Allow sending bitcoins in chat.

2015-09-12 20:23:28 +02:00
194 changed files with 3319 additions and 5448 deletions
--- a/.gitignore
+++ b/.gitignore
@ -4,5 +4,4 @@
 /build
 *.iml
 *.iws
-*.ipr
-*.apk
+*.ipr
--- a/.gitmodules
+++ b/.gitmodules
@ -1,3 +0,0 @@
-[submodule "buildSrc"]
-	path = buildSrc
-	url = https://github.com/xelnaga/gradle-android-scala-plugin.git
--- a/.travis.yml
+++ b/.travis.yml
@ -1,32 +0,0 @@
-language: android
-jdk: oraclejdk8
-
-# Install Android SDK
-android:
-  components:
-    - tools
-    - platform-tools
-    - build-tools-24.0.2
-    - android-24
-    - extra-android-m2repository
-
-# Cache gradle dependencies
-# https://docs.travis-ci.com/user/languages/android/#Caching
-before_cache:
-  - rm -f $HOME/.gradle/caches/modules-2/modules-2.lock
-cache:
-  directories:
-    - $HOME/.gradle/caches/
-    - $HOME/.gradle/wrapper/
-
-env:
-  - GRADLE_OPTS=-Xmx2048m
-
-script:
-  # Lint fails because travis doesn't have platform-tools 24
-  # https://github.com/travis-ci/travis-ci/issues/6699
-  #- ./gradlew lint
-  - ./gradlew core:test
-  - ./gradlew server:release
-  - ./gradlew integration:assemble
-  - ./gradlew android:assembleRelRelease || ./gradlew android:assembleRelRelease
--- a/1046
+++ b/1046
--- a/PROTOCOL.md
+++ b/PROTOCOL.md
@ -26,9 +26,6 @@ Nodes MUST NOT have a public key with the broadcast address or null
 address as hash. Additionally, nodes MUST NOT connect to a node with
 either address.

-All integer fields are in network byte order, and unsigned (unless 
-specified otherwise).
-

 Crypto
 ------
@ -43,15 +40,22 @@ private key, and the result written to the 'Encryption Data' part.

 Routing
 -------
-The routing protocol is based on 
-[AODVv2](https://datatracker.ietf.org/doc/draft-ietf-manet-aodvv2/),
-with various features left out.
+A simple flood routing protocol is currently used. Every node forwards
+all messages, unless a message with the same Origin and Sequence Number
+has already been received.

-TODO: Add Documentation for routing protocol.
+Nodes MUST store pairs of (Origin, Sequence Number) for all received
+messages. After receiving a new message, entries with the same Origin
+and Sequence Number between _received_ + 1 and _received_ + 32767 MUST
+be removed (with a wrap around at the maximum value). The entries MUST
+NOT be cleared while the program is running. They MAY be cleared when
+the program is exited.

 There is currently no support for offline messages. If sender and
 receiver are not in the same mesh, the message will not arrive.

+Nodes are free implement different routing algorithms.
+

 Messages
 --------
@ -80,12 +84,14 @@ AES key is wrapped with the recipient's public RSA key.
 ### Header

 Every message starts with one 74 byte header indicating the message
-version, type and ID, followed by the length of the message.
+version, type and ID, followed by the length of the message. The
+header is in network byte order, i.e. big endian. The header may have
+6 bytes of additional data.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |    Version    | Protocol-Type |    Tokens     |   Hop Count   |
+    |    Version    | Protocol-Type |   Hop Limit   |   Hop Count   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                            Length                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
@ -111,8 +117,8 @@ where such a packet came from MAY be closed.
 Protocol-Type is one of those specified in section Protocol Messages,
 or 255 for Content Messages.

-Tokens is the number of times this message should be copied to
-different relays.
+Hop Limit SHOULD be set to `MAX_HOP_COUNT` on message creation, and
+MUST NOT be changed by a forwarding node.

 Hop Count specifies the number of nodes a message may pass. When
 creating a package, it is initialized to 0. Whenever a node forwards
@ -214,100 +220,6 @@ After this message has been received, communication with normal messages
 may start.


-### Route Request (Protocol-Type = 2)
-
-Sent to request a route to a specific Target Address.
-
-     0                   1                   2                   3
-     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                                                               |
-    |                      Address (32 bytes)                       |
-    |                                                               |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |           OrigSeqNum          |         OriginMetric          |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                          TargMetric                           |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-Equivalent to the Sequence Number in the message header.
-
-Set OrigMetric = RouterClient.Cost for the Router Client entry
-which includes OrigAddr.
-
-If an Invalid route exists in the Local Route Set matching
-TargAddr using longest prefix matching and has a valid
-sequence number, set TargSeqNum = LocalRoute.SeqNum.
-Otherwise, set TargSeqNum = -1. This field is signed.
-
-### Route Reply (Protocol-Type = 3)
-
-Sent as a reply when a Route Request arrives, to inform other nodes
-about a route.
-
-     0                   1                   2                   3
-     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |           TargSeqNum          |          TargMetric           |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-Set TargMetric = RouterClient.Cost for the Router Client entry
-which includes TargAddr.
-
-### Route Error (Protocol-Type = 4)
-
-Notifies other nodes of routes that are no longer available. The target
-address MUST be set to the broadcast address.
-
-     0                   1                   2                   3
-     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                                                               |
-    |                   Packet Source (32 bytes)                    |
-    |                                                               |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                                                               |
-    |                      Address (32 bytes)                       |
-    |                                                               |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                           SeqNum                              |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-Packet Source is the source address of the message triggering this
-Route Error. If the route error is not triggered by a message,
-this MUST be set to the null address.
-
-Address is the address that is no longer reachable.
-
-SeqNum is the sequence number of the route that is no longer available
-(if known). Otherwise, set TargSeqNum = -1. This field is signed.
-
-### PublicKeyRequest (Protocol-Type = 5)
-
-     0                   1                   2                   3
-     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                            Address                            |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    
-Contains an address for which the sender wants the corresponding public
-key.
-
-### PublicKeyReply (Protocol-Type = 6)
-
-     0                   1                   2                   3
-     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                          Key Length                           |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    /                                                               /
-    \                   Key (variable length)                       \
-    /                                                               /
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    
-Contains a node's public key in binary form. Sent in reply to a
-PublicKeyRequest.
-
 Content Messages
 ----------------

@ -354,13 +266,28 @@ Text the string to be transferred, encoded as UTF-8.
 Contains the sender's name and status, which should be used for
 display to users.

-### MessageReceived (Content-Type = 8)
+### InitiatePayment (Type = 5)
+
+Requests PaymentRequest message.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                           Message ID                          |
+    |                           Reserved                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    
-Confirms that a previous content message has been received by the
-target node. Message ID is the ID of that message.
+
+### PaymentInformation (Type = 6)
+
+Contains Bitcoin payment info.
+
+     0                   1                   2                   3
+     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |                    Payment Request Length                     |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    /                                                               /
+    \              Payment Request (variable length)                \
+    /                                                               /
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+Payment Request is a protobuf-formatted Bitcoin payment message.
--- a/README.md
+++ b/README.md
@ -1,24 +1,11 @@
-PROJECT DISCONTINUED
-====================
-
-Unfortunately, I won't be able to continue development on Ensichat, due to lack of time. I suggest
-you give [Briar](https://briarproject.org/) a try instead.
-
-If you wish to take over maintenance of the project, please contact me.
-
 Ensichat
 ========

-[![Build Status](https://travis-ci.org/Nutomic/ensichat.svg?branch=master)](https://travis-ci.org/Nutomic/ensichat)
-[![License: MPLv2](https://img.shields.io/badge/License-MPLv2-blue.svg)](https://opensource.org/licenses/MPL-2.0)
+[![BitCoin donate button](https://img.shields.io/badge/bitcoin-donate-yellow.svg)](https://blockchain.info/address/1DmU6QVGSKXGXJU1bqmmStPDNsNnYoMJB4)

-Instant messenger for Android that is fully decentralized, and uses strong end-to-end
-encryption. Messages are sent directly between devices via Bluetooth or Internet, without any
-central server. Relay nodes are used to ensure message delivery, even if the target node is 
-offline.
-
-For details on how Ensichat works, you can check out my [bachelor thesis](docs/bachelor-thesis.pdf), and
-read the [protocol definition](PROTOCOL.md).
+Instant messanger for Android that is fully decentralized. Messages are sent directly between
+devices via Bluetooth, without any central server. A simple flood-based routing is used for
+message propagation.

 <img src="graphics/screenshot_phone_1.png" alt="screenshot 1" width="200" />
 <img src="graphics/screenshot_phone_2.png" alt="screenshot 2" width="200" />
@ -26,31 +13,14 @@ read the [protocol definition](PROTOCOL.md).

 [![Get it on Google Play](https://developer.android.com/images/brand/en_generic_rgb_wo_60.png)](https://play.google.com/store/apps/details?id=com.nutomic.ensichat) [![Get it on F-Droid](https://f-droid.org/wiki/images/0/06/F-Droid-button_get-it-on.png)](https://f-droid.org/repository/browse/?fdid=com.nutomic.ensichat)

-To set up a server, please follow the [instructions on the wiki](https://github.com/Nutomic/ensichat/wiki/Running-your-own-server).
-
 Building
 --------

-To setup a development environment, just install [Android Studio](https://developer.android.com/sdk/)
-and import the project.
+To create a debug apk, run `./gradlew assembleDevDebug`. This requires at least Android Lollipop on your development device. If you don't have Lollipop, you can alternatively use `./gradlew assembleRelDebug`. However, this results in considerably slower incremental builds

-Alternatively, you can use the command line. To create a debug apk, run `./gradlew assembleDevDebug`.
-This requires at least Android Lollipop on your development device. If you don't have 5.0 or higher,
-you have to use `./gradlew assembleRelDebug`. However, this results in considerably slower
-incremental builds. To create a release apk, run `./gradlew assembleRelRelease`.
-
-Testing
-------
-
-You can run the unit tests with `./gradlew test`. After connecting an Android device, you can run
-the Android tests with `./gradlew connectedDevDebugAndroidTest` (or
-`./gradlew connectedRelDebugAndroidTest` if your Android version is  lower than 5.0).
-
-To run integration tests for the core module, use `./gradlew integration:run`. If this fails (or
-is very slow), try changing the value of Crypto#PublicKeySize to 512 (in the core module).
+To create a release apk, run `./gradlew assembleRelRelease`.

 License
 -------
-The project is licensed under the [MPLv2](LICENSE).

-The launcher icon is based on the [Bubbles Icon](https://www.iconfinder.com/icons/285667/bubbles_icon) created by [Paomedia](https://www.iconfinder.com/paomedia) which is available under [CC BY 3.0](http://creativecommons.org/licenses/by/3.0/).
+All code is licensed under the [GPL](LICENSE), v3 or later.
--- a/android/src/main/res/drawable-hdpi/ic_add_white_24dp.png
+++ b/android/src/main/res/drawable-hdpi/ic_add_white_24dp.png
--- a/android/src/main/res/drawable-hdpi/ic_launcher.png
+++ b/android/src/main/res/drawable-hdpi/ic_launcher.png
--- a/android/src/main/res/drawable-hdpi/ic_person_add_white_24dp.png
+++ b/android/src/main/res/drawable-hdpi/ic_person_add_white_24dp.png
--- a/android/src/main/res/drawable-hdpi/ic_qrcode_white_24dp.png
+++ b/android/src/main/res/drawable-hdpi/ic_qrcode_white_24dp.png
--- a/android/src/main/res/drawable-mdpi/ic_add_white_24dp.png
+++ b/android/src/main/res/drawable-mdpi/ic_add_white_24dp.png
--- a/android/src/main/res/drawable-mdpi/ic_launcher.png
+++ b/android/src/main/res/drawable-mdpi/ic_launcher.png
--- a/android/src/main/res/drawable-mdpi/ic_person_add_white_24dp.png
+++ b/android/src/main/res/drawable-mdpi/ic_person_add_white_24dp.png
--- a/android/src/main/res/drawable-mdpi/ic_qrcode_white_24dp.png
+++ b/android/src/main/res/drawable-mdpi/ic_qrcode_white_24dp.png
--- a/android/src/main/res/drawable-xhdpi/ic_add_white_24dp.png
+++ b/android/src/main/res/drawable-xhdpi/ic_add_white_24dp.png
--- a/android/src/main/res/drawable-xhdpi/ic_launcher.png
+++ b/android/src/main/res/drawable-xhdpi/ic_launcher.png
--- a/android/src/main/res/drawable-xhdpi/ic_person_add_white_24dp.png
+++ b/android/src/main/res/drawable-xhdpi/ic_person_add_white_24dp.png
--- a/android/src/main/res/drawable-xhdpi/ic_qrcode_white_24dp.png
+++ b/android/src/main/res/drawable-xhdpi/ic_qrcode_white_24dp.png
--- a/android/src/main/res/drawable-xxhdpi/ic_add_white_24dp.png
+++ b/android/src/main/res/drawable-xxhdpi/ic_add_white_24dp.png
--- a/android/src/main/res/drawable-xxhdpi/ic_launcher.png
+++ b/android/src/main/res/drawable-xxhdpi/ic_launcher.png
--- a/android/src/main/res/drawable-xxhdpi/ic_person_add_white_24dp.png
+++ b/android/src/main/res/drawable-xxhdpi/ic_person_add_white_24dp.png
--- a/android/src/main/res/drawable-xxhdpi/ic_qrcode_white_24dp.png
+++ b/android/src/main/res/drawable-xxhdpi/ic_qrcode_white_24dp.png
--- a/android/src/main/res/drawable-xxxhdpi/ic_add_white_24dp.png
+++ b/android/src/main/res/drawable-xxxhdpi/ic_add_white_24dp.png
--- a/android/src/main/res/drawable-xxxhdpi/ic_launcher.png
+++ b/android/src/main/res/drawable-xxxhdpi/ic_launcher.png
--- a/android/src/main/res/drawable-xxxhdpi/ic_person_add_white_24dp.png
+++ b/android/src/main/res/drawable-xxxhdpi/ic_person_add_white_24dp.png
--- a/android/src/main/res/drawable-xxxhdpi/ic_qrcode_white_24dp.png
+++ b/android/src/main/res/drawable-xxxhdpi/ic_qrcode_white_24dp.png
--- a/android/src/main/res/layout/fragment_contacts.xml
+++ b/android/src/main/res/layout/fragment_contacts.xml
@ -1,87 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:orientation="vertical"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent">
-
-    <android.support.design.widget.AppBarLayout
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content">
-
-        <android.support.v7.widget.Toolbar
-            android:id="@+id/toolbar"
-            android:layout_height="?attr/actionBarSize"
-            android:layout_width="match_parent"
-            android:background="?attr/colorPrimary"
-            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
-            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
-            android:contentInsetLeft="0dp"
-            android:contentInsetStart="0dp"
-            app:contentInsetLeft="0dp"
-            app:contentInsetStart="0dp">
-
-            <LinearLayout
-                android:layout_width="match_parent"
-                android:layout_height="match_parent"
-                android:id="@+id/title_holder"
-                android:orientation="vertical"
-                android:clickable="true"
-                android:background="?attr/selectableItemBackgroundBorderless"
-                android:gravity="center_vertical"
-                android:paddingLeft="10dp"
-                android:paddingStart="10dp">
-
-                <TextView
-                    android:layout_width="wrap_content"
-                    android:layout_height="wrap_content"
-                    android:id="@+id/title"
-                    android:textSize="20sp"
-                    android:textStyle="bold" />
-
-                <TextView
-                    android:layout_width="wrap_content"
-                    android:layout_height="wrap_content"
-                    android:id="@+id/subtitle"
-                    android:textSize="16sp"
-                    android:singleLine="true"
-                    android:ellipsize="end" />
-
-            </LinearLayout>
-
-        </android.support.v7.widget.Toolbar>
-
-    </android.support.design.widget.AppBarLayout>
-
-    <RelativeLayout
-        android:layout_width="match_parent"
-        android:layout_height="0dp"
-        android:layout_weight="1">
-
-        <ListView
-            android:id="@android:id/list"
-            android:layout_width="fill_parent"
-            android:layout_height="fill_parent" />
-
-        <TextView
-            android:id="@android:id/empty"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:text="@string/no_contacts_found"
-            android:layout_centerHorizontal="true"
-            android:layout_centerVertical="true" />
-
-        <android.support.design.widget.FloatingActionButton
-            android:id="@+id/fab"
-            android:layout_margin="20dp"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:src="@drawable/ic_add_white_24dp"
-            android:layout_alignParentBottom="true"
-            android:layout_alignParentRight="true"
-            android:layout_alignParentEnd="true" />
-
-    </RelativeLayout>
-
-</LinearLayout>
--- a/android/src/main/res/layout/fragment_identicon.xml
+++ b/android/src/main/res/layout/fragment_identicon.xml
@ -1,34 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent">
-
-    <LinearLayout
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:orientation="vertical"
-        android:gravity="center"
-        android:padding="25dp">
-
-        <ImageView
-            android:id="@+id/identicon"
-            android:layout_width="150dp"
-            android:layout_height="150dp"
-            android:scaleType="fitCenter" />
-
-        <TextView
-            android:id="@+id/address"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="25dp"
-            android:layout_marginBottom="25dp" />
-
-        <ImageView
-            android:id="@+id/qr_code"
-            android:layout_width="150dp"
-            android:layout_height="150dp"
-            android:scaleType="fitCenter" />
-
-    </LinearLayout>
-
-</ScrollView>
--- a/android/src/main/res/menu/connections.xml
+++ b/android/src/main/res/menu/connections.xml
@ -1,17 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<menu xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto">
-
-    <item
-        android:id="@+id/add_contact"
-        android:title="@string/add_contact"
-        android:icon="@drawable/ic_person_add_white_24dp"
-        app:showAsAction="ifRoom" />
-
-    <item
-        android:id="@+id/scan_qr"
-        android:title="@string/scan_qr_code"
-        android:icon="@drawable/ic_qrcode_white_24dp"
-        app:showAsAction="ifRoom" />
-
-</menu>
--- a/android/src/main/scala/com/nutomic/ensichat/App.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/App.scala
@ -1,13 +0,0 @@
-package com.nutomic.ensichat
-
-import android.support.multidex.MultiDexApplication
-import com.nutomic.ensichat.util.PRNGFixes
-
-class App extends MultiDexApplication {
-
-  override def onCreate(): Unit = {
-    super.onCreate()
-    PRNGFixes.apply()
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/activities/ConnectionsActivity.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/activities/ConnectionsActivity.scala
@ -1,156 +0,0 @@
-package com.nutomic.ensichat.activities
-
-import android.app.Activity
-import android.app.AlertDialog.Builder
-import android.content.DialogInterface.OnClickListener
-import android.content._
-import android.os.Bundle
-import android.support.v4.app.NavUtils
-import android.support.v4.content.LocalBroadcastManager
-import android.view._
-import android.widget.AdapterView.OnItemClickListener
-import android.widget._
-import com.google.zxing.integration.android.IntentIntegrator
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.core.routing.Address
-import com.nutomic.ensichat.service.CallbackHandler
-import com.nutomic.ensichat.views.UsersAdapter
-
-/**
- * Lists all nearby, connected devices and allows adding them to be added as contacts.
- */
-class ConnectionsActivity extends EnsichatActivity with OnItemClickListener {
-
-  private lazy val adapter = new UsersAdapter(this)
-
-  /**
-   * Initializes layout, registers connection and message listeners.
-   */
-  override def onCreate(savedInstanceState: Bundle): Unit = {
-    super.onCreate(savedInstanceState)
-    getSupportActionBar.setDisplayHomeAsUpEnabled(true)
-
-    setContentView(R.layout.activity_connections)
-    val list = findViewById(android.R.id.list).asInstanceOf[ListView]
-    list.setAdapter(adapter)
-    list.setOnItemClickListener(this)
-    list.setEmptyView(findViewById(android.R.id.empty))
-
-    val filter = new IntentFilter()
-    filter.addAction(CallbackHandler.ActionConnectionsChanged)
-    filter.addAction(CallbackHandler.ActionContactsUpdated)
-    LocalBroadcastManager.getInstance(this)
-      .registerReceiver(onContactsUpdatedReceiver, filter)
-  }
-
-  override def onResume(): Unit = {
-    super.onResume()
-    runOnServiceConnected(() => {
-      updateConnections()
-    })
-  }
-
-  override def onDestroy(): Unit = {
-    super.onDestroy()
-    LocalBroadcastManager.getInstance(this).unregisterReceiver(onContactsUpdatedReceiver)
-  }
-
-  override def onCreateOptionsMenu(menu: Menu): Boolean = {
-    getMenuInflater.inflate(R.menu.connections, menu)
-    true
-  }
-
-  override def onOptionsItemSelected(item: MenuItem): Boolean = item.getItemId match {
-    case R.id.add_contact =>
-        val et = new EditText(this)
-        new Builder(this)
-          .setTitle(R.string.enter_id)
-          .setView(et)
-          .setPositiveButton(android.R.string.ok, new OnClickListener {
-            override def onClick(dialog: DialogInterface, which: Int): Unit = {
-              addContact(et.getText.toString)
-            }
-          })
-          .setNegativeButton(android.R.string.cancel, null)
-          .show()
-      true
-    case R.id.scan_qr =>
-      new IntentIntegrator(this).initiateScan
-      true
-    case android.R.id.home =>
-      NavUtils.navigateUpFromSameTask(this)
-      true
-    case _ =>
-      super.onOptionsItemSelected(item)
-  }
-
-  /**
-   * Initiates adding the device as contact if it hasn't been added yet.
-   */
-  override def onItemClick(parent: AdapterView[_], view: View, position: Int, id: Long): Unit =
-    addContact(adapter.getItem(position).address.toString)
-
-  /**
-   * Receives value of scanned QR code and sets it as device ID.
-   */
-  override def onActivityResult(requestCode: Int, resultCode: Int, intent: Intent) {
-    val scanResult = IntentIntegrator.parseActivityResult(requestCode, resultCode, intent)
-    if (scanResult != null && resultCode == Activity.RESULT_OK) {
-      addContact(scanResult.getContents)
-    }
-  }
-
-  /**
-   * Parses the address, and shows a dialog to add the user as a contact.
-   *
-   * Displays a warning toast if the address is invalid or if the user is already a contact.
-   */
-  private def addContact(address: String): Unit = {
-    val parsedAddress =
-      try {
-        new Address(address)
-      } catch {
-        case e: IllegalArgumentException =>
-          Toast.makeText(this, R.string.invalid_address, Toast.LENGTH_LONG).show()
-          return
-      }
-
-    val user = service.get.getUser(parsedAddress)
-
-    if (database.get.getContacts.map(_.address).contains(user.address)) {
-      val text = getString(R.string.contact_already_added, user.name)
-      Toast.makeText(this, text, Toast.LENGTH_SHORT).show()
-      return
-    }
-
-    new Builder(this)
-      .setMessage(getString(R.string.dialog_add_contact, user.name))
-      .setPositiveButton(android.R.string.yes, new OnClickListener {
-        override def onClick(dialog: DialogInterface, which: Int): Unit = {
-          service.get.addContact(user)
-          Toast.makeText(ConnectionsActivity.this, R.string.toast_contact_added, Toast.LENGTH_SHORT)
-            .show()
-        }
-      })
-      .setNegativeButton(android.R.string.no, null)
-      .show()
-  }
-
-  /**
-   * Fetches connections and displays them (excluding contacts).
-   */
-  private val onContactsUpdatedReceiver = new BroadcastReceiver() {
-    override def onReceive(context: Context, intent: Intent): Unit = {
-      runOnUiThread(new Runnable {
-        override def run(): Unit = updateConnections()
-      })
-    }
-  }
-
-  private def updateConnections(): Unit = {
-    adapter.clear()
-    service.get.connections().map(a => service.get.getUser(a))
-      .foreach(adapter.add)
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala
@ -1,140 +0,0 @@
-package com.nutomic.ensichat.fragments
-
-import android.app.ListFragment
-import android.content.{BroadcastReceiver, Context, Intent, IntentFilter}
-import android.os.Bundle
-import android.support.v4.content.LocalBroadcastManager
-import android.support.v7.widget.Toolbar
-import android.view.View.OnClickListener
-import android.view.inputmethod.EditorInfo
-import android.view.{KeyEvent, LayoutInflater, View, ViewGroup}
-import android.widget.TextView.OnEditorActionListener
-import android.widget._
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.activities.EnsichatActivity
-import com.nutomic.ensichat.core.messages.body.Text
-import com.nutomic.ensichat.core.messages.Message
-import com.nutomic.ensichat.core.routing.Address
-import com.nutomic.ensichat.core.ConnectionHandler
-import com.nutomic.ensichat.service.CallbackHandler
-import com.nutomic.ensichat.views.{DatesAdapter, MessagesAdapter}
-
-/**
- * Represents a single chat with another specific device.
- */
-class ChatFragment extends ListFragment with OnClickListener {
-
-  /**
-   * Fragments need to have a default constructor, so this is optional.
-   */
-  def this(address: Address) {
-    this
-    this.address = address
-  }
-
-  private lazy val activity = getActivity.asInstanceOf[EnsichatActivity]
-
-  private var address: Address = _
-
-  private var chatService: ConnectionHandler = _
-
-  private var sendButton: Button = _
-
-  private var messageText: EditText = _
-
-  private var listView: ListView = _
-
-  private var adapter: DatesAdapter = _
-
-  override def onActivityCreated(savedInstanceState: Bundle): Unit = {
-    super.onActivityCreated(savedInstanceState)
-
-    activity.runOnServiceConnected(() => {
-      chatService = activity.service.get
-
-      activity.database.get.getContact(address).foreach(c => getActivity.setTitle(c.name))
-
-      adapter = new DatesAdapter(getActivity,
-        new MessagesAdapter(getActivity, activity.database.get.getMessages(address), address))
-
-      if (listView != null) {
-        listView.setAdapter(adapter)
-      }
-    })
-  }
-
-  override def onCreateView(inflater: LayoutInflater, container: ViewGroup,
-                            savedInstanceState: Bundle): View = {
-    val view =  inflater.inflate(R.layout.fragment_chat, container, false)
-    val toolbar = view.findViewById(R.id.toolbar).asInstanceOf[Toolbar]
-    activity.setSupportActionBar(toolbar)
-    activity.getSupportActionBar.setDisplayHomeAsUpEnabled(true)
-    sendButton = view.findViewById(R.id.send).asInstanceOf[Button]
-    sendButton.setOnClickListener(this)
-    messageText = view.findViewById(R.id.message).asInstanceOf[EditText]
-    messageText.setOnEditorActionListener(new OnEditorActionListener {
-      override def onEditorAction(view: TextView, actionId: Int, event: KeyEvent): Boolean = {
-        if (actionId == EditorInfo.IME_ACTION_DONE) {
-          onClick(sendButton)
-          true
-        } else
-          false
-      }
-    })
-    listView = view.findViewById(android.R.id.list).asInstanceOf[ListView]
-    listView.setAdapter(adapter)
-    view
-  }
-
-  override def onCreate(savedInstanceState: Bundle): Unit = {
-    super.onCreate(savedInstanceState)
-
-    if (savedInstanceState != null)
-      address = new Address(savedInstanceState.getByteArray("address"))
-
-    LocalBroadcastManager.getInstance(getActivity)
-      .registerReceiver(onMessageReceivedReceiver, new IntentFilter(CallbackHandler.ActionMessageReceived))
-  }
-
-  override def onSaveInstanceState(outState: Bundle): Unit = {
-    super.onSaveInstanceState(outState)
-    outState.putByteArray("address", address.bytes)
-  }
-
-  override def onDestroy(): Unit = {
-    super.onDestroy()
-    LocalBroadcastManager.getInstance(getActivity).unregisterReceiver(onMessageReceivedReceiver)
-  }
-
-  /**
-   * Send message if send button was clicked.
-   */
-  override def onClick(view: View): Unit = view.getId match {
-    case R.id.send =>
-      val text = messageText.getText.toString.trim
-      if (!text.isEmpty) {
-        val message = new Text(text.toString)
-        chatService.sendTo(address, message)
-        messageText.getText.clear()
-      }
-  }
-
-  /**
-   * Displays new messages in UI.
-   */
-  private val onMessageReceivedReceiver = new BroadcastReceiver {
-    override def onReceive(context: Context, intent: Intent): Unit = {
-      val msg = intent.getSerializableExtra(CallbackHandler.ExtraMessage).asInstanceOf[Message]
-      if (!Set(msg.header.origin, msg.header.target).contains(address))
-        return
-
-      msg.body match {
-        case _: Text =>
-          val messages = activity.database.get.getMessages(address)
-          adapter.replaceItems(messages)
-        case _ =>
-      }
-    }
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala
@ -1,160 +0,0 @@
-package com.nutomic.ensichat.fragments
-
-import java.io.File
-
-import android.app.ListFragment
-import android.bluetooth.BluetoothAdapter
-import android.content.{BroadcastReceiver, Context, Intent, IntentFilter}
-import android.net.Uri
-import android.os.Bundle
-import android.preference.PreferenceManager
-import android.support.design.widget.FloatingActionButton
-import android.support.v4.content.{ContextCompat, LocalBroadcastManager}
-import android.support.v7.widget.Toolbar
-import android.view.View.OnClickListener
-import android.view._
-import android.widget.{ListView, TextView}
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.activities.{ConnectionsActivity, EnsichatActivity, MainActivity, SettingsActivity}
-import com.nutomic.ensichat.core.interfaces.SettingsInterface
-import com.nutomic.ensichat.service.{CallbackHandler, ChatService}
-import com.nutomic.ensichat.views.UsersAdapter
-
-import scala.collection.JavaConversions._
-
-/**
- * Lists all nearby, connected devices.
- */
-class ContactsFragment extends ListFragment with OnClickListener {
-
-  private lazy val adapter = new UsersAdapter(getActivity)
-
-  private lazy val database = activity.database.get
-
-  private lazy val lbm = LocalBroadcastManager.getInstance(getActivity)
-
-  private lazy val activity = getActivity.asInstanceOf[EnsichatActivity]
-
-  private var title: TextView = _
-  private var subtitle: TextView = _
-
-  override def onCreate(savedInstanceState: Bundle): Unit = {
-    super.onCreate(savedInstanceState)
-
-    setListAdapter(adapter)
-    setHasOptionsMenu(true)
-    lbm.registerReceiver(onContactsUpdatedListener, new IntentFilter(CallbackHandler.ActionContactsUpdated))
-    lbm.registerReceiver(onConnectionsChangedListener, new IntentFilter(CallbackHandler.ActionConnectionsChanged))
-  }
-
-  override def onResume(): Unit = {
-    super.onResume()
-    activity.runOnServiceConnected(() => {
-      adapter.clear()
-      adapter.addAll(database.getContacts)
-      updateConnections()
-    })
-  }
-
-  override def onDestroy(): Unit = {
-    super.onDestroy()
-    lbm.unregisterReceiver(onContactsUpdatedListener)
-    lbm.unregisterReceiver(onConnectionsChangedListener)
-  }
-
-  override def onCreateView(inflater: LayoutInflater, container: ViewGroup,
-                            savedInstanceState: Bundle): View = {
-    val v = inflater.inflate(R.layout.fragment_contacts, container, false)
-    val toolbar = v.findViewById(R.id.toolbar).asInstanceOf[Toolbar]
-    v.findViewById(R.id.title_holder).setOnClickListener(this)
-    activity.setSupportActionBar(toolbar)
-    toolbar.setNavigationIcon(R.drawable.ic_launcher)
-    title = v.findViewById(R.id.title).asInstanceOf[TextView]
-    subtitle = v.findViewById(R.id.subtitle).asInstanceOf[TextView]
-    val fab = v.findViewById(R.id.fab).asInstanceOf[FloatingActionButton]
-    fab.setOnClickListener(this)
-    updateConnections()
-    v
-  }
-
-  override def onCreateOptionsMenu(menu: Menu, inflater: MenuInflater): Unit = {
-    super.onCreateOptionsMenu(menu, inflater)
-    inflater.inflate(R.menu.main, menu)
-  }
-
-  override def onClick(v: View): Unit =
-    startActivity(new Intent(getActivity, classOf[ConnectionsActivity]))
-
-  override def onOptionsItemSelected(item: MenuItem): Boolean = item.getItemId match {
-    case R.id.share_app =>
-      val pm = getActivity.getPackageManager
-      val ai = pm.getInstalledApplications(0).find(_.sourceDir.contains(getActivity.getPackageName))
-      val intent = new Intent()
-      intent.setAction(Intent.ACTION_SEND)
-      intent.setType("*/*")
-      intent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(new File(ai.get.sourceDir)))
-      startActivity(intent)
-      true
-    case R.id.my_address =>
-      val prefs = PreferenceManager.getDefaultSharedPreferences(getActivity)
-      val fragment = new UserInfoFragment()
-      val bundle = new Bundle()
-      bundle.putString(
-        UserInfoFragment.ExtraAddress, ChatService.newCrypto(getActivity).localAddress.toString)
-      bundle.putString(
-        UserInfoFragment.ExtraUserName, prefs.getString(SettingsInterface.KeyUserName, ""))
-      fragment.setArguments(bundle)
-      fragment.show(getFragmentManager, "dialog")
-      true
-    case R.id.settings =>
-      startActivity(new Intent(getActivity, classOf[SettingsActivity]))
-      true
-    case _ =>
-      super.onOptionsItemSelected(item)
-  }
-
-  /**
-   * Opens a chat with the clicked device.
-   */
-  override def onListItemClick(l: ListView, v: View, position: Int, id: Long): Unit =
-    getActivity.asInstanceOf[MainActivity].openChat(adapter.getItem(position).address)
-
-  private val onContactsUpdatedListener = new BroadcastReceiver() {
-    override def onReceive(context: Context, intent: Intent): Unit = {
-      getActivity.runOnUiThread(new Runnable {
-        override def run(): Unit = {
-          adapter.clear()
-          database.getContacts.foreach(adapter.add)
-        }
-      })
-    }
-  }
-
-  private val onConnectionsChangedListener = new BroadcastReceiver {
-    override def onReceive(context: Context, intent: Intent): Unit = updateConnections()
-  }
-
-  /**
-   * Updates TextViews in actionbar with current connections.
-   */
-  private def updateConnections(): Unit = {
-    if (activity.service.isEmpty || title == null)
-      return
-
-    val service = activity.service.get
-    val connections = service.connections()
-    val count = connections.size
-    val color = count match {
-      case 0 => R.color.title_connections_error
-      case 1 => R.color.title_connections_warning
-      case _ => R.color.title_connections_ok
-    }
-
-    title.setText(getResources.getQuantityString(R.plurals.title_connections, count, count.toString))
-    title.setTextColor(ContextCompat.getColor(getActivity, color))
-
-    subtitle.setText(connections.map(service.getUser(_).name).mkString(", "))
-    subtitle.setVisibility(if (count == 0) View.GONE else View.VISIBLE)
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/fragments/SettingsFragment.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/fragments/SettingsFragment.scala
@ -1,60 +0,0 @@
-package com.nutomic.ensichat.fragments
-
-import android.content.SharedPreferences.OnSharedPreferenceChangeListener
-import android.content.{Intent, SharedPreferences}
-import android.os.Bundle
-import android.preference.{PreferenceFragment, PreferenceManager}
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.activities.EnsichatActivity
-import com.nutomic.ensichat.core.interfaces.SettingsInterface._
-import com.nutomic.ensichat.core.messages.body.UserInfo
-import com.nutomic.ensichat.fragments.SettingsFragment._
-import com.nutomic.ensichat.service.ChatService
-
-object SettingsFragment {
-  val Version = "version"
-}
-
-/**
- * Settings screen.
- */
-class SettingsFragment extends PreferenceFragment with OnSharedPreferenceChangeListener {
-
-  private lazy val activity = getActivity.asInstanceOf[EnsichatActivity]
-
-  private lazy val version = findPreference(Version)
-
-  private lazy val prefs = PreferenceManager.getDefaultSharedPreferences(getActivity)
-
-  override def onCreate(savedInstanceState: Bundle): Unit =  {
-    super.onCreate(savedInstanceState)
-
-    addPreferencesFromResource(R.xml.settings)
-
-    val packageInfo = getActivity.getPackageManager.getPackageInfo(getActivity.getPackageName, 0)
-    version.setSummary(packageInfo.versionName)
-    prefs.registerOnSharedPreferenceChangeListener(this)
-  }
-
-  override def onDestroy(): Unit = {
-    super.onDestroy()
-    prefs.unregisterOnSharedPreferenceChangeListener(this)
-  }
-
-  /**
-   * Sends the updated username or status to all contacts.
-   */
-  override def onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
-    key match {
-      case KeyUserName | KeyUserStatus =>
-        val ui = new UserInfo(prefs.getString(KeyUserName, ""), prefs.getString(KeyUserStatus, ""))
-        activity.database.get.getContacts.foreach(c =>  activity.service.get.sendTo(c.address, ui))
-      case KeyAddresses =>
-        val intent = new Intent(getActivity, classOf[ChatService])
-        intent.setAction(ChatService.ActionNetworkChanged)
-        getActivity.startService(intent)
-      case _ =>
-    }
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/fragments/UserInfoFragment.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/fragments/UserInfoFragment.scala
@ -1,86 +0,0 @@
-package com.nutomic.ensichat.fragments
-
-import android.app.{AlertDialog, Dialog, DialogFragment}
-import android.content.{ClipData, ClipboardManager, Context}
-import android.graphics.{Bitmap, Color}
-import android.os.Bundle
-import android.view.View.{OnClickListener, OnLongClickListener}
-import android.view.{LayoutInflater, View}
-import android.widget.{ImageView, TextView, Toast}
-import com.google.zxing.BarcodeFormat
-import com.google.zxing.common.BitMatrix
-import com.google.zxing.qrcode.QRCodeWriter
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.core.routing.Address
-import com.nutomic.ensichat.util.IdenticonGenerator
-
-object UserInfoFragment {
-  val ExtraAddress  = "address"
-  val ExtraUserName = "user_name"
-}
-
-/**
- * Displays identicon, username and address for a user.
- *
- * Use [[UserInfoFragment#getInstance]] to invoke.
- */
-class UserInfoFragment extends DialogFragment with OnLongClickListener {
-
-  private lazy val address  = new Address(getArguments.getString(UserInfoFragment.ExtraAddress))
-  private lazy val userName = getArguments.getString(UserInfoFragment.ExtraUserName)
-
-  override def onCreateDialog(savedInstanceState: Bundle): Dialog = {
-    val view = LayoutInflater.from(getActivity).inflate(R.layout.fragment_identicon, null)
-
-    view.findViewById(R.id.identicon)
-      .asInstanceOf[ImageView]
-      .setImageBitmap(IdenticonGenerator.generate(address, (150, 150), getActivity))
-    val addressTextView = view.findViewById(R.id.address)
-      .asInstanceOf[TextView]
-    addressTextView.setText(getString(R.string.address_colon, address.toString()))
-    addressTextView.setOnLongClickListener(this)
-    addressTextView.setOnClickListener(new OnClickListener {
-      override def onClick(v: View): Unit = onLongClick(v)
-    })
-
-    val matrix = new QRCodeWriter().encode(address.toString(), BarcodeFormat.QR_CODE, 150, 150)
-    view.findViewById(R.id.qr_code)
-      .asInstanceOf[ImageView]
-      .setImageBitmap(renderMatrix(matrix))
-
-    new AlertDialog.Builder(getActivity)
-      .setTitle(userName)
-      .setView(view)
-      .setPositiveButton(android.R.string.ok, null)
-      .create()
-  }
-
-  override def onLongClick(v: View): Boolean = {
-    val cm = getContext.getSystemService(Context.CLIPBOARD_SERVICE).asInstanceOf[ClipboardManager]
-    val clip = ClipData.newPlainText(getContext.getString(R.string.ensichat_user_address), address.toString)
-    cm.setPrimaryClip(clip)
-    Toast.makeText(getContext, R.string.address_copied_to_clipboard, Toast.LENGTH_SHORT).show()
-    true
-  }
-
-  /**
-   * Converts a [[BitMatrix]] instance into a [[Bitmap]].
-   */
-  private def renderMatrix(bitMatrix: BitMatrix): Bitmap = {
-    val height = bitMatrix.getHeight
-    val width = bitMatrix.getWidth
-    val bmp = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565)
-    for (x <- 0 until width) {
-      for (y <- 0 until height) {
-        val color =
-          if (bitMatrix.get(x,y))
-            Color.BLACK
-          else
-            Color.WHITE
-        bmp.setPixel(x, y, color)
-      }
-    }
-    bmp
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/service/BootReceiver.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/service/BootReceiver.scala
@ -1,16 +0,0 @@
-package com.nutomic.ensichat.service
-
-import android.content.{BroadcastReceiver, Context, Intent}
-import android.preference.PreferenceManager
-
-/**
- * Starts [[ChatService]] on boot if preference is enabled.
- */
-class BootReceiver extends BroadcastReceiver {
-
-  override def onReceive(context: Context, intent: Intent): Unit = {
-    val sp = PreferenceManager.getDefaultSharedPreferences(context)
-    context.startService(new Intent(context, classOf[ChatService]))
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/service/CallbackHandler.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/service/CallbackHandler.scala
@ -1,49 +0,0 @@
-package com.nutomic.ensichat.service
-
-import android.content.Intent
-import android.support.v4.content.LocalBroadcastManager
-import com.nutomic.ensichat.core.interfaces.CallbackInterface
-import com.nutomic.ensichat.core.ConnectionHandler
-import com.nutomic.ensichat.core.messages.Message
-import com.nutomic.ensichat.service.CallbackHandler._
-
-object CallbackHandler {
-
-  val ActionMessageReceived    = "message_received"
-  val ActionConnectionsChanged = "connections_changed"
-  val ActionContactsUpdated    = "contacts_updated"
-
-  val ExtraMessage             = "extra_message"
-
-}
-
-/**
- * Receives events from [[ConnectionHandler]] and sends them as local broadcasts.
- */
-class CallbackHandler(chatService: ChatService, notificationHandler: NotificationHandler)
-  extends CallbackInterface {
-
-  def onMessageReceived(msg: Message): Unit = {
-    notificationHandler.onMessageReceived(msg)
-    val i = new Intent(ActionMessageReceived)
-    i.putExtra(ExtraMessage, msg)
-    LocalBroadcastManager.getInstance(chatService)
-      .sendBroadcast(i)
-
-  }
-
-  def onConnectionsChanged(): Unit = {
-    val i = new Intent(ActionConnectionsChanged)
-    LocalBroadcastManager.getInstance(chatService)
-      .sendBroadcast(i)
-    notificationHandler
-      .updatePersistentNotification(chatService.getConnectionHandler.connections().size)
-  }
-
-  def onContactsUpdated(): Unit = {
-    val i = new Intent(ActionContactsUpdated)
-    LocalBroadcastManager.getInstance(chatService)
-      .sendBroadcast(i)
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/service/ChatService.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/service/ChatService.scala
@ -1,77 +0,0 @@
-package com.nutomic.ensichat.service
-
-import java.io.File
-
-import android.app.Service
-import android.bluetooth.BluetoothAdapter
-import android.content.{Context, Intent, IntentFilter}
-import android.net.ConnectivityManager
-import android.os.Handler
-import com.nutomic.ensichat.bluetooth.BluetoothInterface
-import com.nutomic.ensichat.core.interfaces.TransmissionInterface
-import com.nutomic.ensichat.core.util.{Crypto, Database}
-import com.nutomic.ensichat.core.ConnectionHandler
-import com.nutomic.ensichat.util.{NetworkChangedReceiver, SettingsWrapper}
-
-object ChatService {
-
-  case class Binder(service: ChatService) extends android.os.Binder
-
-  private def keyFolder(context: Context) = new File(context.getFilesDir, "keys")
-  def newCrypto(context: Context) = new Crypto(new SettingsWrapper(context), keyFolder(context))
-
-  val ActionNetworkChanged = "network_changed"
-
-}
-
-class ChatService extends Service {
-
-  private lazy val binder = new ChatService.Binder(this)
-
-  private lazy val notificationHandler = new NotificationHandler(this)
-
-  private val callbackHandler = new CallbackHandler(this, notificationHandler)
-
-  private def settingsWrapper = new SettingsWrapper(this)
-
-  lazy val database = new Database(getDatabasePath("database"), settingsWrapper, callbackHandler)
-
-  private lazy val connectionHandler =
-    new ConnectionHandler(settingsWrapper, database, callbackHandler, ChatService.newCrypto(this))
-
-  private val networkReceiver = new NetworkChangedReceiver()
-
-  override def onBind(intent: Intent) =  binder
-
-  override def onStartCommand(intent: Intent, flags: Int, startId: Int): Int = {
-    Option(intent).foreach { i =>
-      if (i.getAction == ChatService.ActionNetworkChanged)
-          connectionHandler.internetConnectionChanged()
-    }
-
-    Service.START_STICKY
-  }
-
-  /**
-   * Generates keys and starts Bluetooth interface.
-   */
-  override def onCreate(): Unit = {
-    super.onCreate()
-    notificationHandler.updatePersistentNotification(getConnectionHandler.connections().size)
-    var additionalInterfaces = Set[TransmissionInterface]()
-    if (Option(BluetoothAdapter.getDefaultAdapter).isDefined)
-      additionalInterfaces += new BluetoothInterface(this, new Handler(), connectionHandler)
-
-    connectionHandler.start(additionalInterfaces)
-    registerReceiver(networkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION))
-  }
-
-  override def onDestroy(): Unit = {
-    notificationHandler.stopPersistentNotification()
-    connectionHandler.stop()
-    unregisterReceiver(networkReceiver)
-  }
-
-  def getConnectionHandler = connectionHandler
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/service/NotificationHandler.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/service/NotificationHandler.scala
@ -1,91 +0,0 @@
-package com.nutomic.ensichat.service
-
-import android.app.{Notification, NotificationManager, PendingIntent}
-import android.content.{Context, Intent}
-import android.preference.PreferenceManager
-import android.support.v4.app.NotificationCompat
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.activities.MainActivity
-import com.nutomic.ensichat.core.messages.body.Text
-import com.nutomic.ensichat.core.interfaces.SettingsInterface
-import com.nutomic.ensichat.core.messages.Message
-import com.nutomic.ensichat.service.NotificationHandler._
-
-object NotificationHandler {
-
-  private val NotificationIdRunning = 1
-
-  private val NotificationIdNewMessage = 2
-
-}
-
-/**
- * Displays notifications for new messages and while the app is running.
- */
-class NotificationHandler(context: Context) {
-
-  private lazy val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE)
-    .asInstanceOf[NotificationManager]
-
-  private var persistentNotificationShutdown = false
-
-  def updatePersistentNotification(connections: Int): Unit = {
-    if (persistentNotificationShutdown)
-      return
-
-    val intent = PendingIntent.getActivity(context, 0, new Intent(context, classOf[MainActivity]), 0)
-    val info = context.getResources
-      .getQuantityString(R.plurals.notification_connections, connections, connections.toString)
-
-    val notification = new NotificationCompat.Builder(context)
-      .setSmallIcon(R.drawable.ic_launcher)
-      .setContentTitle(context.getString(R.string.app_name))
-      .setContentText(info)
-      .setContentIntent(intent)
-      .setOngoing(true)
-      .setPriority(Notification.PRIORITY_MIN)
-      .build()
-    notificationManager.notify(NotificationIdRunning, notification)
-  }
-
-  /**
-   * Cancels the persistent notification.
-   *
-   * After calling this method, [[updatePersistentNotification()]] will have no effect.
-   */
-  def stopPersistentNotification() = {
-    persistentNotificationShutdown = true
-    notificationManager.cancel(NotificationIdRunning)
-  }
-
-  def onMessageReceived(msg: Message): Unit = msg.body match {
-    case text: Text =>
-      if (msg.header.origin == ChatService.newCrypto(context).localAddress)
-        return
-
-      val pi = PendingIntent.getActivity(context, 0, new Intent(context, classOf[MainActivity]), 0)
-      val notification = new NotificationCompat.Builder(context)
-        .setSmallIcon(R.drawable.ic_launcher)
-        .setContentTitle(context.getString(R.string.notification_message))
-        .setContentText(text.text)
-        .setDefaults(defaults())
-        .setContentIntent(pi)
-        .setAutoCancel(true)
-        .build()
-
-      notificationManager.notify(NotificationIdNewMessage, notification)
-    case _ =>
-  }
-
-  /**
-   * Returns the default notification options that should be used.
-   */
-  private def defaults(): Int = {
-    val sp = PreferenceManager.getDefaultSharedPreferences(context)
-    if (sp.getBoolean(SettingsInterface.KeyNotificationSoundsOn, SettingsInterface.DefaultNotificationSoundsOn))
-      Notification.DEFAULT_ALL
-    else
-      Notification.DEFAULT_VIBRATE | Notification.DEFAULT_LIGHTS
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/util/NetworkChangedReceiver.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/util/NetworkChangedReceiver.scala
@ -1,31 +0,0 @@
-package com.nutomic.ensichat.util
-
-import android.content.{BroadcastReceiver, Context, Intent}
-import android.net.ConnectivityManager
-import com.nutomic.ensichat.service.ChatService
-
-/**
- * Forwards network changed intents to [[ChatService]].
- *
- * HACK: Because [[ConnectivityManager.CONNECTIVITY_ACTION]] is a sticky intent, and we register it
- *       from Scala, an intent is sent as soon as the receiver is registered. As a workaround, we
- *       ignore the first intent received.
- *       Alternatively, we can register the receiver in the manifest, but that will start the
- *       service (so it only works if the service runs permanently, with no exit).
- */
-class NetworkChangedReceiver extends BroadcastReceiver {
-
-  private var isFirstIntent = true
-
-  override def onReceive(context: Context, intent: Intent): Unit = {
-    if (isFirstIntent) {
-      isFirstIntent = false
-      return
-    }
-
-    val intent = new Intent(context, classOf[ChatService])
-    intent.setAction(ChatService.ActionNetworkChanged)
-    context.startService(intent)
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/util/SettingsWrapper.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/util/SettingsWrapper.scala
@ -1,23 +0,0 @@
-package com.nutomic.ensichat.util
-
-import android.content.Context
-import android.preference.PreferenceManager
-import com.nutomic.ensichat.core.interfaces.SettingsInterface
-
-class SettingsWrapper(context: Context) extends SettingsInterface {
-
-  private val prefs = PreferenceManager.getDefaultSharedPreferences(context)
-
-  override def get[T](key: String, default: T): T = default match {
-    case s: String => prefs.getString(key, s).asInstanceOf[T]
-    case i: Int    => prefs.getInt(key, i).asInstanceOf[T]
-    case l: Long   => prefs.getLong(key, l).asInstanceOf[T]
-  }
-
-  override def put[T](key: String, value: T): Unit = value match {
-    case s: String => prefs.edit().putString(key, s).apply()
-    case i: Int    => prefs.edit().putInt(key, i).apply()
-    case l: Long   => prefs.edit().putLong(key, l).apply()
-  }
-
-}
--- a/android/src/main/scala/com/nutomic/ensichat/views/DatesAdapter.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/views/DatesAdapter.scala
@ -1,37 +0,0 @@
-package com.nutomic.ensichat.views
-
-import java.text.DateFormat
-
-import android.content.Context
-import com.mobsandgeeks.adapters.{Sectionizer, SimpleSectionAdapter}
-import com.nutomic.ensichat.R
-import com.nutomic.ensichat.core.messages.Message
-
-import scala.collection.JavaConverters._
-
-object DatesAdapter {
-
-  private val Sectionizer = new Sectionizer[Message]() {
-    override def getSectionTitleForItem(item: Message): String = {
-      DateFormat
-        .getDateInstance(DateFormat.MEDIUM)
-        .format(item.header.time.get.toDate)
-    }
-  }
-
-}
-
-/**
- * Wraps [[MessagesAdapter]] and shows date between messages.
- */
-class DatesAdapter(context: Context, messagesAdapter: MessagesAdapter)
-  extends SimpleSectionAdapter[Message](context, messagesAdapter, R.layout.item_date, R.id.date,
-    DatesAdapter.Sectionizer) {
-
-  def replaceItems(items: Seq[Message]): Unit = {
-    messagesAdapter.clear()
-    messagesAdapter.addAll(items.asJava)
-    notifyDataSetChanged()
-  }
-
-}
--- a/android/.gitignore
+++ b/android/.gitignore
--- a/android/build.gradle
+++ b/android/build.gradle
@ -1,17 +1,24 @@
 apply plugin: 'com.android.application'
 apply plugin: 'jp.leafytree.android-scala'

+buildscript {
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        classpath "jp.leafytree.gradle:gradle-android-scala-plugin:1.4"
+    }
+}
+
 dependencies {
-    compile 'com.android.support:design:24.2.1'
+    compile "com.android.support:appcompat-v7:23.0.0"
    compile 'com.android.support:multidex:1.0.1'
-    compile 'org.scala-lang:scala-library:2.11.7'
+    androidTestCompile "com.android.support:multidex-instrumentation:1.0.1",
+                       { exclude module: "multidex" }
+    compile "org.scala-lang:scala-library:2.11.7"
+    compile 'com.google.guava:guava:18.0'
    compile 'com.mobsandgeeks:adapter-kit:0.5.3'
-    compile 'com.google.zxing:android-integration:3.3.0'
-    compile 'com.google.zxing:core:3.3.0'
-    compile 'org.slf4j:slf4j-android:1.7.21'
-    compile project(path: ':core')
-    androidTestCompile 'com.android.support:multidex-instrumentation:1.0.1',
-            { exclude module: 'multidex' }
+    // TODO: use @aar maven dependency for bitcoin
 }

 // RtlHardcoded behaviour differs between target API versions. We only care about API 15.
@ -25,23 +32,21 @@ preBuild.doFirst {
 }

 android {
-    compileSdkVersion 24
-    buildToolsVersion "24.0.2"
+    compileSdkVersion 23
+    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "com.nutomic.ensichat"
-        targetSdkVersion 24
-        versionCode 17
-        versionName "0.5.2"
+        targetSdkVersion 23
+        versionCode 7
+        versionName "0.1.6"
        multiDexEnabled true
        testInstrumentationRunner "com.android.test.runner.MultiDexTestRunner"
    }

-    buildTypes {
-        debug {
-            applicationIdSuffix ".debug"
-            testCoverageEnabled true
-        }
+    buildTypes.debug {
+        applicationIdSuffix ".debug"
+        testCoverageEnabled true
    }

    // Increasing minSdkVersion reduces compilation time for MultiDex.
--- a/android/lint.xml
+++ b/android/lint.xml
--- a/app/src/androidTest/scala/com/nutomic/ensichat/activities/MainActivityTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/activities/MainActivityTest.scala
@ -0,0 +1,39 @@
+package com.nutomic.ensichat.activities
+
+import android.bluetooth.BluetoothAdapter
+import android.content._
+import android.test.ActivityUnitTestCase
+import junit.framework.Assert
+
+class MainActivityTest extends ActivityUnitTestCase[MainActivity](classOf[MainActivity]) {
+
+  var lastIntent: Intent = _
+
+  class ActivityContextWrapper(context: Context) extends ContextWrapper(context) {
+    override def startService(service: Intent): ComponentName = {
+      lastIntent = service
+      null
+    }
+
+    override def stopService(name: Intent): Boolean = {
+      lastIntent = name
+      true
+    }
+
+    override def bindService(service: Intent, conn: ServiceConnection, flags: Int): Boolean = false
+
+    override def unbindService(conn: ServiceConnection): Unit = {}
+  }
+
+  override def setUp(): Unit = {
+    setActivityContext(new ActivityContextWrapper(getInstrumentation.getTargetContext))
+    startActivity(new Intent(), null, null)
+  }
+
+  def testRequestBluetoothDiscoverable(): Unit = {
+    val intent: Intent = getStartedActivityIntent
+    Assert.assertEquals(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE, intent.getAction)
+    Assert.assertEquals(0, intent.getIntExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, -1))
+  }
+
+}
--- a/android/src/androidTest/scala/com/nutomic/ensichat/bluetooth/BluetoothInterfaceTest.scala
+++ b/android/src/androidTest/scala/com/nutomic/ensichat/bluetooth/BluetoothInterfaceTest.scala
@ -6,18 +6,15 @@ import android.test.AndroidTestCase

 class BluetoothInterfaceTest extends AndroidTestCase {

-  private lazy val btInterface = new BluetoothInterface(getContext, new Handler(), null)
+  private lazy val adapter = new BluetoothInterface(getContext, new Handler(), Message => Unit, 
+    () => Unit, Message => false)

  /**
   * Test for issue [[https://github.com/Nutomic/ensichat/issues/3 #3]].
   */
  def testStartBluetoothOff(): Unit = {
-    val btAdapter = BluetoothAdapter.getDefaultAdapter
-    if (btAdapter == null)
-      return
-
-    btAdapter.disable()
-    btInterface.create()
+    BluetoothAdapter.getDefaultAdapter.disable()
+    adapter.create()
  }

 }
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/AddressTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/AddressTest.scala
@ -1,8 +1,8 @@
-package com.nutomic.ensichat.core.routing
+package com.nutomic.ensichat.protocol

-import com.nutomic.ensichat.core.routing.AddressTest._
-import junit.framework.TestCase
-import org.junit.Assert._
+import android.test.AndroidTestCase
+import com.nutomic.ensichat.protocol.AddressTest._
+import junit.framework.Assert._

 object AddressTest {

@ -24,7 +24,7 @@ object AddressTest {

 }

-class AddressTest extends TestCase {
+class AddressTest extends AndroidTestCase {

  def testEncode(): Unit = {
    Addresses.foreach{a =>
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/CryptoTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/CryptoTest.scala
@ -0,0 +1,35 @@
+package com.nutomic.ensichat.protocol
+
+import android.test.AndroidTestCase
+import junit.framework.Assert._
+
+class CryptoTest extends AndroidTestCase {
+
+  private lazy val crypto: Crypto = new Crypto(getContext)
+
+  override def setUp(): Unit = {
+    super.setUp()
+    if (!crypto.localKeysExist) {
+      crypto.generateLocalKeys()
+    }
+  }
+
+  def testSignVerify(): Unit = {
+    MessageTest.messages.foreach { m =>
+      val signed = crypto.sign(m)
+      assertTrue(crypto.verify(signed, crypto.getLocalPublicKey))
+      assertEquals(m.header, signed.header)
+      assertEquals(m.body, signed.body)
+    }
+  }
+
+  def testEncryptDecrypt(): Unit = {
+    MessageTest.messages.foreach{ m =>
+      val encrypted = crypto.encrypt(crypto.sign(m), crypto.getLocalPublicKey)
+      val decrypted = crypto.decrypt(encrypted)
+      assertEquals(m.body, decrypted.body)
+      assertEquals(m.header, encrypted.header)
+    }
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/MessageTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/MessageTest.scala
@ -0,0 +1,76 @@
+package com.nutomic.ensichat.protocol
+
+import java.io.ByteArrayInputStream
+
+import android.test.AndroidTestCase
+import com.nutomic.ensichat.protocol.MessageTest._
+import com.nutomic.ensichat.protocol.body.{ConnectionInfo, ConnectionInfoTest, Text}
+import com.nutomic.ensichat.protocol.header.ContentHeaderTest._
+import com.nutomic.ensichat.protocol.header.MessageHeader
+import junit.framework.Assert._
+
+import scala.collection.immutable.TreeSet
+
+object MessageTest {
+
+  val m1 = new Message(h1, new Text("first"))
+
+  val m2 = new Message(h2, new Text("second"))
+
+  val m3 = new Message(h3, new Text("third"))
+
+  val messages = Set(m1, m2, m3)
+
+}
+
+class MessageTest extends AndroidTestCase {
+
+  private lazy val crypto: Crypto = new Crypto(getContext)
+
+  override def setUp(): Unit = {
+    super.setUp()
+    if (!crypto.localKeysExist) {
+      crypto.generateLocalKeys()
+    }
+  }
+
+  def testOrder(): Unit = {
+    var messages = new TreeSet[Message]()(Message.Ordering)
+    messages += m1
+    messages += m2
+    assertEquals(m1, messages.firstKey)
+
+    messages = new TreeSet[Message]()(Message.Ordering)
+    messages += m2
+    messages += m3
+    assertEquals(m2, messages.firstKey)
+  }
+
+  def testSerializeSigned(): Unit = {
+    val header = new MessageHeader(ConnectionInfo.Type, AddressTest.a4, AddressTest.a2, 0)
+    val m = new Message(header, ConnectionInfoTest.generateCi(getContext))
+
+    val signed = crypto.sign(m)
+    val bytes = signed.write
+    val read = Message.read(new ByteArrayInputStream(bytes))
+
+    assertEquals(signed, read)
+    assertTrue(crypto.verify(read, crypto.getLocalPublicKey))
+  }
+
+  def testSerializeEncrypted(): Unit = {
+    MessageTest.messages.foreach{ m =>
+      val signed = crypto.sign(m)
+      val encrypted = crypto.encrypt(signed, crypto.getLocalPublicKey)
+      val bytes = encrypted.write
+
+      val read = Message.read(new ByteArrayInputStream(bytes))
+      assertEquals(encrypted.crypto, read.crypto)
+      val decrypted = crypto.decrypt(read)
+      assertEquals(m.header, decrypted.header)
+      assertEquals(m.body, decrypted.body)
+      assertTrue(crypto.verify(decrypted, crypto.getLocalPublicKey))
+    }
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/RouterTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/RouterTest.scala
@ -0,0 +1,106 @@
+package com.nutomic.ensichat.protocol
+
+import java.util.{Date, GregorianCalendar}
+
+import android.test.AndroidTestCase
+import com.nutomic.ensichat.protocol.body.{Text, UserInfo}
+import com.nutomic.ensichat.protocol.header.ContentHeader
+import junit.framework.Assert._
+
+class RouterTest extends AndroidTestCase {
+
+  private def neighbors() = Set[Address](AddressTest.a1, AddressTest.a2, AddressTest.a3)
+
+  private val msg = generateMessage(AddressTest.a1, AddressTest.a4, 1)
+
+  /**
+   * Messages should be sent to all neighbors.
+   */
+  def testFlooding(): Unit = {
+    var sentTo = Set[Address]()
+    val router: Router = new Router(neighbors,
+      (a, m) => {
+        sentTo += a
+      })
+
+    router.onReceive(msg)
+    assertEquals(neighbors(), sentTo)
+  }
+
+  def testMessageSame(): Unit = {
+    val router: Router = new Router(neighbors,
+      (a, m) => {
+        assertEquals(msg.header.origin,       m.header.origin)
+        assertEquals(msg.header.target,       m.header.target)
+        assertEquals(msg.header.seqNum,       m.header.seqNum)
+        assertEquals(msg.header.protocolType, m.header.protocolType)
+        assertEquals(msg.header.hopCount + 1, m.header.hopCount)
+        assertEquals(msg.header.hopLimit,     m.header.hopLimit)
+        assertEquals(msg.body, m.body)
+        assertEquals(msg.crypto, m.crypto)
+      })
+    router.onReceive(msg)
+  }
+
+  /**
+   * Messages from different senders with the same sequence number should be forwarded.
+   */
+  def testDifferentSenders(): Unit = {
+    var sentTo = Set[Address]()
+    val router: Router = new Router(neighbors, (a, m) => sentTo += a)
+
+    router.onReceive(msg)
+    assertEquals(neighbors(), sentTo)
+
+    sentTo = Set[Address]()
+    router.onReceive(generateMessage(AddressTest.a2, AddressTest.a4, 1))
+    assertEquals(neighbors(), sentTo)
+  }
+
+  /**
+   * Messages from the same sender with the same sequence number should be ignored.
+   */
+  def testIgnores(): Unit = {
+    var sentTo = Set[Address]()
+    val router: Router = new Router(neighbors, (a, m) => sentTo += a)
+
+    router.onReceive(msg)
+    assertEquals(neighbors(), sentTo)
+
+    sentTo = Set[Address]()
+    router.onReceive(generateMessage(AddressTest.a1, AddressTest.a2, 1))
+    assertTrue(sentTo.isEmpty)
+  }
+  
+  def testDiscardOldIgnores(): Unit = {
+    def test(first: Int, second: Int) {
+      var sentTo = Set[Address]()
+      val router: Router = new Router(neighbors, (a, m) => sentTo += a)
+      router.onReceive(generateMessage(AddressTest.a1, AddressTest.a3, first))
+      router.onReceive(generateMessage(AddressTest.a1, AddressTest.a3, second))
+
+      sentTo = Set[Address]()
+      router.onReceive(generateMessage(AddressTest.a1, AddressTest.a3, first))
+      assertEquals(neighbors(), sentTo)
+    }
+
+    test(1, ContentHeader.SeqNumRange.last)
+    test(ContentHeader.SeqNumRange.last / 2, ContentHeader.SeqNumRange.last)
+    test(ContentHeader.SeqNumRange.last / 2, 1)
+  }
+
+  def testHopLimit(): Unit = Range(19, 22).foreach { i =>
+    val header =
+      new ContentHeader(AddressTest.a1, AddressTest.a2, 1, 1, Some(1), Some(new Date()), false, i)
+    val msg = new Message(header, new Text(""))
+    val router: Router = new Router(neighbors, (a, m) => fail())
+    router.onReceive(msg)
+  }
+
+  private def generateMessage(sender: Address, receiver: Address, seqNum: Int): Message = {
+    val header = new ContentHeader(sender, receiver, seqNum, UserInfo.Type, Some(5),
+      Some(new GregorianCalendar(2014, 6, 10).getTime), false)
+    new Message(header, new UserInfo("", ""))
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/UserTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/UserTest.scala
@ -0,0 +1,11 @@
+package com.nutomic.ensichat.protocol
+
+object UserTest {
+
+  val u1 = new User(AddressTest.a1, "one", "s1")
+
+  val u2 = new User(AddressTest.a2, "two", "s2")
+
+  val u3 = new User(AddressTest.a3, "three", "s3")
+  
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/body/ConnectionInfoTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/body/ConnectionInfoTest.scala
@ -0,0 +1,28 @@
+package com.nutomic.ensichat.protocol.body
+
+import android.content.Context
+import android.test.AndroidTestCase
+import com.nutomic.ensichat.protocol.Crypto
+import junit.framework.Assert
+
+object ConnectionInfoTest {
+
+  def generateCi(context: Context) = {
+    val crypto = new Crypto(context)
+    if (!crypto.localKeysExist)
+      crypto.generateLocalKeys()
+    new ConnectionInfo(crypto.getLocalPublicKey)
+  }
+
+}
+
+class ConnectionInfoTest extends AndroidTestCase {
+
+  def testWriteRead(): Unit = {
+    val ci = ConnectionInfoTest.generateCi(getContext)
+    val bytes = ci.write
+    val body = ConnectionInfo.read(bytes)
+    Assert.assertEquals(ci, body)
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/body/PaymentInformationTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/body/PaymentInformationTest.scala
@ -0,0 +1,16 @@
+package com.nutomic.ensichat.protocol.body
+
+import android.test.AndroidTestCase
+import junit.framework.Assert
+
+
+class PaymentInformationTest extends AndroidTestCase {
+
+  def testWriteRead(): Unit = {
+    val pi = new PaymentInformation("testmessage".getBytes)
+    val bytes = pi.write
+    val body = PaymentInformation.read(bytes)
+    Assert.assertEquals(pi, body)
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/body/UserInfoTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/body/UserInfoTest.scala
@ -0,0 +1,15 @@
+package com.nutomic.ensichat.protocol.body
+
+import android.test.AndroidTestCase
+import junit.framework.Assert
+
+class UserInfoTest extends AndroidTestCase {
+
+  def testWriteRead(): Unit = {
+    val name = new UserInfo("name", "status")
+    val bytes = name.write
+    val body = UserInfo.read(bytes)
+    Assert.assertEquals(name, body.asInstanceOf[UserInfo])
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/header/ContentHeaderTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/header/ContentHeaderTest.scala
@ -0,0 +1,48 @@
+package com.nutomic.ensichat.protocol.header
+
+import java.util.{Date, GregorianCalendar}
+
+import android.test.AndroidTestCase
+import com.nutomic.ensichat.protocol.body.{PaymentInformation, Text}
+import com.nutomic.ensichat.protocol.{Address, AddressTest}
+import junit.framework.Assert._
+
+object ContentHeaderTest {
+
+  val h1 = new ContentHeader(AddressTest.a1, AddressTest.a2, 1234,
+    Text.Type, Some(123), Some(new GregorianCalendar(1970, 1, 1).getTime), false, 5)
+
+  val h2 = new ContentHeader(AddressTest.a1, AddressTest.a3,
+    30000, Text.Type, Some(8765), Some(new GregorianCalendar(2014, 6, 10).getTime), false, 20)
+
+  val h3 = new ContentHeader(AddressTest.a4, AddressTest.a2,
+    250, Text.Type, Some(77), Some(new GregorianCalendar(2020, 11, 11).getTime), false, 123)
+
+  val h4 = new ContentHeader(Address.Null, Address.Broadcast,
+    ContentHeader.SeqNumRange.last, 0, Some(0xffff), Some(new Date(0L)), false, 0xff)
+
+  val h5 = new ContentHeader(Address.Broadcast, Address.Null,
+    0, 0xff, Some(0), Some(new Date(0xffffffffL)), false, 0)
+
+  val h6 = new ContentHeader(AddressTest.a1, AddressTest.a2, 1234,
+    PaymentInformation.Type, Some(123), Some(new GregorianCalendar(2015, 8, 9).getTime), false, 5)
+
+  val headers = Set(h1, h2, h3, h4, h5, h6)
+
+}
+
+class ContentHeaderTest extends AndroidTestCase {
+
+  def testSerialize(): Unit = {
+    ContentHeaderTest.headers.foreach{h =>
+      val bytes = h.write(0)
+      assertEquals(bytes.length, h.length)
+      val (mh, length) = MessageHeader.read(bytes)
+      val chBytes = bytes.drop(mh.length)
+      val (header, remaining) = ContentHeader.read(mh, chBytes)
+      assertEquals(h, header)
+      assertEquals(0, remaining.length)
+    }
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/protocol/header/MessageHeaderTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/protocol/header/MessageHeaderTest.scala
@ -0,0 +1,33 @@
+package com.nutomic.ensichat.protocol.header
+
+import android.test.AndroidTestCase
+import com.nutomic.ensichat.protocol.header.MessageHeaderTest._
+import com.nutomic.ensichat.protocol.{Address, AddressTest}
+import junit.framework.Assert._
+
+object MessageHeaderTest {
+
+  val h1 = new MessageHeader(ContentHeader.ContentMessageType, AddressTest.a1, AddressTest.a2, 1234,
+    0)
+
+  val h2 = new MessageHeader(ContentHeader.ContentMessageType, Address.Null, Address.Broadcast,
+    ContentHeader.SeqNumRange.last, 0xff)
+
+  val h3 = new MessageHeader(ContentHeader.ContentMessageType, Address.Broadcast, Address.Null, 0)
+
+  val headers = Set(h1, h2, h3)
+
+}
+
+class MessageHeaderTest extends AndroidTestCase {
+
+  def testSerialize(): Unit = {
+    headers.foreach{h =>
+      val bytes = h.write(0)
+      val (header, length) = MessageHeader.read(bytes)
+      assertEquals(h, header)
+      assertEquals(MessageHeader.Length, length)
+    }
+  }
+
+}
--- a/app/src/androidTest/scala/com/nutomic/ensichat/util/DatabaseTest.scala
+++ b/app/src/androidTest/scala/com/nutomic/ensichat/util/DatabaseTest.scala
@ -0,0 +1,127 @@
+package com.nutomic.ensichat.util
+
+import java.util.concurrent.CountDownLatch
+
+import android.content._
+import android.database.DatabaseErrorHandler
+import android.database.sqlite.SQLiteDatabase
+import android.support.v4.content.LocalBroadcastManager
+import android.test.AndroidTestCase
+import com.nutomic.ensichat.protocol.MessageTest._
+import com.nutomic.ensichat.protocol.body.{CryptoData, PaymentInformation}
+import com.nutomic.ensichat.protocol.header.ContentHeader
+import com.nutomic.ensichat.protocol.header.ContentHeaderTest._
+import com.nutomic.ensichat.protocol.{AddressTest, Message, MessageTest, UserTest}
+import junit.framework.Assert._
+
+object DatabaseTest {
+
+  /**
+   * Provides a temporary database file that can be deleted easily.
+   */
+  class DatabaseContext(context: Context) extends ContextWrapper(context) {
+    private val dbFile = "database-test.db"
+    override def openOrCreateDatabase(file: String, mode: Int, factory:
+    SQLiteDatabase.CursorFactory, errorHandler: DatabaseErrorHandler): SQLiteDatabase = {
+      context.openOrCreateDatabase(dbFile, mode, factory, errorHandler)
+    }
+    def deleteDbFile() = context.deleteDatabase(dbFile)
+  }
+
+}
+
+class DatabaseTest extends AndroidTestCase {
+
+  private lazy val context = new DatabaseTest.DatabaseContext(getContext)
+
+  private lazy val database = new Database(context)
+
+  override def setUp(): Unit = {
+    super.setUp()
+    database.onMessageReceived(m1)
+    database.onMessageReceived(m2)
+    database.onMessageReceived(m3)
+  }
+
+  override def tearDown(): Unit = {
+    super.tearDown()
+    database.close()
+    context.deleteDbFile()
+  }
+
+  def testMessageCount(): Unit = {
+    val msg1 = database.getMessages(m1.header.origin, 1)
+    assertEquals(1, msg1.size)
+
+    val msg2 = database.getMessages(m1.header.origin, 3)
+    assertEquals(2, msg2.size)
+  }
+
+  def testMessageOrder(): Unit = {
+    val msg = database.getMessages(m1.header.target, 1)
+    assertTrue(msg.contains(m1))
+  }
+
+  def testMessageSelect(): Unit = {
+    val msg = database.getMessages(m1.header.target, 2)
+    assertTrue(msg.contains(m1))
+    assertTrue(msg.contains(m3))
+  }
+
+  def testTextMessage(): Unit = {
+    val msg = database.getMessages(m3.header.target, 1).firstKey
+    val header = msg.header.asInstanceOf[ContentHeader]
+
+    assertEquals(h2.origin, header.origin)
+    assertEquals(h2.target, header.target)
+    assertEquals(-1, msg.header.seqNum)
+    assertEquals(h3.contentType, header.contentType)
+    assertEquals(h3.messageId, header.messageId)
+    assertEquals(h3.time, header.time)
+    assertEquals(h3.read, header.read)
+    assertEquals(new CryptoData(None, None), msg.crypto)
+    assertEquals(m3.body, msg.body)
+  }
+
+  def testPaymentRequestMessage(): Unit = {
+    val pr = new PaymentInformation("teststring".getBytes)
+    val msg = new Message(h6, pr)
+    database.onMessageReceived(msg)
+    val retrieved = database.getMessages(h6.origin, 1).firstKey
+    assertEquals(pr, retrieved.body)
+  }
+
+  def testMessageRead(): Unit = {
+    database.setMessageRead(h3)
+    val header = database.getMessages(AddressTest.a4, 1).firstKey.header.asInstanceOf[ContentHeader]
+    assertTrue(header.read)
+  }
+
+  def testAddContact(): Unit = {
+    database.addContact(UserTest.u1)
+    val contacts = database.getContacts
+    assertEquals(1, contacts.size)
+    assertEquals(Option(UserTest.u1), database.getContact(UserTest.u1.address))
+  }
+
+  def testAddContactCallback(): Unit = {
+    val latch = new CountDownLatch(1)
+    val lbm = LocalBroadcastManager.getInstance(context)
+    val receiver = new BroadcastReceiver {
+      override def onReceive(context: Context, intent: Intent): Unit = latch.countDown()
+    }
+    lbm.registerReceiver(receiver, new IntentFilter(Database.ActionContactsUpdated))
+    database.addContact(UserTest.u1)
+    latch.await()
+    lbm.unregisterReceiver(receiver)
+  }
+  
+  def testGetContact(): Unit = {
+    database.addContact(UserTest.u2)
+    assertTrue(database.getContact(UserTest.u1.address).isEmpty)
+    val c = database.getContact(UserTest.u2.address)
+    assertTrue(c.nonEmpty)
+    assertEquals(Option(UserTest.u2), c)
+  }
+
+}
--- a/android/src/main/AndroidManifest.xml
+++ b/android/src/main/AndroidManifest.xml
@ -6,15 +6,11 @@

    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
-    <uses-permission android:name="android.permission.INTERNET" />
-    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
-    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
-    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

-    <uses-feature android:name="android.hardware.bluetooth" android:required="false" />
+    <uses-feature android:name="android.hardware.bluetooth" android:required="true" />

    <application
-        android:name=".App"
+        android:name="android.support.multidex.MultiDexApplication"
        android:allowBackup="true"
        android:fullBackupContent="true"
        android:icon="@drawable/ic_launcher"
@ -34,13 +30,11 @@
        <activity
            android:name=".activities.MainActivity"
            android:label="@string/app_name"
-            android:launchMode="singleTop"
-            android:theme="@style/AppTheme.NoActionBar"/>
+            android:launchMode="singleTop" />

        <activity
-            android:name=".activities.ConnectionsActivity"
-            android:label="@string/connections"
-            android:parentActivityName=".activities.MainActivity">
+            android:name=".activities.AddContactsActivity"
+            android:label="@string/add_contacts" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".activities.MainActivity" />
@ -48,20 +42,13 @@

        <activity
            android:name=".activities.SettingsActivity"
-            android:label="@string/settings"
-            android:parentActivityName=".activities.MainActivity">
+            android:label="@string/settings" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".activities.MainActivity" />
        </activity>

-        <receiver android:name=".service.BootReceiver">
-            <intent-filter>
-                <action android:name="android.intent.action.BOOT_COMPLETED"/>
-            </intent-filter>
-        </receiver>
-
-        <service android:name=".service.ChatService" />
+        <service android:name=".protocol.ChatService" />

    </application>

--- a/android/src/main/java/com/nutomic/ensichat/util/PRNGFixes.java
+++ b/android/src/main/java/com/nutomic/ensichat/util/PRNGFixes.java
--- a/app/src/main/java/de/schildbach/wallet/integration/android/BitcoinIntegration.java
+++ b/app/src/main/java/de/schildbach/wallet/integration/android/BitcoinIntegration.java
@ -0,0 +1,284 @@
+/**
+ * Copyright 2012-2014 the original author or authors.
+ *
+ * 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 de.schildbach.wallet.integration.android;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.net.Uri;
+import android.widget.Toast;
+
+/**
+ * @author Andreas Schildbach
+ */
+public final class BitcoinIntegration
+{
+    private static final String INTENT_EXTRA_PAYMENTREQUEST = "paymentrequest";
+    private static final String INTENT_EXTRA_PAYMENT = "payment";
+    private static final String INTENT_EXTRA_TRANSACTION_HASH = "transaction_hash";
+
+    private static final String MIMETYPE_PAYMENTREQUEST = "application/bitcoin-paymentrequest"; // BIP 71
+
+    /**
+     * Request any amount of Bitcoins (probably a donation) from user, without feedback from the app.
+     *
+     * @param context
+     *            Android context
+     * @param address
+     *            Bitcoin address
+     */
+    public static void request(final Context context, final String address)
+    {
+        final Intent intent = makeBitcoinUriIntent(address, null);
+
+        start(context, intent);
+    }
+
+    /**
+     * Request specific amount of Bitcoins from user, without feedback from the app.
+     *
+     * @param context
+     *            Android context
+     * @param address
+     *            Bitcoin address
+     * @param amount
+     *            Bitcoin amount in satoshis
+     */
+    public static void request(final Context context, final String address, final long amount)
+    {
+        final Intent intent = makeBitcoinUriIntent(address, amount);
+
+        start(context, intent);
+    }
+
+    /**
+     * Request payment from user, without feedback from the app.
+     *
+     * @param context
+     *            Android context
+     * @param paymentRequest
+     *            BIP70 formatted payment request
+     */
+    public static void request(final Context context, final byte[] paymentRequest)
+    {
+        final Intent intent = makePaymentRequestIntent(paymentRequest);
+
+        start(context, intent);
+    }
+
+    /**
+     * Request any amount of Bitcoins (probably a donation) from user, with feedback from the app. Result intent can be
+     * received by overriding {@link android.app.Activity#onActivityResult()}. Result indicates either
+     * {@link Activity#RESULT_OK} or {@link Activity#RESULT_CANCELED}. In the success case, use
+     * {@link #transactionHashFromResult(Intent)} to read the transaction hash from the intent.
+     *
+     * Warning: A success indication is no guarantee! To be on the safe side, you must drive your own Bitcoin
+     * infrastructure and validate the transaction.
+     *
+     * @param activity
+     *            Calling Android activity
+     * @param requestCode
+     *            Code identifying the call when {@link android.app.Activity#onActivityResult()} is called back
+     * @param address
+     *            Bitcoin address
+     */
+    public static void requestForResult(final Activity activity, final int requestCode, final String address)
+    {
+        final Intent intent = makeBitcoinUriIntent(address, null);
+
+        startForResult(activity, requestCode, intent);
+    }
+
+    /**
+     * Request specific amount of Bitcoins from user, with feedback from the app. Result intent can be received by
+     * overriding {@link android.app.Activity#onActivityResult()}. Result indicates either {@link Activity#RESULT_OK} or
+     * {@link Activity#RESULT_CANCELED}. In the success case, use {@link #transactionHashFromResult(Intent)} to read the
+     * transaction hash from the intent.
+     *
+     * Warning: A success indication is no guarantee! To be on the safe side, you must drive your own Bitcoin
+     * infrastructure and validate the transaction.
+     *
+     * @param activity
+     *            Calling Android activity
+     * @param requestCode
+     *            Code identifying the call when {@link android.app.Activity#onActivityResult()} is called back
+     * @param address
+     *            Bitcoin address
+     */
+    public static void requestForResult(final Activity activity, final int requestCode, final String address, final long amount)
+    {
+        final Intent intent = makeBitcoinUriIntent(address, amount);
+
+        startForResult(activity, requestCode, intent);
+    }
+
+    /**
+     * Request payment from user, with feedback from the app. Result intent can be received by overriding
+     * {@link android.app.Activity#onActivityResult()}. Result indicates either {@link Activity#RESULT_OK} or
+     * {@link Activity#RESULT_CANCELED}. In the success case, use {@link #transactionHashFromResult(Intent)} to read the
+     * transaction hash from the intent.
+     *
+     * Warning: A success indication is no guarantee! To be on the safe side, you must drive your own Bitcoin
+     * infrastructure and validate the transaction.
+     *
+     * @param activity
+     *            Calling Android activity
+     * @param requestCode
+     *            Code identifying the call when {@link android.app.Activity#onActivityResult()} is called back
+     * @param paymentRequest
+     *            BIP70 formatted payment request
+     */
+    public static void requestForResult(final Activity activity, final int requestCode, final byte[] paymentRequest)
+    {
+        final Intent intent = makePaymentRequestIntent(paymentRequest);
+
+        startForResult(activity, requestCode, intent);
+    }
+
+    /**
+     * Get payment request from intent. Meant for usage by applications accepting payment requests.
+     *
+     * @param intent
+     *            intent
+     * @return payment request or null
+     */
+    public static byte[] paymentRequestFromIntent(final Intent intent)
+    {
+        final byte[] paymentRequest = intent.getByteArrayExtra(INTENT_EXTRA_PAYMENTREQUEST);
+
+        return paymentRequest;
+    }
+
+    /**
+     * Put BIP70 payment message into result intent. Meant for usage by Bitcoin wallet applications.
+     *
+     * @param result
+     *            result intent
+     * @param payment
+     *            payment message
+     */
+    public static void paymentToResult(final Intent result, final byte[] payment)
+    {
+        result.putExtra(INTENT_EXTRA_PAYMENT, payment);
+    }
+
+    /**
+     * Get BIP70 payment message from result intent. Meant for usage by applications initiating a Bitcoin payment.
+     *
+     * You can use the transactions contained in the payment to validate the payment. For this, you need your own
+     * Bitcoin infrastructure though. There is no guarantee that the payment will ever confirm.
+     *
+     * @param result
+     *            result intent
+     * @return payment message
+     */
+    public static byte[] paymentFromResult(final Intent result)
+    {
+        final byte[] payment = result.getByteArrayExtra(INTENT_EXTRA_PAYMENT);
+
+        return payment;
+    }
+
+    /**
+     * Put transaction hash into result intent. Meant for usage by Bitcoin wallet applications.
+     *
+     * @param result
+     *            result intent
+     * @param txHash
+     *            transaction hash
+     */
+    public static void transactionHashToResult(final Intent result, final String txHash)
+    {
+        result.putExtra(INTENT_EXTRA_TRANSACTION_HASH, txHash);
+    }
+
+    /**
+     * Get transaction hash from result intent. Meant for usage by applications initiating a Bitcoin payment.
+     *
+     * You can use this hash to request the transaction from the Bitcoin network, in order to validate. For this, you
+     * need your own Bitcoin infrastructure though. There is no guarantee that the transaction has ever been broadcasted
+     * to the Bitcoin network.
+     *
+     * @param result
+     *            result intent
+     * @return transaction hash
+     */
+    public static String transactionHashFromResult(final Intent result)
+    {
+        final String txHash = result.getStringExtra(INTENT_EXTRA_TRANSACTION_HASH);
+
+        return txHash;
+    }
+
+    private static final int SATOSHIS_PER_COIN = 100000000;
+
+    private static Intent makeBitcoinUriIntent(final String address, final Long amount)
+    {
+        final StringBuilder uri = new StringBuilder("bitcoin:");
+        if (address != null)
+            uri.append(address);
+        if (amount != null)
+            uri.append("?amount=").append(String.format("%d.%08d", amount / SATOSHIS_PER_COIN, amount % SATOSHIS_PER_COIN));
+
+        final Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri.toString()));
+
+        return intent;
+    }
+
+    private static Intent makePaymentRequestIntent(final byte[] paymentRequest)
+    {
+        final Intent intent = new Intent(Intent.ACTION_VIEW);
+        intent.setType(MIMETYPE_PAYMENTREQUEST);
+        intent.putExtra(INTENT_EXTRA_PAYMENTREQUEST, paymentRequest);
+
+        return intent;
+    }
+
+    private static void start(final Context context, final Intent intent)
+    {
+        final PackageManager pm = context.getPackageManager();
+        if (pm.resolveActivity(intent, 0) != null)
+            context.startActivity(intent);
+        else
+            redirectToDownload(context);
+    }
+
+    private static void startForResult(final Activity activity, final int requestCode, final Intent intent)
+    {
+        final PackageManager pm = activity.getPackageManager();
+        if (pm.resolveActivity(intent, 0) != null)
+            activity.startActivityForResult(intent, requestCode);
+        else
+            redirectToDownload(activity);
+    }
+
+    private static void redirectToDownload(final Context context)
+    {
+        Toast.makeText(context, "No Bitcoin application found.\nPlease install Bitcoin Wallet.", Toast.LENGTH_LONG).show();
+
+        final Intent marketIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=de.schildbach.wallet"));
+        final Intent binaryIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("https://github.com/schildbach/bitcoin-wallet/releases"));
+
+        final PackageManager pm = context.getPackageManager();
+        if (pm.resolveActivity(marketIntent, 0) != null)
+            context.startActivity(marketIntent);
+        else if (pm.resolveActivity(binaryIntent, 0) != null)
+            context.startActivity(binaryIntent);
+        // else out of luck
+    }
+}
--- a/app/src/main/res/drawable-hdpi/ic_action_add_person.png
+++ b/app/src/main/res/drawable-hdpi/ic_action_add_person.png
--- a/android/src/main/res/drawable-hdpi/ic_action_send_now.png
+++ b/android/src/main/res/drawable-hdpi/ic_action_send_now.png
--- a/app/src/main/res/drawable-hdpi/ic_bitcoin.png
+++ b/app/src/main/res/drawable-hdpi/ic_bitcoin.png
--- a/app/src/main/res/drawable-hdpi/ic_launcher.png
+++ b/app/src/main/res/drawable-hdpi/ic_launcher.png
--- a/app/src/main/res/drawable-mdpi/ic_action_add_person.png
+++ b/app/src/main/res/drawable-mdpi/ic_action_add_person.png
--- a/android/src/main/res/drawable-mdpi/ic_action_send_now.png
+++ b/android/src/main/res/drawable-mdpi/ic_action_send_now.png
--- a/app/src/main/res/drawable-mdpi/ic_bitcoin.png
+++ b/app/src/main/res/drawable-mdpi/ic_bitcoin.png
--- a/app/src/main/res/drawable-mdpi/ic_launcher.png
+++ b/app/src/main/res/drawable-mdpi/ic_launcher.png
--- a/app/src/main/res/drawable-xhdpi/ic_action_add_person.png
+++ b/app/src/main/res/drawable-xhdpi/ic_action_add_person.png
--- a/android/src/main/res/drawable-xhdpi/ic_action_send_now.png
+++ b/android/src/main/res/drawable-xhdpi/ic_action_send_now.png
--- a/app/src/main/res/drawable-xhdpi/ic_bitcoin.png
+++ b/app/src/main/res/drawable-xhdpi/ic_bitcoin.png
--- a/app/src/main/res/drawable-xhdpi/ic_launcher.png
+++ b/app/src/main/res/drawable-xhdpi/ic_launcher.png
--- a/app/src/main/res/drawable-xxhdpi/ic_action_add_person.png
+++ b/app/src/main/res/drawable-xxhdpi/ic_action_add_person.png
--- a/android/src/main/res/drawable-xxhdpi/ic_action_send_now.png
+++ b/android/src/main/res/drawable-xxhdpi/ic_action_send_now.png
--- a/app/src/main/res/drawable-xxhdpi/ic_bitcoin.png
+++ b/app/src/main/res/drawable-xxhdpi/ic_bitcoin.png
--- a/app/src/main/res/drawable-xxhdpi/ic_launcher.png
+++ b/app/src/main/res/drawable-xxhdpi/ic_launcher.png
--- a/android/src/main/res/drawable/message_background.xml
+++ b/android/src/main/res/drawable/message_background.xml
--- a/android/src/main/res/layout/activity_connections.xml
+++ b/android/src/main/res/layout/activity_connections.xml
@ -26,7 +26,7 @@
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
-            android:text="@string/no_connections"
+            android:text="@string/devices_empty"
            android:gravity="center" />

    </LinearLayout>
--- a/android/src/main/res/layout/activity_first_start.xml
+++ b/android/src/main/res/layout/activity_first_start.xml
--- a/android/src/main/res/layout/activity_main.xml
+++ b/android/src/main/res/layout/activity_main.xml
@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>

-
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/primary"
    android:layout_width="fill_parent"
--- a/android/src/main/res/layout/fragment_chat.xml
+++ b/android/src/main/res/layout/fragment_chat.xml
@ -1,28 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_weight="10"
    android:orientation="vertical"
    android:background="@color/chat_background">

-
-    <android.support.design.widget.AppBarLayout
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content">
-
-        <android.support.v7.widget.Toolbar
-            android:id="@+id/toolbar"
-            android:layout_height="?attr/actionBarSize"
-            android:layout_width="match_parent"
-            android:background="?attr/colorPrimary"
-            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
-            app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
-
-    </android.support.design.widget.AppBarLayout>
-
    <FrameLayout
        android:layout_height="0dp"
        android:layout_width="match_parent"
@ -52,13 +36,18 @@
        android:id="@+id/linearLayout"
        android:orientation="horizontal">

+        <ImageButton
+            android:layout_width="45dp"
+            android:layout_height="45dp"
+            android:id="@+id/send_bitcoin"
+            android:src="@drawable/ic_bitcoin"
+            android:background="@android:color/transparent"/>
+
        <EditText
            android:id="@+id/message"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
-            android:hint="@string/message_hint"
-            android:textColorHint="#cccccc"
            android:imeOptions="actionDone"
            android:inputType="textMultiLine|textCapSentences|textAutoCorrect"/>

--- a/app/src/main/res/layout/fragment_contacts.xml
+++ b/app/src/main/res/layout/fragment_contacts.xml
@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent" >
+
+    <ListView
+        android:id="@android:id/list"
+        android:layout_width="fill_parent"
+        android:layout_height="fill_parent" />
+
+    <TextView
+        android:id="@android:id/empty"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/no_contacts_found"
+        android:layout_centerHorizontal="true"
+        android:layout_centerVertical="true" />
+
+</RelativeLayout>
--- a/app/src/main/res/layout/fragment_identicon.xml
+++ b/app/src/main/res/layout/fragment_identicon.xml
@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:gravity="center"
+    android:padding="25dp">
+
+    <ImageView
+        android:id="@+id/identicon"
+        android:layout_width="150dp"
+        android:layout_height="150dp"
+        android:layout_marginBottom="25dp" />
+
+    <TextView
+        android:id="@+id/address"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content" />
+
+</LinearLayout>
--- a/android/src/main/res/layout/item_date.xml
+++ b/android/src/main/res/layout/item_date.xml
--- a/android/src/main/res/layout/item_message.xml
+++ b/android/src/main/res/layout/item_message.xml
--- a/android/src/main/res/layout/item_user.xml
+++ b/android/src/main/res/layout/item_user.xml
--- a/android/src/main/res/menu/main.xml
+++ b/android/src/main/res/menu/main.xml
@ -1,6 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>

-<menu xmlns:android="http://schemas.android.com/apk/res/android">
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <item
+        android:id="@+id/add_contact"
+        android:title="@string/add_contacts"
+        android:icon="@drawable/ic_action_add_person"
+        app:showAsAction="ifRoom" />

    <item
        android:id="@+id/share_app"
@ -14,4 +21,8 @@
        android:id="@+id/settings"
        android:title="@string/settings" />

+    <item
+        android:id="@+id/exit"
+        android:title="@string/exit" />
+
 </menu>
--- a/android/src/main/res/values/colors.xml
+++ b/android/src/main/res/values/colors.xml
@ -14,8 +14,4 @@
    <!-- Background color for ChatFragment -->
    <color name="chat_background">#f3f2fb</color>

-    <color name="title_connections_error">#F44336</color>
-    <color name="title_connections_warning">#FFEB3B</color>
-    <color name="title_connections_ok">#8BC34A</color>
-
 </resources>
--- a/app/src/main/res/values/settings_defaults.xml
+++ b/app/src/main/res/values/settings_defaults.xml
@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources translatable="false">
+
+    <string name="default_user_status">Let\'s chat!</string>
+
+    <bool name="default_notification_sounds">true</bool>
+
+    <string name="default_scan_interval">15</string>
+
+    <string name="default_max_connections">1000000</string>
+
+    <string-array name="bitcoin_wallets">
+        <item>de.schildbach.wallet</item>
+        <item>de.schildbach.wallet_test</item>
+    </string-array>
+
+    <string name="default_bitcoin_wallet">de.schildbach.wallet</string>
+
+</resources>
--- a/android/src/main/res/values/strings.xml
+++ b/android/src/main/res/values/strings.xml
@ -18,42 +18,32 @@
    <!-- Label for button to finish activity -->
    <string name="done">Done</string>

-    <!-- Toast shown if location permission is not granted -->
-    <string name="toast_location_required">Location permission is required to scan for other Bluetooth devices</string>

    <!-- MainActivity -->

    <!-- Toast shown if user denies request to enable bluetooth -->
-    <string name="toast_bluetooth_denied">Please enable Bluetooth to connect with devices near you</string>
+    <string name="bluetooth_required">Bluetooth is required for this app.</string>


    <!-- ContactsFragment -->

-    <!-- Number of connections shown in actionbar -->
-    <plurals name="title_connections">
-        <item quantity="one">1 Connection</item>
-        <item quantity="other">%s Connections</item>
-    </plurals>
-
    <!-- Empty text for contacts list -->
    <string name="no_contacts_found">You haven\'t added any contacts yet</string>

    <!-- Menu item to share this app's apk -->
    <string name="share_app">Share App</string>

-    <!-- ChatFragment -->
-
-    <!-- Hint text for the message EditText -->
-    <string name="message_hint">Type a message</string>
+    <!-- Menu item to close app and stop service -->
+    <string name="exit">Exit</string>


-    <!-- ConnectionsActivity -->
+    <!-- AddContactsActivity -->

    <!-- Activity title -->
-    <string name="connections">Connections</string>
+    <string name="add_contacts">Add Contacts</string>

    <!-- Empty text for devices list -->
-    <string name="no_connections">Searching for Users\nRange: ~10m</string>
+    <string name="devices_empty">Searching for Users\nRange: ~10m</string>

    <!-- Alertdialog message to add new contact -->
    <string name="dialog_add_contact">Do you want to add %1$s as contact?</string>
@ -61,16 +51,10 @@
    <!-- Toast shown after contact has been added -->
    <string name="toast_contact_added">Contact added</string>

-    <!-- Toast shown when clicking a user that is already a contact -->
-    <string name="contact_already_added">You have already added %1$s as a contact</string>

-    <string name="enter_id">Enter user ID</string>
+    <!-- ChatFragment -->

-    <string name="invalid_address">Invalid address</string>
-
-    <string name="add_contact">Add Contact</string>
-
-    <string name="scan_qr_code">Scan QR-Code</string>
+    <string name="bitcoin_wallet_not_found">Bitcoin wallet not found. Please install wallet app or select another wallet in the app settings.</string>


    <!-- SettingsActivity -->
@ -93,8 +77,16 @@
    <!-- Preference title -->
    <string name="notification_sounds">Notification Sounds</string>

-    <!-- Preference title -->
-    <string name="servers">Servers</string>
+    <string name="bitcoin_wallet">Bitcoin Wallet Application</string>
+
+    <!-- List of supported wallet apps -->
+    <string-array name="bitcoin_wallet_values">
+        <item>Bitcoin Wallet</item>
+        <item>Bitcoin Wallet for Testnet</item>
+    </string-array>
+
+    <!-- Preference title (debug only)-->
+    <string name="max_connections" translatable="false">Maximum Number of Connections</string>

    <!-- Preference title -->
    <string name="report_issue">Report Issue</string>
@ -107,26 +99,15 @@
    <!-- Preference title -->
    <string name="version">Version</string>

-
-    <!-- UserInfoFragment -->
+    <!-- IdenticonFragment -->

    <!-- Device address label and value -->
    <string name="address_colon">Address: %1$s</string>

-    <string name="ensichat_user_address">Ensichat User Address</string>
-
-    <string name="address_copied_to_clipboard">Address copied to clipboard</string>
-

    <!-- ChatService -->

    <!-- Notification text for incoming message -->
    <string name="notification_message">New message!</string>

-    <!-- Info text for persistent notification -->
-    <plurals name="notification_connections">
-        <item quantity="one">Connected to %1$s device</item>
-        <item quantity="other">Connected to %1$s devices</item>
-    </plurals>
-
 </resources>
--- a/android/src/main/res/values/style.xml
+++ b/android/src/main/res/values/style.xml
@ -9,11 +9,6 @@
        <item name="android:alertDialogTheme">@style/AlertDialogTheme</item>
    </style>

-    <style name="AppTheme.NoActionBar" parent="AppTheme">
-        <item name="windowActionBar">false</item>
-        <item name="windowNoTitle">true</item>
-    </style>
-
    <style name="AlertDialogTheme" parent="@style/Theme.AppCompat.Light.Dialog">
        <item name="colorPrimary">@color/primary</item>
        <item name="colorPrimaryDark">@color/primary_dark</item>
--- a/android/src/main/res/xml/settings.xml
+++ b/android/src/main/res/xml/settings.xml
@ -4,27 +4,37 @@

    <EditTextPreference
        android:title="@string/user_name"
-        android:key="user_name"
-        android:inputType="textCapWords"/>
+        android:key="user_name" />

    <EditTextPreference
        android:title="@string/user_status"
-        android:key="user_status"
-        android:inputType="textCapSentences" />
+        android:key="user_status" />

    <CheckBoxPreference
        android:title="@string/notification_sounds"
-        android:key="notification_sounds" />
+        android:key="notification_sounds"
+        android:defaultValue="@bool/default_notification_sounds" />

    <EditTextPreference
        android:title="@string/scan_interval_seconds"
        android:key="scan_interval_seconds"
+        android:defaultValue="@string/default_scan_interval"
        android:inputType="number"
        android:numeric="integer" />

+    <ListPreference
+        android:title="@string/bitcoin_wallet"
+        android:key="bitcoin_wallet"
+        android:entries="@array/bitcoin_wallet_values"
+        android:entryValues="@array/bitcoin_wallets"
+        android:defaultValue="@string/default_bitcoin_wallet" />
+
    <EditTextPreference
-        android:title="@string/servers"
-        android:key="servers" />
+        android:title="@string/max_connections"
+        android:key="max_connections"
+        android:defaultValue="@string/default_max_connections"
+        android:inputType="number"
+        android:numeric="integer" />

    <Preference
        android:title="@string/report_issue"
@ -36,6 +46,7 @@

    <Preference
        android:title="@string/version"
-        android:key="version" />
+        android:key="version"
+        style="?android:preferenceInformationStyle" />

 </PreferenceScreen>
--- a/app/src/main/scala/com/nutomic/ensichat/activities/AddContactsActivity.scala
+++ b/app/src/main/scala/com/nutomic/ensichat/activities/AddContactsActivity.scala
@ -0,0 +1,94 @@
+package com.nutomic.ensichat.activities
+
+import android.app.AlertDialog.Builder
+import android.content.DialogInterface.OnClickListener
+import android.content._
+import android.os.Bundle
+import android.support.v4.app.NavUtils
+import android.support.v4.content.LocalBroadcastManager
+import android.view._
+import android.widget.AdapterView.OnItemClickListener
+import android.widget._
+import com.nutomic.ensichat.R
+import com.nutomic.ensichat.protocol.ChatService
+import com.nutomic.ensichat.util.Database
+import com.nutomic.ensichat.views.UsersAdapter
+
+/**
+ * Lists all nearby, connected devices and allows adding them to be added as contacts.
+ */
+class AddContactsActivity extends EnsichatActivity with OnItemClickListener {
+
+  private val Tag = "AddContactsActivity"
+
+  private lazy val database = new Database(this)
+
+  private lazy val adapter = new UsersAdapter(this)
+
+  /**
+   * Initializes layout, registers connection and message listeners.
+   */
+  override def onCreate(savedInstanceState: Bundle): Unit = {
+    super.onCreate(savedInstanceState)
+    getSupportActionBar.setDisplayHomeAsUpEnabled(true)
+
+    setContentView(R.layout.activity_add_contacts)
+    val list = findViewById(android.R.id.list).asInstanceOf[ListView]
+    list.setAdapter(adapter)
+    list.setOnItemClickListener(this)
+    list.setEmptyView(findViewById(android.R.id.empty))
+
+    val filter = new IntentFilter()
+    filter.addAction(ChatService.ActionConnectionsChanged)
+    filter.addAction(Database.ActionContactsUpdated)
+    LocalBroadcastManager.getInstance(this)
+      .registerReceiver(onContactsUpdatedReceiver, filter)
+  }
+
+  override def onDestroy(): Unit = {
+    super.onDestroy()
+    LocalBroadcastManager.getInstance(this).unregisterReceiver(onContactsUpdatedReceiver)
+  }
+
+  /**
+   * Initiates adding the device as contact if it hasn't been added yet.
+   */
+  override def onItemClick(parent: AdapterView[_], view: View, position: Int, id: Long): Unit = {
+    val contact = adapter.getItem(position)
+    new Builder(this)
+      .setMessage(getString(R.string.dialog_add_contact, contact.name))
+      .setPositiveButton(android.R.string.yes, new OnClickListener {
+        override def onClick(dialog: DialogInterface, which: Int): Unit = {
+          database.addContact(contact)
+          Toast.makeText(AddContactsActivity.this, R.string.toast_contact_added, Toast.LENGTH_SHORT)
+            .show()
+        }
+      })
+      .setNegativeButton(android.R.string.no, null)
+      .show()
+  }
+
+  override def onOptionsItemSelected(item: MenuItem): Boolean = item.getItemId match {
+    case android.R.id.home =>
+      NavUtils.navigateUpFromSameTask(this)
+      true
+    case _ =>
+      super.onOptionsItemSelected(item);
+  }
+
+  /**
+   * Fetches connections and displays them (excluding contacts).
+   */
+  private val onContactsUpdatedReceiver = new BroadcastReceiver() {
+    override def onReceive(context: Context, intent: Intent): Unit = {
+      runOnUiThread(new Runnable {
+        override def run(): Unit  = {
+          adapter.clear()
+          (service.connections().map(a => service.getUser(a)) -- database.getContacts)
+            .foreach(adapter.add)
+        }
+      })
+    }
+  }
+
+}
--- a/android/src/main/scala/com/nutomic/ensichat/activities/EnsichatActivity.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/activities/EnsichatActivity.scala
@ -3,7 +3,7 @@ package com.nutomic.ensichat.activities
 import android.content.{ComponentName, Context, Intent, ServiceConnection}
 import android.os.{Bundle, IBinder}
 import android.support.v7.app.AppCompatActivity
-import com.nutomic.ensichat.service.ChatService
+import com.nutomic.ensichat.protocol.{ChatService, ChatServiceBinder}

 /**
 * Connects to [[ChatService]] and provides access to it.
@ -37,7 +37,7 @@ class EnsichatActivity extends AppCompatActivity with ServiceConnection {
   * Clears the list containing them.
   */
  override def onServiceConnected(componentName: ComponentName, iBinder: IBinder): Unit = {
-    val binder = iBinder.asInstanceOf[ChatService.Binder]
+    val binder = iBinder.asInstanceOf[ChatServiceBinder]
    chatService = Option(binder.service)
    listeners.foreach(_())
    listeners = Set.empty
@ -58,10 +58,8 @@ class EnsichatActivity extends AppCompatActivity with ServiceConnection {
  /**
   * Returns the [[ChatService]].
   *
-   * Will only be set after [[runOnServiceConnected]].
+   * Should only be called after [[runOnServiceConnected]] callback was called.
   */
-  def service = chatService.map(_.getConnectionHandler)
-
-  def database = chatService.map(_.database)
+  def service = chatService.get

 }
--- a/android/src/main/scala/com/nutomic/ensichat/activities/FirstStartActivity.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/activities/FirstStartActivity.scala
@ -1,22 +1,17 @@
 package com.nutomic.ensichat.activities

-import android.Manifest
 import android.bluetooth.BluetoothAdapter
-import android.content.pm.PackageManager
 import android.content.{Context, Intent}
 import android.os.Bundle
 import android.preference.PreferenceManager
-import android.support.v4.app.ActivityCompat
-import android.support.v4.content.ContextCompat
 import android.support.v7.app.AppCompatActivity
 import android.view.View.OnClickListener
 import android.view.inputmethod.{EditorInfo, InputMethodManager}
 import android.view.{KeyEvent, View}
 import android.widget.TextView.OnEditorActionListener
-import android.widget.{Button, EditText, TextView, Toast}
+import android.widget.{Button, EditText, TextView}
 import com.nutomic.ensichat.R
-import com.nutomic.ensichat.core.interfaces.SettingsInterface
-import com.nutomic.ensichat.core.interfaces.SettingsInterface._
+import com.nutomic.ensichat.fragments.SettingsFragment

 /**
 * Shown on first start, lets the user enter their name.
@ -24,7 +19,6 @@ import com.nutomic.ensichat.core.interfaces.SettingsInterface._
 class FirstStartActivity extends AppCompatActivity with OnEditorActionListener with OnClickListener {

  private val KeyIsFirstStart = "first_start"
-  private val RequestLocationPermission = 127

  private lazy val preferences = PreferenceManager.getDefaultSharedPreferences(this)
  private lazy val imm = getSystemService(Context.INPUT_METHOD_SERVICE)
@ -36,24 +30,19 @@ class FirstStartActivity extends AppCompatActivity with OnEditorActionListener w
  override def onCreate(savedInstanceState: Bundle): Unit = {
    super.onCreate(savedInstanceState)

+    if (!preferences.getBoolean(KeyIsFirstStart, true)) {
+      startMainActivity()
+      return
+    }
+
    setContentView(R.layout.activity_first_start)
    setTitle(R.string.welcome)

-    val name = Option(BluetoothAdapter.getDefaultAdapter).map(_.getName.trim).getOrElse("")
-    username.setText(name)
+    username.setText(BluetoothAdapter.getDefaultAdapter.getName.trim)
    username.setOnEditorActionListener(this)
    done.setOnClickListener(this)

-    val permission = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
-    if (preferences.getBoolean(KeyIsFirstStart, true)) {
-      imm.showSoftInput(username, InputMethodManager.SHOW_IMPLICIT)
-    }
-    else if (permission != PackageManager.PERMISSION_GRANTED) {
-      requestLocationPermission()
-    }
-    else {
-      startMainActivity()
-    }
+    imm.showSoftInput(username, InputMethodManager.SHOW_IMPLICIT)
  }

  /**
@ -71,7 +60,7 @@ class FirstStartActivity extends AppCompatActivity with OnEditorActionListener w
  override def onClick(v: View): Unit = save()

  /**
-   * Saves username and default settings values, then calls [[startMainActivity]].
+   * Saves values and calls [[startMainActivity]].
   */
  private def save(): Unit = {
    imm.hideSoftInputFromWindow(username.getWindowToken, 0)
@ -79,27 +68,11 @@ class FirstStartActivity extends AppCompatActivity with OnEditorActionListener w
    preferences
      .edit()
      .putBoolean(KeyIsFirstStart, false)
-      .putString(KeyUserName,               username.getText.toString.trim)
-      .putString(KeyUserStatus,             SettingsInterface.DefaultUserStatus)
-      .putBoolean(KeyNotificationSoundsOn,  DefaultNotificationSoundsOn)
-      .putString(KeyScanInterval,           DefaultScanInterval.toString)
-      .putString(KeyAddresses,              DefaultAddresses)
+      .putString(SettingsFragment.KeyUserName, username.getText.toString.trim)
+      .putString(SettingsFragment.KeyUserStatus, getString(R.string.default_user_status))
      .apply()

-    requestLocationPermission()
-  }
-
-  private def requestLocationPermission(): Unit =
-    ActivityCompat.requestPermissions(this, Array(Manifest.permission.ACCESS_COARSE_LOCATION), RequestLocationPermission)
-
-  override def onRequestPermissionsResult(requestCode: Int,
-                                          permissions: Array[String], grantResults: Array[Int]): Unit = requestCode match {
-    case RequestLocationPermission =>
-      if (grantResults.length > 0 && grantResults(0) == PackageManager.PERMISSION_GRANTED) {
-        startMainActivity()
-      } else {
-        Toast.makeText(this, R.string.toast_location_required, Toast.LENGTH_SHORT).show()
-      }
+    startMainActivity()
  }

  def startMainActivity(): Unit = {
--- a/android/src/main/scala/com/nutomic/ensichat/activities/MainActivity.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/activities/MainActivity.scala
@ -4,12 +4,11 @@ import android.app.Activity
 import android.bluetooth.BluetoothAdapter
 import android.content._
 import android.os.Bundle
-import android.preference.PreferenceManager
 import android.view.MenuItem
 import android.widget.Toast
 import com.nutomic.ensichat.R
-import com.nutomic.ensichat.core.routing.Address
 import com.nutomic.ensichat.fragments.{ChatFragment, ContactsFragment}
+import com.nutomic.ensichat.protocol.Address

 object MainActivity {

@ -25,8 +24,6 @@ object MainActivity {

  val ExtraAddress = "address"

-  val PrefWasBluetoothEnabled = "was_bluetooth_enabled"
-
 }

 /**
@ -47,14 +44,7 @@ class MainActivity extends EnsichatActivity {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

-    if (getIntent.getAction == MainActivity.ActionRequestBluetooth &&
-        Option(BluetoothAdapter.getDefaultAdapter).isDefined) {
-      val btAdapter = BluetoothAdapter.getDefaultAdapter
-      PreferenceManager.getDefaultSharedPreferences(this)
-        .edit()
-        .putBoolean(MainActivity.PrefWasBluetoothEnabled, btAdapter.isEnabled)
-        .apply()
-
+    if (getIntent.getAction == MainActivity.ActionRequestBluetooth) {
      val intent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE)
      intent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 0)
      startActivityForResult(intent, RequestSetDiscoverable)
@ -99,7 +89,8 @@ class MainActivity extends EnsichatActivity {
    requestCode match {
      case RequestSetDiscoverable =>
        if (resultCode == Activity.RESULT_CANCELED) {
-          Toast.makeText(this, R.string.toast_bluetooth_denied, Toast.LENGTH_LONG).show()
+          Toast.makeText(this, R.string.bluetooth_required, Toast.LENGTH_LONG).show()
+          finish()
        }
    }

@ -113,7 +104,7 @@ class MainActivity extends EnsichatActivity {
      .detach(contactsFragment)
      .add(android.R.id.content, new ChatFragment(address))
      .commit()
-    Option(getSupportActionBar).foreach(_.setDisplayHomeAsUpEnabled(true))
+    getSupportActionBar.setDisplayHomeAsUpEnabled(true)
  }

  /**
@ -135,8 +126,7 @@ class MainActivity extends EnsichatActivity {

  override def onOptionsItemSelected(item: MenuItem): Boolean = item.getItemId match {
    case android.R.id.home =>
-      if (currentChat.isDefined)
-        onBackPressed()
+      onBackPressed()
      true;
    case _ =>
      super.onOptionsItemSelected(item);
--- a/android/src/main/scala/com/nutomic/ensichat/activities/SettingsActivity.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/activities/SettingsActivity.scala
--- a/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala
@ -7,14 +7,12 @@ 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.core.interfaces.{SettingsInterface, TransmissionInterface}
-import com.nutomic.ensichat.core.messages.Message
-import com.nutomic.ensichat.core.messages.body.ConnectionInfo
-import com.nutomic.ensichat.core.routing.Address
-import com.nutomic.ensichat.core.ConnectionHandler
-import com.nutomic.ensichat.service.ChatService
-import org.joda.time.{DateTime, Duration}
+import com.nutomic.ensichat.fragments.SettingsFragment
+import com.nutomic.ensichat.protocol.ChatService.InterfaceHandler
+import com.nutomic.ensichat.protocol._
+import com.nutomic.ensichat.protocol.body.ConnectionInfo

 import scala.collection.immutable.HashMap

@ -31,25 +29,27 @@ object BluetoothInterface {
 * Handles all Bluetooth connectivity.
 */
 class BluetoothInterface(context: Context, mainHandler: Handler,
-                         connectionHandler: ConnectionHandler) extends TransmissionInterface {
+                         onMessageReceived: Message => Unit, callConnectionListeners: () => Unit,
+                         onConnectionOpened: (Message) => Boolean)
+  extends InterfaceHandler {

  private val Tag = "BluetoothInterface"

  private lazy val btAdapter = BluetoothAdapter.getDefaultAdapter

-  private lazy val crypto = ChatService.newCrypto(context)
+  private lazy val crypto = new Crypto(context)

  private var devices = new HashMap[Device.ID, Device]()

-  private var connections = new HashMap[Device.ID, BluetoothTransferThread]()
+  private var connections = new HashMap[Device.ID, TransferThread]()

-  private var listenThread: Option[BluetoothListenThread] = None
+  private var listenThread: Option[ListenThread] = None

  private var cancelDiscovery = false

  private var discovered = Set[Device]()

-  private var addressDeviceMap = new HashMap[Address, Device.ID]()
+  private val addressDeviceMap = HashBiMap.create[Address, Device.ID]()

  /**
   * Initializes and starts discovery and listening.
@ -71,7 +71,7 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
   * Stops discovery and listening.
   */
  override def destroy(): Unit = {
-    listenThread.foreach(_.cancel())
+    listenThread.get.cancel()
    listenThread = None
    cancelDiscovery = true
    try {
@ -89,7 +89,7 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
   * Starts discovery and listening.
   */
  private def startBluetoothConnections(): Unit = {
-    listenThread = Some(new BluetoothListenThread(context.getString(R.string.app_name), btAdapter, connectionOpened))
+    listenThread = Some(new ListenThread(context.getString(R.string.app_name), btAdapter, connectionOpened))
    listenThread.get.start()
    cancelDiscovery = false
    discover()
@ -108,8 +108,8 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
    }

    val pm = PreferenceManager.getDefaultSharedPreferences(context)
-    val scanInterval =
-      pm.getString(SettingsInterface.KeyScanInterval, SettingsInterface.DefaultScanInterval.toString).toInt * 1000
+    val scanInterval = pm.getString(SettingsFragment.KeyScanInterval,
+      context.getResources.getString(R.string.default_scan_interval)).toInt * 1000
    mainHandler.postDelayed(new Runnable {
      override def run(): Unit = discover()
    }, scanInterval)
@ -131,7 +131,7 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
    override def onReceive(context: Context, intent: Intent): Unit = {
      discovered.filterNot(d => connections.keySet.contains(d.id))
        .foreach { d =>
-          new BluetoothConnectThread(d, connectionOpened).start()
+          new ConnectThread(d, connectionOpened).start()
          devices += (d.id -> d)
        }
      discovered = Set[Device]()
@ -165,20 +165,18 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
  def connectionOpened(device: Device, socket: BluetoothSocket): Unit = {
    devices += (device.id -> device)
    connections += (device.id ->
-      new BluetoothTransferThread(context, device, socket, this, crypto, onReceiveMessage))
+      new TransferThread(context, device, socket, this, crypto, onReceiveMessage))
    connections(device.id).start()
  }

  /**
   * Removes device from active connections.
   */
-  def onConnectionClosed(connectionOpened: DateTime, deviceId: Device.ID): Unit = {
-    val address = getAddressForDevice(deviceId)
-    devices -= deviceId
-    connections -= deviceId
-    addressDeviceMap = addressDeviceMap.filterNot(_._2 == deviceId)
-    val connectionDuration = new Duration(connectionOpened, DateTime.now)
-    connectionHandler.onConnectionClosed(address, connectionDuration)
+  def onConnectionClosed(device: Device, socket: BluetoothSocket): Unit = {
+    devices -= device.id
+    connections -= device.id
+    callConnectionListeners()
+    addressDeviceMap.inverse().remove(device.id)
  }

  /**
@ -193,31 +191,23 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
    case info: ConnectionInfo =>
      val address = crypto.calculateAddress(info.key)
      // Service.onConnectionOpened sends message, so mapping already needs to be in place.
-      addressDeviceMap += (address -> device)
-      if (!connectionHandler.onConnectionOpened(msg))
-        addressDeviceMap -= address
+      addressDeviceMap.put(address, device)
+      if (!onConnectionOpened(msg))
+        addressDeviceMap.remove(address)
    case _ =>
-      connectionHandler.onMessageReceived(msg, getAddressForDevice(device))
+      onMessageReceived(msg)
  }

-  private def getAddressForDevice(device: Device.ID) =
-    addressDeviceMap.find(_._2 == device).get._1
-
  /**
   * Sends the message to nextHop.
   */
-  override def send(nextHop: Address, msg: Message): Unit = {
-    addressDeviceMap
-      .find(_._1 == nextHop || Address.Broadcast == nextHop)
-      .map(i => connections.get(i._2))
-      .getOrElse(None)
-      .foreach(_.send(msg))
-  }
+  override def send(nextHop: Address, msg: Message): Unit =
+    connections.get(addressDeviceMap.get(nextHop)).foreach(_.send(msg))

  /**
   * Returns all active Bluetooth connections.
   */
-  override def getConnections: Set[Address] =
-    connections.map( c => getAddressForDevice(c._1)).toSet
+  def getConnections: Set[Address] =
+    connections.map(x => addressDeviceMap.inverse().get(x._1)).toSet

 }
--- a/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothConnectThread.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothConnectThread.scala
@ -8,30 +8,22 @@ import android.util.Log
 /**
 * Attempts to connect to another device and calls [[onConnected]] on success.
 */
-class BluetoothConnectThread(device: Device, onConnected: (Device, BluetoothSocket) => Unit) extends Thread {
+class ConnectThread(device: Device, onConnected: (Device, BluetoothSocket) => Unit) extends Thread {

  private val Tag = "ConnectThread"

-  private val socket = try {
-    Option(device.btDevice.get.createInsecureRfcommSocketToServiceRecord(BluetoothInterface.AppUuid))
-  } catch {
-    case e: IOException =>
-      Log.w(Tag, "Failed to open Bluetooth connection", e)
-      None
-  }
+  private val socket =
+      device.btDevice.get.createInsecureRfcommSocketToServiceRecord(BluetoothInterface.AppUuid)

  override def run(): Unit = {
-    if (socket.isEmpty)
-      return
-
    Log.i(Tag, "Connecting to " + device.toString)
    try {
-      socket.get.connect()
+      socket.connect()
    } catch {
      case e: IOException =>
        Log.v(Tag, "Failed to connect to " + device.toString, e)
        try {
-          socket.get.close()
+          socket.close()
        } catch {
          case e2: IOException =>
            Log.e(Tag, "Failed to close socket", e2)
@ -40,7 +32,7 @@ class BluetoothConnectThread(device: Device, onConnected: (Device, BluetoothSock
    }

    Log.i(Tag, "Successfully connected to device " + device.name)
-    onConnected(new Device(device.btDevice.get, true), socket.get)
+    onConnected(new Device(device.btDevice.get, true), socket)
  }

 }
--- a/Show more
+++ b/Show more