportFormat +
-                " was " + bytes[0]);
-        if (bytes.length != WIF_SECRET_LENGTH)
-            throw new IOException("Unknown format: " + WIF_SECRET_LENGTH +
-                " bytes expected, but secret " + walletImportFormat + " was " + bytes.length + " long");
-
-        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);
-        }
-        return Arrays.copyOfRange(bytes, 1, 33);
-    }
-
-    public List<BitmessageAddress> getIdentities() {
-        return identities;
-    }
-
-    public WifImporter importAll() {
-        for (BitmessageAddress identity : identities) {
-            ctx.addresses().save(identity);
-        }
-        return this;
-    }
-
-    public WifImporter importAll(Collection<BitmessageAddress> identities) {
-        for (BitmessageAddress identity : identities) {
-            ctx.addresses().save(identity);
-        }
-        return this;
-    }
-
-    public WifImporter importIdentity(BitmessageAddress identity) {
-        ctx.addresses().save(identity);
-        return this;
-    }
-}
diff --git a/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.kt b/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.kt
new file mode 100644
index 0000000..5b7e958
--- /dev/null
+++ b/wif/src/main/java/ch/dissem/bitmessage/wif/WifImporter.kt
@@ -0,0 +1,126 @@
+/*
+ * Copyright 2017 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.
+ */
+
+/*
+ * 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.wif
+
+import ch.dissem.bitmessage.BitmessageContext
+import ch.dissem.bitmessage.entity.BitmessageAddress
+import ch.dissem.bitmessage.entity.payload.Pubkey
+import ch.dissem.bitmessage.exception.ApplicationException
+import ch.dissem.bitmessage.factory.Factory
+import ch.dissem.bitmessage.utils.Base58
+import ch.dissem.bitmessage.utils.Singleton.cryptography
+import org.ini4j.Ini
+import java.io.ByteArrayInputStream
+import java.io.File
+import java.io.FileInputStream
+import java.io.InputStream
+import java.util.*
+
+/**
+ * @author Christian Basler
+ */
+class WifImporter constructor(
+    private val ctx: BitmessageContext,
+    `in`: InputStream,
+    vararg features: Pubkey.Feature
+) {
+    private val identities = LinkedList<BitmessageAddress>()
+
+    constructor(ctx: BitmessageContext, file: File) : this(ctx, FileInputStream(file))
+
+    constructor(ctx: BitmessageContext, data: String) : this(ctx, ByteArrayInputStream(data.toByteArray(charset("utf-8"))))
+
+    init {
+        val ini = Ini()
+        ini.load(`in`)
+
+        for ((key, section) in ini) {
+            if (!key.startsWith("BM-"))
+                continue
+
+            val address = Factory.createIdentityFromPrivateKey(
+                key,
+                getSecret(section["privsigningkey"] ?: throw ApplicationException("privsigningkey missing for $key")),
+                getSecret(section["privencryptionkey"] ?: throw ApplicationException("privencryptionkey missing for $key")),
+                section["noncetrialsperbyte"]?.toLongOrNull() ?: throw ApplicationException("noncetrialsperbyte missing for $key"),
+                section["payloadlengthextrabytes"]?.toLongOrNull() ?: throw ApplicationException("payloadlengthextrabytes missing for $key"),
+                Pubkey.Feature.bitfield(*features)
+            )
+            if (section.containsKey("chan")) {
+                address.isChan = java.lang.Boolean.parseBoolean(section["chan"])
+            }
+            address.alias = section["label"]
+            identities.add(address)
+        }
+    }
+
+    private fun getSecret(walletImportFormat: String): ByteArray {
+        val bytes = Base58.decode(walletImportFormat)
+        if (bytes[0] != WIF_FIRST_BYTE)
+            throw ApplicationException("Unknown format: 0x80 expected as first byte, but secret " + walletImportFormat +
+                " was " + bytes[0])
+        if (bytes.size != WIF_SECRET_LENGTH)
+            throw ApplicationException("Unknown format: " + WIF_SECRET_LENGTH +
+                " bytes expected, but secret " + walletImportFormat + " was " + bytes.size + " long")
+
+        val hash = cryptography().doubleSha256(bytes, 33)
+        (0..3)
+            .filter { hash[it] != bytes[33 + it] }
+            .forEach { throw ApplicationException("Hash check failed for secret " + walletImportFormat) }
+        return Arrays.copyOfRange(bytes, 1, 33)
+    }
+
+    fun getIdentities(): List<BitmessageAddress> {
+        return identities
+    }
+
+    fun importAll(): WifImporter {
+        identities.forEach { ctx.addresses.save(it) }
+        return this
+    }
+
+    fun importAll(identities: Collection<BitmessageAddress>): WifImporter {
+        identities.forEach { ctx.addresses.save(it) }
+        return this
+    }
+
+    fun importIdentity(identity: BitmessageAddress): WifImporter {
+        ctx.addresses.save(identity)
+        return this
+    }
+
+    companion object {
+        private const val WIF_FIRST_BYTE = 0x80.toByte()
+        private const val WIF_SECRET_LENGTH = 37
+    }
+}
diff --git a/wif/src/test/java/ch/dissem/bitmessage/wif/WifExporterTest.java b/wif/src/test/java/ch/dissem/bitmessage/wif/WifExporterTest.java
deleted file mode 100644
index d5e8bde..0000000
--- a/wif/src/test/java/ch/dissem/bitmessage/wif/WifExporterTest.java
+++ /dev/null
@@ -1,107 +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.wif;
-
-import ch.dissem.bitmessage.BitmessageContext;
-import ch.dissem.bitmessage.entity.BitmessageAddress;
-import ch.dissem.bitmessage.ports.*;
-import ch.dissem.bitmessage.cryptography.bc.BouncyCryptography;
-import org.junit.Before;
-import org.junit.Test;
-
-import static org.junit.Assert.assertEquals;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
-
-public class WifExporterTest {
-    private AddressRepository repo = mock(AddressRepository.class);
-    private BitmessageContext ctx;
-    private WifImporter importer;
-    private WifExporter exporter;
-
-    @Before
-    public void setUp() throws Exception {
-        ctx = new BitmessageContext.Builder()
-                .cryptography(BouncyCryptography.INSTANCE)
-                .networkHandler(mock(NetworkHandler.class))
-                .inventory(mock(Inventory.class))
-                .messageRepo(mock(MessageRepository.class))
-                .powRepo(mock(ProofOfWorkRepository.class))
-                .nodeRegistry(mock(NodeRegistry.class))
-                .addressRepo(repo)
-                .build();
-        importer = new WifImporter(ctx, getClass().getClassLoader().getResourceAsStream("nuked.dat"));
-        assertEquals(81, importer.getIdentities().size());
-        exporter = new WifExporter(ctx);
-    }
-
-    @Test
-    public void testAddAll() throws Exception {
-        when(repo.getIdentities()).thenReturn(importer.getIdentities());
-        exporter.addAll();
-        String result = exporter.toString();
-        int count = 0;
-        for (int i = 0; i < result.length(); i++) {
-            if (result.charAt(i) == '[') count++;
-        }
-        assertEquals(importer.getIdentities().size(), count);
-    }
-
-    @Test
-    public void testAddAllFromCollection() throws Exception {
-        exporter.addAll(importer.getIdentities());
-        String result = exporter.toString();
-        int count = 0;
-        for (int i = 0; i < result.length(); i++) {
-            if (result.charAt(i) == '[') count++;
-        }
-        assertEquals(importer.getIdentities().size(), count);
-    }
-
-    @Test
-    public void testAddIdentity() throws Exception {
-        String expected = "[BM-2DAjcCFrqFrp88FUxExhJ9kPqHdunQmiyn]" + System.lineSeparator() +
-                "label = Nuked Address" + System.lineSeparator() +
-                "enabled = true" + System.lineSeparator() +
-                "decoy = false" + System.lineSeparator() +
-                "noncetrialsperbyte = 320" + System.lineSeparator() +
-                "payloadlengthextrabytes = 14000" + System.lineSeparator() +
-                "privsigningkey = 5KU2gbe9u4rKJ8PHYb1rvwMnZnAJj4gtV5GLwoYckeYzygWUzB9" + System.lineSeparator() +
-                "privencryptionkey = 5KHd4c6cavd8xv4kzo3PwnVaYuBgEfg7voPQ5V97aZKgpYBXGck" + System.lineSeparator() +
-                System.lineSeparator();
-        importer = new WifImporter(ctx, expected);
-        exporter.addIdentity(importer.getIdentities().get(0));
-        assertEquals(expected, exporter.toString());
-    }
-
-    @Test
-    public void ensureChanIsAdded() throws Exception {
-        String expected = "[BM-2cW67GEKkHGonXKZLCzouLLxnLym3azS8r]" + System.lineSeparator() +
-                "label = general" + System.lineSeparator() +
-                "enabled = true" + System.lineSeparator() +
-                "decoy = false" + System.lineSeparator() +
-                "chan = true" + System.lineSeparator() +
-                "noncetrialsperbyte = 1000" + System.lineSeparator() +
-                "payloadlengthextrabytes = 1000" + System.lineSeparator() +
-                "privsigningkey = 5Jnbdwc4u4DG9ipJxYLznXSvemkRFueQJNHujAQamtDDoX3N1eQ" + System.lineSeparator() +
-                "privencryptionkey = 5JrDcFtQDv5ydcHRW6dfGUEvThoxCCLNEUaxQfy8LXXgTJzVAcq" + System.lineSeparator() +
-                System.lineSeparator();
-        BitmessageAddress chan = ctx.joinChan("general", "BM-2cW67GEKkHGonXKZLCzouLLxnLym3azS8r");
-        exporter.addIdentity(chan);
-        assertEquals(expected, exporter.toString());
-    }
-}
diff --git a/wif/src/test/java/ch/dissem/bitmessage/wif/WifExporterTest.kt b/wif/src/test/java/ch/dissem/bitmessage/wif/WifExporterTest.kt
new file mode 100644
index 0000000..657ec48
--- /dev/null
+++ b/wif/src/test/java/ch/dissem/bitmessage/wif/WifExporterTest.kt
@@ -0,0 +1,122 @@
+/*
+ * Copyright 2017 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.
+ */
+
+/*
+ * 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.wif
+
+import ch.dissem.bitmessage.BitmessageContext
+import ch.dissem.bitmessage.cryptography.bc.BouncyCryptography
+import ch.dissem.bitmessage.ports.AddressRepository
+import com.nhaarman.mockito_kotlin.mock
+import com.nhaarman.mockito_kotlin.whenever
+import org.junit.Assert.assertEquals
+import org.junit.Before
+import org.junit.Test
+
+class WifExporterTest {
+    private val repo = mock<AddressRepository>()
+    private lateinit var ctx: BitmessageContext
+    private lateinit var importer: WifImporter
+    private lateinit var exporter: WifExporter
+
+    @Before
+    fun setUp() {
+        ctx = BitmessageContext.Builder()
+            .cryptography(BouncyCryptography())
+            .networkHandler(mock())
+            .inventory(mock())
+            .messageRepo(mock())
+            .powRepo(mock())
+            .nodeRegistry(mock())
+            .addressRepo(repo)
+            .listener { }
+            .build()
+        importer = WifImporter(ctx, javaClass.classLoader.getResourceAsStream("nuked.dat"))
+        assertEquals(81, importer.getIdentities().size)
+        exporter = WifExporter(ctx)
+    }
+
+    @Test
+    fun `ensure all identities in context are added`() {
+        whenever(repo.getIdentities()).thenReturn(importer.getIdentities())
+        exporter.addAll()
+        val result = exporter.toString()
+        var count = 0
+        for (i in 0..result.length - 1) {
+            if (result[i] == '[') count++
+        }
+        assertEquals(importer.getIdentities().size, count)
+    }
+
+    @Test
+    fun `ensure all from a collection are added`() {
+        exporter.addAll(importer.getIdentities())
+        val result = exporter.toString()
+        var count = 0
+        for (i in 0..result.length - 1) {
+            if (result[i] == '[') count++
+        }
+        assertEquals(importer.getIdentities().size, count)
+    }
+
+    @Test
+    fun `ensure identity is added`() {
+        val expected = "[BM-2DAjcCFrqFrp88FUxExhJ9kPqHdunQmiyn]" + System.lineSeparator() +
+            "label = Nuked Address" + System.lineSeparator() +
+            "enabled = true" + System.lineSeparator() +
+            "decoy = false" + System.lineSeparator() +
+            "noncetrialsperbyte = 320" + System.lineSeparator() +
+            "payloadlengthextrabytes = 14000" + System.lineSeparator() +
+            "privsigningkey = 5KU2gbe9u4rKJ8PHYb1rvwMnZnAJj4gtV5GLwoYckeYzygWUzB9" + System.lineSeparator() +
+            "privencryptionkey = 5KHd4c6cavd8xv4kzo3PwnVaYuBgEfg7voPQ5V97aZKgpYBXGck" + System.lineSeparator() +
+            System.lineSeparator()
+        importer = WifImporter(ctx, expected)
+        exporter.addIdentity(importer.getIdentities()[0])
+        assertEquals(expected, exporter.toString())
+    }
+
+    @Test
+    fun `ensure chan is added`() {
+        val expected = "[BM-2cW67GEKkHGonXKZLCzouLLxnLym3azS8r]" + System.lineSeparator() +
+            "label = general" + System.lineSeparator() +
+            "enabled = true" + System.lineSeparator() +
+            "decoy = false" + System.lineSeparator() +
+            "chan = true" + System.lineSeparator() +
+            "noncetrialsperbyte = 1000" + System.lineSeparator() +
+            "payloadlengthextrabytes = 1000" + System.lineSeparator() +
+            "privsigningkey = 5Jnbdwc4u4DG9ipJxYLznXSvemkRFueQJNHujAQamtDDoX3N1eQ" + System.lineSeparator() +
+            "privencryptionkey = 5JrDcFtQDv5ydcHRW6dfGUEvThoxCCLNEUaxQfy8LXXgTJzVAcq" + System.lineSeparator() +
+            System.lineSeparator()
+        val chan = ctx.joinChan("general", "BM-2cW67GEKkHGonXKZLCzouLLxnLym3azS8r")
+        exporter.addIdentity(chan)
+        assertEquals(expected, exporter.toString())
+    }
+}
diff --git a/wif/src/test/java/ch/dissem/bitmessage/wif/WifImporterTest.java b/wif/src/test/java/ch/dissem/bitmessage/wif/WifImporterTest.java
deleted file mode 100644
index 2116b3a..0000000
--- a/wif/src/test/java/ch/dissem/bitmessage/wif/WifImporterTest.java
+++ /dev/null
@@ -1,116 +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.wif;
-
-import ch.dissem.bitmessage.BitmessageContext;
-import ch.dissem.bitmessage.entity.BitmessageAddress;
-import ch.dissem.bitmessage.ports.*;
-import ch.dissem.bitmessage.cryptography.bc.BouncyCryptography;
-import org.junit.Before;
-import org.junit.Test;
-
-import java.util.List;
-
-import static org.junit.Assert.*;
-import static org.mockito.Mockito.*;
-
-public class WifImporterTest {
-    private AddressRepository repo = mock(AddressRepository.class);
-    private BitmessageContext ctx;
-    private WifImporter importer;
-
-    @Before
-    public void setUp() throws Exception {
-        ctx = new BitmessageContext.Builder()
-                .cryptography(BouncyCryptography.INSTANCE)
-                .networkHandler(mock(NetworkHandler.class))
-                .inventory(mock(Inventory.class))
-                .messageRepo(mock(MessageRepository.class))
-                .powRepo(mock(ProofOfWorkRepository.class))
-                .nodeRegistry(mock(NodeRegistry.class))
-                .addressRepo(repo)
-                .build();
-        importer = new WifImporter(ctx, getClass().getClassLoader().getResourceAsStream("nuked.dat"));
-    }
-
-
-    @Test
-    public void testImportSingleIdentity() throws Exception {
-        importer = new WifImporter(ctx, "[BM-2cWJ4UFRTCehWuWNsW8fJkAYMxU4S8jxci]\n" +
-                "label = Nuked Address\n" +
-                "enabled = true\n" +
-                "decoy = false\n" +
-                "noncetrialsperbyte = 320\n" +
-                "payloadlengthextrabytes = 14000\n" +
-                "privsigningkey = 5JU5t2JA58sP5aJwKAcrYg5EpBA9bJPrBSaFfaZ7ogmwTMDCfHL\n" +
-                "privencryptionkey = 5Kkx5MwjQcM4kyduKvCEPM6nVNynMdRcg88VQ5iVDWUekMz1igH");
-        assertEquals(1, importer.getIdentities().size());
-        BitmessageAddress identity = importer.getIdentities().get(0);
-        assertEquals("BM-2cWJ4UFRTCehWuWNsW8fJkAYMxU4S8jxci", identity.getAddress());
-        assertEquals("Nuked Address", identity.getAlias());
-        assertEquals(320, identity.getPubkey().getNonceTrialsPerByte());
-        assertEquals(14000, identity.getPubkey().getExtraBytes());
-        assertNotNull("Private key", identity.getPrivateKey());
-        assertEquals(32, identity.getPrivateKey().getPrivateEncryptionKey().length);
-        assertEquals(32, identity.getPrivateKey().getPrivateSigningKey().length);
-        assertFalse(identity.isChan());
-    }
-
-    @Test
-    public void testGetIdentities() throws Exception {
-        List<BitmessageAddress> identities = importer.getIdentities();
-        assertEquals(81, identities.size());
-    }
-
-    @Test
-    public void testImportAll() throws Exception {
-        importer.importAll();
-        verify(repo, times(81)).save(any(BitmessageAddress.class));
-    }
-
-    @Test
-    public void testImportAllFromCollection() throws Exception {
-        List<BitmessageAddress> identities = importer.getIdentities();
-        importer.importAll(identities);
-        for (BitmessageAddress identity : identities) {
-            verify(repo, times(1)).save(identity);
-        }
-    }
-
-    @Test
-    public void testImportIdentity() throws Exception {
-        List<BitmessageAddress> identities = importer.getIdentities();
-        importer.importIdentity(identities.get(0));
-        verify(repo, times(1)).save(identities.get(0));
-    }
-
-    @Test
-    public void ensureChanIsImported() throws Exception {
-        importer = new WifImporter(ctx, "[BM-2cW67GEKkHGonXKZLCzouLLxnLym3azS8r]\n" +
-                "label = [chan] general\n" +
-                "enabled = true\n" +
-                "decoy = false\n" +
-                "chan = true\n" +
-                "noncetrialsperbyte = 1000\n" +
-                "payloadlengthextrabytes = 1000\n" +
-                "privsigningkey = 5Jnbdwc4u4DG9ipJxYLznXSvemkRFueQJNHujAQamtDDoX3N1eQ\n" +
-                "privencryptionkey = 5JrDcFtQDv5ydcHRW6dfGUEvThoxCCLNEUaxQfy8LXXgTJzVAcq\n");
-        assertEquals(1, importer.getIdentities().size());
-        BitmessageAddress chan = importer.getIdentities().get(0);
-        assertTrue(chan.isChan());
-    }
-}
diff --git a/wif/src/test/java/ch/dissem/bitmessage/wif/WifImporterTest.kt b/wif/src/test/java/ch/dissem/bitmessage/wif/WifImporterTest.kt
new file mode 100644
index 0000000..08b14fa
--- /dev/null
+++ b/wif/src/test/java/ch/dissem/bitmessage/wif/WifImporterTest.kt
@@ -0,0 +1,132 @@
+/*
+ * Copyright 2017 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.
+ */
+
+/*
+ * 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.wif
+
+import ch.dissem.bitmessage.BitmessageContext
+import ch.dissem.bitmessage.cryptography.bc.BouncyCryptography
+import ch.dissem.bitmessage.ports.AddressRepository
+import com.nhaarman.mockito_kotlin.any
+import com.nhaarman.mockito_kotlin.mock
+import com.nhaarman.mockito_kotlin.times
+import com.nhaarman.mockito_kotlin.verify
+import org.junit.Assert.*
+import org.junit.Before
+import org.junit.Test
+
+class WifImporterTest {
+    private val repo = mock<AddressRepository>()
+    private lateinit var ctx: BitmessageContext
+    private lateinit var importer: WifImporter
+
+    @Before
+    fun setUp() {
+        ctx = BitmessageContext.Builder()
+            .cryptography(BouncyCryptography())
+            .networkHandler(mock())
+            .inventory(mock())
+            .messageRepo(mock())
+            .powRepo(mock())
+            .nodeRegistry(mock())
+            .addressRepo(repo)
+            .listener { }
+            .build()
+        importer = WifImporter(ctx, javaClass.classLoader.getResourceAsStream("nuked.dat"))
+    }
+
+
+    @Test
+    fun `ensure single identity is imported`() {
+        importer = WifImporter(ctx, "[BM-2cWJ4UFRTCehWuWNsW8fJkAYMxU4S8jxci]\n" +
+            "label = Nuked Address\n" +
+            "enabled = true\n" +
+            "decoy = false\n" +
+            "noncetrialsperbyte = 320\n" +
+            "payloadlengthextrabytes = 14000\n" +
+            "privsigningkey = 5JU5t2JA58sP5aJwKAcrYg5EpBA9bJPrBSaFfaZ7ogmwTMDCfHL\n" +
+            "privencryptionkey = 5Kkx5MwjQcM4kyduKvCEPM6nVNynMdRcg88VQ5iVDWUekMz1igH")
+        assertEquals(1, importer.getIdentities().size)
+        val identity = importer.getIdentities()[0]
+        assertEquals("BM-2cWJ4UFRTCehWuWNsW8fJkAYMxU4S8jxci", identity.address)
+        assertEquals("Nuked Address", identity.alias)
+        assertEquals(320L, identity.pubkey?.nonceTrialsPerByte)
+        assertEquals(14000L, identity.pubkey?.extraBytes)
+        assertNotNull("Private key", identity.privateKey)
+        assertEquals(32, identity.privateKey?.privateEncryptionKey?.size)
+        assertEquals(32, identity.privateKey?.privateSigningKey?.size)
+        assertFalse(identity.isChan)
+    }
+
+    @Test
+    fun `ensure all identities are retrieved`() {
+        val identities = importer.getIdentities()
+        assertEquals(81, identities.size)
+    }
+
+    @Test
+    fun `ensure all identities are imported`() {
+        importer.importAll()
+        verify(repo, times(81)).save(any())
+    }
+
+    @Test
+    fun `ensure all identities in collection are imported`() {
+        val identities = importer.getIdentities()
+        importer.importAll(identities)
+        for (identity in identities) {
+            verify(repo, times(1)).save(identity)
+        }
+    }
+
+    @Test
+    fun `ensure single identity from list is imported`() {
+        val identities = importer.getIdentities()
+        importer.importIdentity(identities[0])
+        verify(repo, times(1)).save(identities[0])
+    }
+
+    @Test
+    fun `ensure chan is imported`() {
+        importer = WifImporter(ctx, "[BM-2cW67GEKkHGonXKZLCzouLLxnLym3azS8r]\n" +
+            "label = [chan] general\n" +
+            "enabled = true\n" +
+            "decoy = false\n" +
+            "chan = true\n" +
+            "noncetrialsperbyte = 1000\n" +
+            "payloadlengthextrabytes = 1000\n" +
+            "privsigningkey = 5Jnbdwc4u4DG9ipJxYLznXSvemkRFueQJNHujAQamtDDoX3N1eQ\n" +
+            "privencryptionkey = 5JrDcFtQDv5ydcHRW6dfGUEvThoxCCLNEUaxQfy8LXXgTJzVAcq\n")
+        assertEquals(1, importer.getIdentities().size)
+        val chan = importer.getIdentities()[0]
+        assertTrue(chan.isChan)
+    }
+}