diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index c7783cd..7f6f5fa 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -42,7 +42,7 @@
                 android:value=".activities.MainActivity" />
         </activity>
 
-        <service android:name=".bluetooth.ChatService" />
+        <service android:name=".protocol.ChatService" />
 
     </application>
 
diff --git a/app/src/main/scala/com/nutomic/ensichat/activities/AddContactsActivity.scala b/app/src/main/scala/com/nutomic/ensichat/activities/AddContactsActivity.scala
index 159085d..56adb42 100644
--- a/app/src/main/scala/com/nutomic/ensichat/activities/AddContactsActivity.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/activities/AddContactsActivity.scala
@@ -10,10 +10,8 @@ import android.view._
 import android.widget.AdapterView.OnItemClickListener
 import android.widget._
 import com.nutomic.ensichat.R
-import com.nutomic.ensichat.bluetooth.ChatService
-import com.nutomic.ensichat.bluetooth.ChatService.OnMessageReceivedListener
 import com.nutomic.ensichat.protocol.messages.{Message, RequestAddContact, ResultAddContact}
-import com.nutomic.ensichat.protocol.{Address, Crypto}
+import com.nutomic.ensichat.protocol.{Address, ChatService, Crypto}
 import com.nutomic.ensichat.util.{DevicesAdapter, IdenticonGenerator}
 
 import scala.collection.SortedSet
@@ -23,14 +21,14 @@ import scala.collection.SortedSet
  *
  * Adding a contact requires confirmation on both sides.
  */
-class AddContactsActivity extends EnsiChatActivity with ChatService.OnNearbyContactsChangedListener
-  with OnItemClickListener with OnMessageReceivedListener {
+class AddContactsActivity extends EnsiChatActivity with ChatService.OnConnectionsChangedListener
+  with OnItemClickListener with ChatService.OnMessageReceivedListener {
 
   private val Tag = "AddContactsActivity"
 
   private lazy val Adapter = new DevicesAdapter(this)
 
-  private lazy val Database = service.database
+  private lazy val Database = service.Database
 
   private lazy val Crypto = new Crypto(this)
 
@@ -46,8 +44,7 @@ class AddContactsActivity extends EnsiChatActivity with ChatService.OnNearbyCont
    * @param localConfirmed If true, the local user has accepted adding the contact.
    * @param remoteConfirmed If true, the remote contact has accepted adding this device as contact.
    */
-  private class AddContactInfo(val localConfirmed: Boolean, val remoteConfirmed: Boolean) {
-  }
+  private class AddContactInfo(val localConfirmed: Boolean, val remoteConfirmed: Boolean)
 
   /**
    * Initializes layout, registers connection and message listeners.
@@ -71,7 +68,7 @@ class AddContactsActivity extends EnsiChatActivity with ChatService.OnNearbyCont
   /**
    * Displays newly connected devices in the list.
    */
-  override def onNearbyContactsChanged(devices: Set[Address]): Unit = {
+  override def onConnectionsChanged(devices: Set[Address]): Unit = {
     runOnUiThread(new Runnable {
       override def run(): Unit  = {
         Adapter.clear()
diff --git a/app/src/main/scala/com/nutomic/ensichat/activities/EnsiChatActivity.scala b/app/src/main/scala/com/nutomic/ensichat/activities/EnsiChatActivity.scala
index 499051f..867192f 100644
--- a/app/src/main/scala/com/nutomic/ensichat/activities/EnsiChatActivity.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/activities/EnsiChatActivity.scala
@@ -3,7 +3,8 @@ package com.nutomic.ensichat.activities
 import android.app.Activity
 import android.content.{ComponentName, Context, Intent, ServiceConnection}
 import android.os.{Bundle, IBinder}
-import com.nutomic.ensichat.bluetooth.{ChatService, ChatServiceBinder}
+import com.nutomic.ensichat.protocol.ChatService
+import com.nutomic.ensichat.protocol.ChatServiceBinder
 
 /**
  * Connects to [[ChatService]] and provides access to it.
diff --git a/app/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala b/app/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala
new file mode 100644
index 0000000..9763477
--- /dev/null
+++ b/app/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala
@@ -0,0 +1,198 @@
+package com.nutomic.ensichat.bluetooth
+
+import java.util.UUID
+
+import android.bluetooth.{BluetoothAdapter, BluetoothDevice, BluetoothSocket}
+import android.content.{BroadcastReceiver, Context, Intent, IntentFilter}
+import android.preference.PreferenceManager
+import android.util.Log
+import com.google.common.collect.HashBiMap
+import com.nutomic.ensichat.R
+import com.nutomic.ensichat.protocol.ChatService.InterfaceHandler
+import com.nutomic.ensichat.protocol._
+import com.nutomic.ensichat.protocol.messages.{ConnectionInfo, Message}
+
+import scala.collection.immutable.HashMap
+
+object BluetoothInterface {
+
+  /**
+   * Bluetooth service UUID version 5, created with namespace URL and "ensichat.nutomic.com".
+   */
+  val AppUuid: UUID = UUID.fromString("8ed52b7a-4501-5348-b054-3d94d004656e")
+
+}
+
+/**
+ * Handles all Bluetooth connectivity.
+ */
+class BluetoothInterface(Service: ChatService, Crypto: Crypto) extends InterfaceHandler {
+
+  private val Tag = "BluetoothInterface"
+
+  private lazy val BtAdapter = BluetoothAdapter.getDefaultAdapter
+
+  private var devices = new HashMap[Device.ID, Device]()
+
+  private var connections = new HashMap[Device.ID, TransferThread]()
+
+  private lazy val ListenThread =
+    new ListenThread(Service.getString(R.string.app_name), BtAdapter, onConnectionOpened)
+
+  private var cancelDiscovery = false
+
+  private var discovered = Set[Device]()
+
+  private val AddressDeviceMap = HashBiMap.create[Address, Device.ID]()
+
+  /**
+   * Initializes and starts discovery and listening.
+   */
+  override def create(): Unit = {
+    Service.registerReceiver(DeviceDiscoveredReceiver,
+      new IntentFilter(BluetoothDevice.ACTION_FOUND))
+    Service.registerReceiver(BluetoothStateReceiver,
+      new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED))
+    Service.registerReceiver(DiscoveryFinishedReceiver,
+      new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED))
+    startBluetoothConnections()
+  }
+
+  /**
+   * Stops discovery and listening.
+   */
+  override def destroy(): Unit = {
+    ListenThread.cancel()
+    cancelDiscovery = true
+    Service.unregisterReceiver(DeviceDiscoveredReceiver)
+    Service.unregisterReceiver(BluetoothStateReceiver)
+    Service.unregisterReceiver(DiscoveryFinishedReceiver)
+  }
+
+  /**
+   * Starts discovery and listening.
+   */
+  private def startBluetoothConnections(): Unit = {
+    ListenThread.start()
+    cancelDiscovery = false
+    discover()
+  }
+
+  /**
+   * Runs discovery as long as [[cancelDiscovery]] is false.
+   */
+  def discover(): Unit = {
+    if (cancelDiscovery)
+      return
+
+    if (!BtAdapter.isDiscovering) {
+      Log.v(Tag, "Starting discovery")
+      BtAdapter.startDiscovery()
+    }
+
+    val scanInterval = PreferenceManager.getDefaultSharedPreferences(Service)
+      .getString("scan_interval_seconds", "15").toInt * 1000
+    Service.MainHandler.postDelayed(new Runnable {
+      override def run(): Unit = discover()
+    }, scanInterval)
+  }
+
+  /**
+   * Stores newly discovered devices.
+   */
+  private val DeviceDiscoveredReceiver = new BroadcastReceiver() {
+    override def onReceive(context: Context, intent: Intent) {
+      discovered += new Device(intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE), false)
+    }
+  }
+
+  /**
+   * Initiates connection to discovered devices.
+   */
+  private val DiscoveryFinishedReceiver = new BroadcastReceiver() {
+    override def onReceive(context: Context, intent: Intent): Unit = {
+      discovered.filterNot(d => connections.keySet.contains(d.Id))
+        .foreach { d =>
+        new ConnectThread(d, onConnectionOpened).start()
+        devices += (d.Id -> d)
+      }
+      discovered = Set[Device]()
+    }
+  }
+
+  /**
+   * Starts or stops listening and discovery based on bluetooth state.
+   */
+  private val BluetoothStateReceiver = new BroadcastReceiver {
+    override def onReceive(context: Context, intent: Intent): Unit = {
+      intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1) match {
+        case BluetoothAdapter.STATE_ON =>
+          if (Crypto.localKeysExist)
+            startBluetoothConnections()
+        case BluetoothAdapter.STATE_TURNING_OFF =>
+          Log.i(Tag, "Bluetooth disabled, stopping connectivity")
+          ListenThread.cancel()
+          cancelDiscovery = true
+          connections.foreach(_._2.close())
+        case _ =>
+      }
+    }
+  }
+
+
+  /**
+   * Initiates data transfer with device.
+   */
+  def onConnectionOpened(device: Device, socket: BluetoothSocket): Unit = {
+    devices += (device.Id -> device)
+    connections += (device.Id ->
+      new TransferThread(device, socket, this, Crypto, onReceiveMessage))
+    connections(device.Id).start()
+  }
+
+  /**
+   * Removes device from active connections.
+   */
+  def onConnectionClosed(device: Device, socket: BluetoothSocket): Unit = {
+    devices -= device.Id
+    connections -= device.Id
+    val inv = AddressDeviceMap.inverse()
+    Service.callConnectionListeners()
+    inv.remove(device.Id)
+  }
+
+  /**
+   * Passes incoming messages to [[ChatService]].
+   *
+   * Also uses [[ConnectionInfo]] message to determine mapping from [[Device.ID]] to [[Address]].
+   *
+   * @param msg The message that was received.
+   * @param device Device that sent the message.
+   */
+  private def onReceiveMessage(msg: Message, device: Device.ID): Unit = msg.Body match {
+    case info: ConnectionInfo =>
+      val sender = Service.onConnectionOpened(msg)
+      sender match {
+        case Some(s) =>
+          AddressDeviceMap.put(Crypto.calculateAddress(info.key), device)
+          Service.callConnectionListeners()
+        case None =>
+      }
+    case _ =>
+      Service.onMessageReceived(msg)
+  }
+
+  /**
+   * Sends the message to the target address specified in the message header.
+   */
+  override def send(msg: Message): Unit = {
+    connections.apply(AddressDeviceMap.get(msg.Header.Target)).send(msg)
+  }
+
+  /**
+   * Returns all active Bluetooth connections.
+   */
+  def getConnections: Set[Address] =
+    connections.map(x => AddressDeviceMap.inverse().get(x._1)).toSet
+
+}
diff --git a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ChatService.scala b/app/src/main/scala/com/nutomic/ensichat/bluetooth/ChatService.scala
deleted file mode 100644
index 28022ce..0000000
--- a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ChatService.scala
+++ /dev/null
@@ -1,333 +0,0 @@
-package com.nutomic.ensichat.bluetooth
-
-import java.util.UUID
-
-import android.app.Service
-import android.bluetooth.{BluetoothAdapter, BluetoothDevice, BluetoothSocket}
-import android.content.{BroadcastReceiver, Context, Intent, IntentFilter}
-import android.os.Handler
-import android.preference.PreferenceManager
-import android.util.Log
-import com.google.common.collect.HashBiMap
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.bluetooth.ChatService.{OnMessageReceivedListener, OnNearbyContactsChangedListener}
-import com.nutomic.ensichat.protocol._
-import com.nutomic.ensichat.protocol.messages.{ConnectionInfo, Message, MessageBody, MessageHeader}
-import com.nutomic.ensichat.util.Database
-
-import scala.collection.SortedSet
-import scala.collection.immutable.{HashMap, HashSet, TreeSet}
-import scala.concurrent.Future
-import scala.concurrent.ExecutionContext.Implicits.global
-import scala.ref.WeakReference
-
-object ChatService {
-
-  /**
-   * Bluetooth service UUID version 5, created with namespace URL and "ensichat.nutomic.com".
-   */
-  val appUuid: UUID = UUID.fromString("8ed52b7a-4501-5348-b054-3d94d004656e")
-
-  /**
-   * Used with [[ChatService.registerConnectionListener]], called when a bluetooth device
-   * connects or disconnects
-   */
-  trait OnNearbyContactsChangedListener {
-    def onNearbyContactsChanged(devices: Set[Address]): Unit
-  }
-
-  trait OnMessageReceivedListener {
-    def onMessageReceived(messages: SortedSet[Message]): Unit
-  }
-
-}
-
-/**
- * Handles all Bluetooth connectivity.
- */
-class ChatService extends Service {
-
-  private val Tag = "ChatService"
-
-  private val Binder = new ChatServiceBinder(this)
-
-  private var bluetoothAdapter: BluetoothAdapter = _
-
-  /**
-   * For this (and [[messageListeners]], functions would be useful instead of instances,
-   * but on a Nexus S (Android 4.1.2), these functions are garbage collected even when
-   * referenced.
-   */
-  private var connectionListeners = new HashSet[WeakReference[OnNearbyContactsChangedListener]]()
-
-  private var messageListeners = Set[WeakReference[OnMessageReceivedListener]]()
-
-  private var devices = new HashMap[Device.ID, Device]()
-
-  private var connections = new HashMap[Device.ID, TransferThread]()
-
-  private var ListenThread: ListenThread = _
-
-  private var cancelDiscovery = false
-
-  private val MainHandler = new Handler()
-
-  private lazy val Database = new Database(this)
-
-  private lazy val Crypto = new Crypto(this)
-
-  private var discovered = Set[Device]()
-
-  private val AddressDeviceMap = HashBiMap.create[Address, Device.ID]()
-
-  /**
-   * Sets up bluetooth connectivity.
-   */
-  override def onCreate(): Unit = {
-    super.onCreate()
-
-    bluetoothAdapter = BluetoothAdapter.getDefaultAdapter
-
-    registerReceiver(DeviceDiscoveredReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND))
-    registerReceiver(BluetoothStateReceiver, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED))
-    registerReceiver(DiscoveryFinishedReceiver,
-      new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED))
-
-    Future {
-      Crypto.generateLocalKeys()
-      startBluetoothConnections()
-      Log.i(Tag, "Service started, address is " + Crypto.getLocalAddress)
-    }
-  }
-
-  override def onStartCommand(intent: Intent, flags: Int, startId: Int) = Service.START_STICKY
-
-  override def onBind(intent: Intent) =  Binder
-
-  /**
-   * Stops discovery, listening and unregisters receivers.
-   */
-  override def onDestroy(): Unit = {
-    super.onDestroy()
-    ListenThread.cancel()
-    cancelDiscovery = true
-    unregisterReceiver(DeviceDiscoveredReceiver)
-    unregisterReceiver(BluetoothStateReceiver)
-    unregisterReceiver(DiscoveryFinishedReceiver)
-  }
-
-  /**
-   * Stops any current discovery, then starts a new one, recursively until service is stopped.
-   */
-  def discover(): Unit = {
-    if (cancelDiscovery)
-      return
-
-    if (!bluetoothAdapter.isDiscovering) {
-      Log.v(Tag, "Starting discovery")
-      bluetoothAdapter.startDiscovery()
-    }
-
-    val scanInterval = PreferenceManager.getDefaultSharedPreferences(this)
-      .getString("scan_interval_seconds", "15").toInt * 1000
-    MainHandler.postDelayed(new Runnable {
-      override def run(): Unit = discover()
-    }, scanInterval)
-  }
-
-  /**
-   * Receives newly discovered devices and connects to them.
-   */
-  private val DeviceDiscoveredReceiver = new BroadcastReceiver() {
-    override def onReceive(context: Context, intent: Intent) {
-      discovered += new Device(intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE), false)
-    }
-  }
-
-  /**
-   * Iniates the actual connection to discovered devices.
-   */
-  private val DiscoveryFinishedReceiver = new BroadcastReceiver() {
-    override def onReceive(context: Context, intent: Intent): Unit = {
-      discovered.filterNot(d => connections.keySet.contains(d.Id))
-        .foreach { d =>
-        new ConnectThread(d, onConnectionChanged).start()
-        devices += (d.Id -> d)
-      }
-      discovered = Set[Device]()
-    }
-  }
-
-  /**
-   * Starts or stops listening and discovery based on bluetooth state.
-   */
-  private val BluetoothStateReceiver = new BroadcastReceiver {
-    override def onReceive(context: Context, intent: Intent): Unit = {
-      intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1) match {
-        case BluetoothAdapter.STATE_ON =>
-          if (Crypto.localKeysExist)
-            startBluetoothConnections()
-        case BluetoothAdapter.STATE_TURNING_OFF =>
-          connections.foreach(d => d._2.close())
-        case BluetoothAdapter.STATE_OFF =>
-          Log.i(Tag, "Bluetooth disabled, stopping listening and discovery")
-          if (ListenThread != null) {
-            ListenThread.cancel()
-          }
-          cancelDiscovery = true
-        case _ =>
-      }
-    }
-  }
-
-  /**
-   * Starts to listen for incoming connections, and starts regular active discovery.
-   */
-  private def startBluetoothConnections(): Unit = {
-    cancelDiscovery = false
-    discover()
-    ListenThread =
-      new ListenThread(getString(R.string.app_name), bluetoothAdapter, onConnectionChanged)
-    ListenThread.start()
-  }
-
-  /**
-   * Registers a listener that is called whenever a new device is connected.
-   */
-  def registerConnectionListener(listener: OnNearbyContactsChangedListener): Unit = {
-    connectionListeners += new WeakReference[OnNearbyContactsChangedListener](listener)
-    nearbyContactsChanged(listener)
-  }
-
-  /**
-   * Called when a Bluetooth device is connected.
-   *
-   * Adds the device to [[connections]], notifies all [[connectionListeners]], sends DeviceInfoMessage.
-   *
-   * @param device The updated device info for the remote device.
-   * @param socket A socket for data transfer if device.connected is true, otherwise null.
-   */
-  def onConnectionChanged(device: Device, socket: BluetoothSocket): Unit = {
-    devices += (device.Id -> device)
-
-    if (device.Connected && !connections.keySet.contains(device.Id)) {
-      connections += (device.Id ->
-        new TransferThread(device, socket, this, Crypto, onReceiveMessage))
-      connections(device.Id).start()
-    } else {
-      Log.i(Tag, device + " has disconnected")
-      AddressDeviceMap.inverse().remove(device.Id)
-    }
-  }
-
-  /**
-   * Calls listener with [[devices]] (converting [[Device.ID]]s to [[Address]]es.
-   */
-  def nearbyContactsChanged(listener: OnNearbyContactsChangedListener) = {
-    listener.onNearbyContactsChanged(
-      devices.keySet.map(d => AddressDeviceMap.inverse().get(d)).filter(_ != null))
-  }
-
-  /**
-   * Sends a new message to the given target address.
-   */
-  def sendTo(target: Address, body: MessageBody): Unit = {
-    if (!AddressDeviceMap.containsKey(target)) {
-      Log.w(Tag, "Receiver " + target + " is not connected, ignoring message")
-      return
-    }
-
-    val header = new MessageHeader(body.Type, MessageHeader.DefaultHopLimit,
-      Crypto.getLocalAddress, target, 0, 0)
-
-    val msg = new Message(header, body)
-    val encrypted = Crypto.encrypt(Crypto.sign(msg))
-    connections.apply(AddressDeviceMap.get(target)).send(encrypted)
-    Database.addMessage(msg)
-    callMessageReceivedListeners(msg)
-  }
-
-  /**
-   * Saves the message to database and sends it to registered listeners.
-   *
-   * If you want to send a new message, use [[sendTo]].
-   *
-   * Messages must always be sent between local device and a contact.
-   *
-   * NOTE: Messages sent from the local node using [[sendTo]] are also passed through this method.
-   */
-  private def onReceiveMessage(message: Message, device: Device.ID): Unit = {
-    assert(message.Header.Origin != Crypto.getLocalAddress)
-
-    message.Body match {
-      case info: ConnectionInfo =>
-        if (message.Header.Origin == Crypto.getLocalAddress)
-          return
-        onNeighborConnected(info, device)
-      case _ =>
-        val decrypted = Crypto.decrypt(message)
-        if (!Crypto.verify(decrypted)) {
-          Log.i(Tag, "Dropping message with invalid signature from " + message.Header.Origin)
-          return
-        }
-
-        callMessageReceivedListeners(decrypted)
-        Database.addMessage(decrypted)
-    }
-  }
-
-  /**
-   * Calls all [[OnMessageReceivedListener]]s with the new message.
-   */
-  private def callMessageReceivedListeners(message: Message): Unit = {
-    MainHandler.post(new Runnable {
-      override def run(): Unit = {
-        messageListeners.foreach(l =>
-          if (l.get != null)
-            l.apply().onMessageReceived(new TreeSet[Message]()(Message.Ordering) + message)
-          else
-            messageListeners -= l)
-      }
-    })
-  }
-
-  /**
-   * Called when a [[ConnectionInfo]] message from a new neighbor is received.
-   */
-  private def onNeighborConnected(info: ConnectionInfo, device: Device.ID): Unit = {
-    val sender = Crypto.calculateAddress(info.key)
-    if (sender == Address.Broadcast || sender == Address.Null) {
-      Log.i(Tag, "Received ConnectionInfo message with invalid sender " + sender + ", ignoring")
-      return
-    }
-
-    if (!Crypto.havePublicKey(sender)) {
-      Crypto.addPublicKey(sender, info.key)
-      Log.i(Tag, "Added public key for new device " + sender.toString)
-    }
-
-    AddressDeviceMap.put(sender, device)
-    Log.i(Tag, "Node " + sender + " connected as " + device)
-
-    connectionListeners.foreach(l => l.get match {
-      case Some(c) => nearbyContactsChanged(c)
-      case None => connectionListeners -= l
-    })
-
-  }
-
-  /**
-   * Registers a listener that is called whenever a new message is sent or received.
-   */
-  def registerMessageListener(listener: OnMessageReceivedListener): Unit = {
-    messageListeners += new WeakReference[OnMessageReceivedListener](listener)
-  }
-
-  /**
-   * Returns the unique bluetooth address of the local device.
-   */
-  private def localDeviceId = new Device.ID(bluetoothAdapter.getAddress)
-
-  def database = Database
-
-}
diff --git a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ConnectThread.scala b/app/src/main/scala/com/nutomic/ensichat/bluetooth/ConnectThread.scala
index 2727e5e..98a21e5 100644
--- a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ConnectThread.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/bluetooth/ConnectThread.scala
@@ -14,7 +14,7 @@ class ConnectThread(device: Device, onConnected: (Device, BluetoothSocket) => Un
   private val Tag = "ConnectThread"
 
   private val Socket: BluetoothSocket =
-      device.bluetoothDevice.createInsecureRfcommSocketToServiceRecord(ChatService.appUuid)
+      device.bluetoothDevice.createInsecureRfcommSocketToServiceRecord(BluetoothInterface.AppUuid)
 
   override def run(): Unit = {
     Log.i(Tag, "Connecting to " + device.toString)
diff --git a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ListenThread.scala b/app/src/main/scala/com/nutomic/ensichat/bluetooth/ListenThread.scala
index d155f48..2d81850 100644
--- a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ListenThread.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/bluetooth/ListenThread.scala
@@ -17,7 +17,7 @@ class ListenThread(name: String, adapter: BluetoothAdapter,
 
   private val ServerSocket: BluetoothServerSocket =
     try {
-      adapter.listenUsingInsecureRfcommWithServiceRecord(name, ChatService.appUuid)
+      adapter.listenUsingInsecureRfcommWithServiceRecord(name, BluetoothInterface.AppUuid)
     } catch {
       case e: IOException =>
         Log.e(Tag, "Failed to create listener", e)
diff --git a/app/src/main/scala/com/nutomic/ensichat/bluetooth/TransferThread.scala b/app/src/main/scala/com/nutomic/ensichat/bluetooth/TransferThread.scala
index 6ad37f3..c507449 100644
--- a/app/src/main/scala/com/nutomic/ensichat/bluetooth/TransferThread.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/bluetooth/TransferThread.scala
@@ -16,8 +16,8 @@ import com.nutomic.ensichat.protocol.messages.{ConnectionInfo, Message, MessageH
  * @param socket An open socket to the given device.
  * @param onReceive Called when a message was received from the other device.
  */
-class TransferThread(device: Device, socket: BluetoothSocket, service: ChatService,
-                     crypto: Crypto, onReceive: (Message, Device.ID) => Unit)
+class TransferThread(device: Device, socket: BluetoothSocket, Handler: BluetoothInterface,
+                     Crypto: Crypto, onReceive: (Message, Device.ID) => Unit)
   extends Thread {
 
   private val Tag: String = "TransferThread"
@@ -43,8 +43,8 @@ class TransferThread(device: Device, socket: BluetoothSocket, service: ChatServi
   override def run(): Unit = {
     Log.i(Tag, "Starting data transfer with " + device.toString)
 
-    send(crypto.sign(new Message(new MessageHeader(ConnectionInfo.Type, ConnectionInfo.HopLimit,
-      Address.Null, Address.Null, 0, 0), new ConnectionInfo(crypto.getLocalPublicKey))))
+    send(Crypto.sign(new Message(new MessageHeader(ConnectionInfo.Type, ConnectionInfo.HopLimit,
+      Address.Null, Address.Null, 0, 0), new ConnectionInfo(Crypto.getLocalPublicKey))))
 
     while (socket.isConnected) {
       try {
@@ -62,8 +62,7 @@ class TransferThread(device: Device, socket: BluetoothSocket, service: ChatServi
           return
       }
     }
-    service.onConnectionChanged(new Device(device.bluetoothDevice, false), null)
-    Log.i(Tag, "Neighbor " + device + " has disconnected")
+    close()
   }
 
   def send(msg: Message): Unit = {
@@ -81,7 +80,7 @@ class TransferThread(device: Device, socket: BluetoothSocket, service: ChatServi
     } catch {
       case e: IOException => Log.e(Tag, "Failed to close socket", e);
     } finally {
-      service.onConnectionChanged(new Device(device.bluetoothDevice, false), null)
+      Handler.onConnectionClosed(new Device(device.bluetoothDevice, false), null)
     }
   }
 
diff --git a/app/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala b/app/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala
index 6b8a5d0..00ca4be 100644
--- a/app/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala
@@ -9,11 +9,10 @@ import android.widget.TextView.OnEditorActionListener
 import android.widget._
 import com.nutomic.ensichat.R
 import com.nutomic.ensichat.activities.EnsiChatActivity
-import com.nutomic.ensichat.bluetooth.ChatService
-import com.nutomic.ensichat.bluetooth.ChatService.OnMessageReceivedListener
-import com.nutomic.ensichat.protocol.Address
+import com.nutomic.ensichat.protocol.{ChatService, Address}
+import com.nutomic.ensichat.protocol.ChatService.OnMessageReceivedListener
 import com.nutomic.ensichat.protocol.messages.{Message, Text}
-import com.nutomic.ensichat.util.MessagesAdapter
+import com.nutomic.ensichat.util.{Database, MessagesAdapter}
 
 import scala.collection.SortedSet
 
@@ -53,7 +52,7 @@ class ChatFragment extends ListFragment with OnClickListener
       // Read local device ID from service,
       adapter = new MessagesAdapter(getActivity, address)
       chatService.registerMessageListener(ChatFragment.this)
-      onMessageReceived(chatService.database.getMessages(address, 15))
+      onMessageReceived(chatService.Database.getMessages(address, 15))
 
       if (listView != null) {
         listView.setAdapter(adapter)
diff --git a/app/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala b/app/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala
index 2dca13f..c646960 100644
--- a/app/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala
@@ -7,7 +7,7 @@ import android.view._
 import android.widget.ListView
 import com.nutomic.ensichat.R
 import com.nutomic.ensichat.activities.{AddContactsActivity, EnsiChatActivity, MainActivity, SettingsActivity}
-import com.nutomic.ensichat.bluetooth.ChatService
+import com.nutomic.ensichat.protocol.ChatService
 import com.nutomic.ensichat.util.DevicesAdapter
 
 /**
@@ -17,7 +17,7 @@ class ContactsFragment extends ListFragment {
 
   private lazy val Adapter = new DevicesAdapter(getActivity)
 
-  private lazy val Database = getActivity.asInstanceOf[EnsiChatActivity].service.database
+  private lazy val Database = getActivity.asInstanceOf[EnsiChatActivity].service.Database
 
   override def onCreate(savedInstanceState: Bundle): Unit = {
     super.onCreate(savedInstanceState)
diff --git a/app/src/main/scala/com/nutomic/ensichat/protocol/ChatService.scala b/app/src/main/scala/com/nutomic/ensichat/protocol/ChatService.scala
new file mode 100644
index 0000000..ee08ea8
--- /dev/null
+++ b/app/src/main/scala/com/nutomic/ensichat/protocol/ChatService.scala
@@ -0,0 +1,192 @@
+package com.nutomic.ensichat.protocol
+
+import android.app.Service
+import android.content.Intent
+import android.os.Handler
+import android.util.Log
+import com.nutomic.ensichat.bluetooth.BluetoothInterface
+import com.nutomic.ensichat.protocol.ChatService.{OnMessageReceivedListener, OnConnectionsChangedListener}
+import com.nutomic.ensichat.protocol.messages.{ConnectionInfo, Message, MessageBody, MessageHeader}
+import com.nutomic.ensichat.util.Database
+
+import scala.collection.SortedSet
+import scala.concurrent.ExecutionContext.Implicits.global
+import scala.concurrent.Future
+import scala.ref.WeakReference
+
+object ChatService {
+
+  abstract class InterfaceHandler {
+
+    def create(): Unit
+
+    def destroy(): Unit
+
+    def send(msg: Message): Unit
+
+  }
+
+  trait OnMessageReceivedListener {
+    def onMessageReceived(messages: SortedSet[Message]): Unit
+  }
+
+  /**
+   * Used with [[ChatService.registerConnectionListener]], called when a Bluetooth device
+   * connects or disconnects
+   */
+  trait OnConnectionsChangedListener {
+    def onConnectionsChanged(devices: Set[Address]): Unit
+  }
+
+}
+
+/**
+ * High-level handling of all message transfers and callbacks.
+ */
+class ChatService extends Service {
+
+  private val Tag = "ChatService"
+
+  lazy val Database = new Database(this)
+
+  val MainHandler = new Handler()
+
+  private lazy val Binder = new ChatServiceBinder(this)
+
+  private lazy val Crypto = new Crypto(this)
+
+  private lazy val BluetoothInterface = new BluetoothInterface(this, Crypto)
+
+  /**
+   * For this (and [[messageListeners]], functions would be useful instead of instances,
+   * but on a Nexus S (Android 4.1.2), these functions are garbage collected even when
+   * referenced.
+   */
+  private var connectionListeners = Set[WeakReference[OnConnectionsChangedListener]]()
+
+  private var messageListeners = Set[WeakReference[OnMessageReceivedListener]]()
+
+  /**
+   * Generates keys and starts Bluetooth interface.
+   */
+  override def onCreate(): Unit = {
+    super.onCreate()
+
+    Future {
+      Crypto.generateLocalKeys()
+      Log.i(Tag, "Service started, address is " + Crypto.getLocalAddress)
+
+      BluetoothInterface.create()
+    }
+  }
+
+  override def onDestroy(): Unit = {
+    BluetoothInterface.destroy()
+  }
+
+  override def onStartCommand(intent: Intent, flags: Int, startId: Int) = Service.START_STICKY
+
+  override def onBind(intent: Intent) =  Binder
+
+  /**
+   * Registers a listener that is called whenever a new message is sent or received.
+   */
+  def registerMessageListener(listener: OnMessageReceivedListener): Unit = {
+    messageListeners += new WeakReference[OnMessageReceivedListener](listener)
+  }
+
+  /**
+   * Registers a listener that is called whenever a new device is connected.
+   */
+  def registerConnectionListener(listener: OnConnectionsChangedListener): Unit = {
+    connectionListeners += new WeakReference[OnConnectionsChangedListener](listener)
+    listener.onConnectionsChanged(BluetoothInterface.getConnections)
+  }
+
+  /**
+   * Sends a new message to the given target address.
+   */
+  def sendTo(target: Address, body: MessageBody): Unit = {
+    if (!BluetoothInterface.getConnections.contains(target))
+      return
+
+    val header = new MessageHeader(body.Type, MessageHeader.DefaultHopLimit,
+      Crypto.getLocalAddress, target, 0, 0)
+
+    val msg = new Message(header, body)
+    val encrypted = Crypto.encrypt(Crypto.sign(msg))
+    BluetoothInterface.send(encrypted)
+    onNewMessage(msg)
+  }
+
+  /**
+   * Decrypts and verifies incoming messages, forwards valid ones to [[onNewMessage()]].
+   */
+  def onMessageReceived(msg: Message): Unit = {
+    val decrypted = Crypto.decrypt(msg)
+    if (!Crypto.verify(decrypted)) {
+      Log.i(Tag, "Ignoring message with invalid signature from " + msg.Header.Origin)
+      return
+    }
+    onNewMessage(decrypted)
+  }
+
+  /**
+   * Calls all [[OnMessageReceivedListener]]s with the new message.
+   *
+   * This function is called both for locally and remotely sent messages.
+   */
+  private def onNewMessage(msg: Message): Unit = {
+    Database.addMessage(msg)
+    MainHandler.post(new Runnable {
+      override def run(): Unit =
+        messageListeners
+          .filter(_.get.nonEmpty)
+          .foreach(_.apply().onMessageReceived(SortedSet(msg)(Message.Ordering)))
+    })
+  }
+
+  /**
+   * Opens connection to a direct neighbor.
+   *
+   * This adds the other node's public key if we don't have it. If we do, it validates the signature
+   * with the stored key.
+   *
+   * The caller must invoke [[callConnectionListeners()]]
+   *
+   * @param infoMsg The message containing [[ConnectionInfo]] to open the connection.
+   * @return True if the connection is valid
+   */
+  def onConnectionOpened(infoMsg: Message): Option[Address] = {
+    val info = infoMsg.Body.asInstanceOf[ConnectionInfo]
+    val sender = Crypto.calculateAddress(info.key)
+    if (sender == Address.Broadcast || sender == Address.Null) {
+      Log.i(Tag, "Ignoring ConnectionInfo message with invalid sender " + sender)
+      None
+    }
+
+    if (Crypto.havePublicKey(sender) && !Crypto.verify(infoMsg, Crypto.getPublicKey(sender))) {
+      Log.i(Tag, "Ignoring ConnectionInfo message with invalid signature")
+      None
+    }
+
+    if (!Crypto.havePublicKey(sender)) {
+      Crypto.addPublicKey(sender, info.key)
+      Log.i(Tag, "Added public key for new device " + sender.toString)
+    }
+
+    Log.i(Tag, "Node " + sender + " connected")
+    Some(sender)
+  }
+
+  /**
+   * Calls all [[connectionListeners]] with the currently active connections.
+   *
+   * Should be called whenever a neighbor connects or disconnects.
+   */
+  def callConnectionListeners(): Unit =
+    connectionListeners
+      .filter(_ != None)
+      .foreach(_.apply().onConnectionsChanged(BluetoothInterface.getConnections))
+
+}
\ No newline at end of file
diff --git a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ChatServiceBinder.scala b/app/src/main/scala/com/nutomic/ensichat/protocol/ChatServiceBinder.scala
similarity index 75%
rename from app/src/main/scala/com/nutomic/ensichat/bluetooth/ChatServiceBinder.scala
rename to app/src/main/scala/com/nutomic/ensichat/protocol/ChatServiceBinder.scala
index 77dccd5..27ca6be 100644
--- a/app/src/main/scala/com/nutomic/ensichat/bluetooth/ChatServiceBinder.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/protocol/ChatServiceBinder.scala
@@ -1,4 +1,4 @@
-package com.nutomic.ensichat.bluetooth
+package com.nutomic.ensichat.protocol
 
 import android.os.Binder