[BIG COMMIT] Made a username system and slightly fixed the signature system. Refactor.

2024-11-25 00:22:17 +00:00 · 2019-04-16 14:52:41 +04:00 · 2019-04-16 14:52:41 +04:00 · 99409e1a13
commit 99409e1a13
parent 1eb1f0c0bc
44 changed files with 565 additions and 381 deletions
--- a/app/build.gradle
+++ b/app/build.gradle
@ -29,6 +29,7 @@ android {
        exclude 'META-INF/io.netty.versions.properties'
        exclude 'LICENSE-EPL-1.0.txt'
        exclude 'LICENSE-EDL-1.0.txt'
+        exclude 'META-INF/atomicfu.kotlin_module'
    }

    compileOptions {
@ -40,20 +41,19 @@ android {
 dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'androidx.appcompat:appcompat:1.1.0-alpha02'
-    implementation 'androidx.constraintlayout:constraintlayout:2.0.0-alpha3'
    implementation "androidx.room:room-runtime:2.1.0-alpha04"
    annotationProcessor "androidx.room:room-compiler:2.1.0-alpha04"
    implementation 'org.slf4j:slf4j-log4j12:1.7.26'
-    implementation group: 'com.h2database', name: 'h2-mvstore', version: '1.4.197'
    implementation 'net.tomp2p:tomp2p-all:5.0-Beta8'
    implementation 'com.google.android.material:material:1.1.0-alpha04'
    implementation 'androidx.preference:preference:1.1.0-alpha03'
    implementation 'com.google.code.gson:gson:2.8.5'
-    implementation group: 'org.springframework.security', name: 'spring-security-crypto', version: '3.1.0.RELEASE'
    implementation 'de.hdodenhof:circleimageview:3.0.0'
-    implementation group: 'org.objenesis', name: 'objenesis', version: '2.6'
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
    implementation 'com.android.support:multidex:1.0.3'
+    implementation "org.jetbrains.anko:anko:0.10.8"
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.0'
+    implementation 'com.esotericsoftware:kryo:5.0.0-RC1'
 }
 repositories {
    mavenCentral()
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@ -3,14 +3,16 @@
    xmlns:tools="http://schemas.android.com/tools"
    package="io.github.chronosx88.influence">

+    <uses-permission android:name="android.permission.INTERNET" />
+
    <application
+        android:name=".helpers.AppHelper"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
-        android:theme="@style/AppTheme"
-        android:name=".helpers.AppHelper">
+        android:theme="@style/AppTheme">
        <activity android:name=".views.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
@ -20,7 +22,7 @@
        </activity>
        <activity
            android:name=".views.ChatActivity"
-            android:theme="@style/NoWindowActionBar"/>
+            android:theme="@style/NoWindowActionBar" />
    </application>
-    <uses-permission android:name="android.permission.INTERNET"/>
+
 </manifest>
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/CoreContracts.kt
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/CoreContracts.kt
@ -0,0 +1,91 @@
+package io.github.chronosx88.influence.contracts
+
+import android.content.Intent
+import android.view.MenuItem
+
+import io.github.chronosx88.influence.helpers.ChatListAdapter
+import io.github.chronosx88.influence.models.roomEntities.ChatEntity
+import io.github.chronosx88.influence.models.roomEntities.MessageEntity
+
+interface CoreContracts {
+
+    // -----ChatList-----
+
+    interface IChatListLogicContract {
+        fun loadAllChats(): List<ChatEntity>
+    }
+
+    interface IChatListPresenterContract {
+        fun updateChatList()
+        fun openChat(chatID: String)
+        fun onContextItemSelected(item: MenuItem)
+    }
+
+    interface IChatListViewContract {
+        fun setRecycleAdapter(adapter: ChatListAdapter)
+        fun startActivity(intent: Intent)
+        fun updateChatList(adapter: ChatListAdapter, chats: List<ChatEntity>)
+    }
+
+    // -----StartChat-----
+
+    interface IStartChatLogicContract {
+        fun sendStartChatMessage(peerID: String)
+    }
+
+    interface IStartChatPresenterContract {
+        fun startChatWithPeer(peerID: String)
+    }
+
+    interface IStartChatViewContract {
+        fun showMessage(message: String)
+        fun showProgressDialog(enabled: Boolean)
+    }
+
+    // -----MainActivity-----
+
+    interface IMainLogicContract {
+        fun initPeer()
+        fun shutdownPeer()
+    }
+
+    interface IMainPresenterContract {
+        fun initPeer()
+        fun onDestroy()
+    }
+
+    interface IMainViewContract//
+
+    // -----ChatActivity-----
+
+    interface IChatLogicContract {
+        fun sendMessage(message: MessageEntity)
+        fun stopTrackingForNewMsgs()
+    }
+
+    interface IChatPresenterContract {
+        fun sendMessage(text: String)
+        fun updateAdapter()
+        fun onDestroy()
+    }
+
+    interface IChatViewContract {
+        fun updateMessageList(message: MessageEntity)
+        fun updateMessageList(messages: List<MessageEntity>)
+    }
+
+    // -----SettingsFragment-----
+
+    interface ISettingsLogic {
+        fun checkUsernameExists(username: String) : Boolean
+    }
+
+    interface ISettingsPresenter {
+        fun updateUsername(username: String)
+    }
+
+    interface ISettingsView {
+        fun loadingScreen(state: Boolean)
+        fun showMessage(message: String)
+    }
+}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/chatactivity/IChatLogicContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/chatactivity/IChatLogicContract.java
@ -1,8 +0,0 @@
-package io.github.chronosx88.influence.contracts.chatactivity;
-
-import io.github.chronosx88.influence.models.roomEntities.MessageEntity;
-
-public interface IChatLogicContract {
-    void sendMessage(MessageEntity message);
-    void stopTrackingForNewMsgs();
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/chatactivity/IChatPresenterContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/chatactivity/IChatPresenterContract.java
@ -1,7 +0,0 @@
-package io.github.chronosx88.influence.contracts.chatactivity;
-
-public interface IChatPresenterContract {
-    void sendMessage(String text);
-    void updateAdapter();
-    void onDestroy();
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/chatactivity/IChatViewContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/chatactivity/IChatViewContract.java
@ -1,10 +0,0 @@
-package io.github.chronosx88.influence.contracts.chatactivity;
-
-import java.util.List;
-
-import io.github.chronosx88.influence.models.roomEntities.MessageEntity;
-
-public interface IChatViewContract {
-    void updateMessageList(MessageEntity message);
-    void updateMessageList(List<MessageEntity> messages);
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/chatlist/IChatListLogicContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/chatlist/IChatListLogicContract.java
@ -1,9 +0,0 @@
-package io.github.chronosx88.influence.contracts.chatlist;
-
-import java.util.List;
-
-import io.github.chronosx88.influence.models.roomEntities.ChatEntity;
-
-public interface IChatListLogicContract {
-    List<ChatEntity> loadAllChats();
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/chatlist/IChatListPresenterContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/chatlist/IChatListPresenterContract.java
@ -1,9 +0,0 @@
-package io.github.chronosx88.influence.contracts.chatlist;
-
-import android.view.MenuItem;
-
-public interface IChatListPresenterContract {
-    void updateChatList();
-    void openChat(String chatID);
-    void onContextItemSelected(MenuItem item);
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/chatlist/IChatListViewContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/chatlist/IChatListViewContract.java
@ -1,14 +0,0 @@
-package io.github.chronosx88.influence.contracts.chatlist;
-
-import android.content.Intent;
-
-import java.util.List;
-
-import io.github.chronosx88.influence.helpers.ChatListAdapter;
-import io.github.chronosx88.influence.models.roomEntities.ChatEntity;
-
-public interface IChatListViewContract {
-    void setRecycleAdapter(ChatListAdapter adapter);
-    void startActivity(Intent intent);
-    void updateChatList(ChatListAdapter adapter, List<ChatEntity> chats);
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/mainactivity/IMainLogicContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/mainactivity/IMainLogicContract.java
@ -1,6 +0,0 @@
-package io.github.chronosx88.influence.contracts.mainactivity;
-
-public interface IMainLogicContract {
-    void initPeer();
-    void shutdownPeer();
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/mainactivity/IMainPresenterContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/mainactivity/IMainPresenterContract.java
@ -1,6 +0,0 @@
-package io.github.chronosx88.influence.contracts.mainactivity;
-
-public interface IMainPresenterContract {
-    void initPeer();
-    void onDestroy();
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/mainactivity/IMainViewContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/mainactivity/IMainViewContract.java
@ -1,5 +0,0 @@
-package io.github.chronosx88.influence.contracts.mainactivity;
-
-public interface IMainViewContract {
-    //
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/startchat/IStartChatLogicContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/startchat/IStartChatLogicContract.java
@ -1,5 +0,0 @@
-package io.github.chronosx88.influence.contracts.startchat;
-
-public interface IStartChatLogicContract {
-    void sendStartChatMessage(String peerID);
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/startchat/IStartChatPresenterContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/startchat/IStartChatPresenterContract.java
@ -1,5 +0,0 @@
-package io.github.chronosx88.influence.contracts.startchat;
-
-public interface IStartChatPresenterContract {
-    void startChatWithPeer(String peerID);
-}
--- a/app/src/main/java/io/github/chronosx88/influence/contracts/startchat/IStartChatViewContract.java
+++ b/app/src/main/java/io/github/chronosx88/influence/contracts/startchat/IStartChatViewContract.java
@ -1,6 +0,0 @@
-package io.github.chronosx88.influence.contracts.startchat;
-
-public interface IStartChatViewContract {
-    void showMessage(String message);
-    void showProgressDialog(boolean enabled);
-}
--- a/app/src/main/java/io/github/chronosx88/influence/helpers/AppHelper.java
+++ b/app/src/main/java/io/github/chronosx88/influence/helpers/AppHelper.java
@ -2,6 +2,7 @@ package io.github.chronosx88.influence.helpers;

 import android.app.Application;
 import android.content.Context;
+import android.content.SharedPreferences;

 import net.tomp2p.dht.PeerDHT;

@ -10,7 +11,7 @@ import androidx.room.Room;
 import io.github.chronosx88.influence.observable.MainObservable;

 /**
- * Extended Application class which designed for getting various objects from anywhere in the application.
+ * Extended Application class which designed for centralized getting various objects from anywhere in the application.
 */

 public class AppHelper extends MultiDexApplication {
@ -20,6 +21,8 @@ public class AppHelper extends MultiDexApplication {
    private static PeerDHT peerDHT;
    private static RoomHelper chatDB;
    private static NetworkHandler networkHandler;
+    private static String username = "";
+    private static SharedPreferences preferences;

    @Override
    public void onCreate() {
@ -29,10 +32,13 @@ public class AppHelper extends MultiDexApplication {
        chatDB = Room.databaseBuilder(getApplicationContext(), RoomHelper.class, "chatDB")
                    .allowMainThreadQueries()
                    .build();
+        preferences = getApplicationContext().getSharedPreferences("io.github.chronosx88.influence_preferences", MODE_PRIVATE);
    }

    public static void storePeerID(String peerID1) { peerID = peerID1; }

+    public static void updateUsername(String username1) { username = username1; }
+
    public static void storePeerDHT(PeerDHT peerDHT1) { peerDHT = peerDHT1; }

    public static Context getContext() {
@ -43,9 +49,15 @@ public class AppHelper extends MultiDexApplication {

    public static String getPeerID() { return peerID; }

+    public static String getUsername() { return username; }
+
    public static PeerDHT getPeerDHT() { return peerDHT; }

    public static RoomHelper getChatDB() { return chatDB; }

    public static void initNetworkHandler() { networkHandler = new NetworkHandler(); }
+
+    public static SharedPreferences getPreferences() {
+        return preferences;
+    }
 }
--- a/app/src/main/java/io/github/chronosx88/influence/helpers/DataSerializerEx.kt
+++ b/app/src/main/java/io/github/chronosx88/influence/helpers/DataSerializerEx.kt
@ -7,6 +7,7 @@ import io.netty.buffer.Unpooled
 import net.tomp2p.connection.SignatureFactory
 import net.tomp2p.storage.AlternativeCompositeByteBuf
 import net.tomp2p.storage.Data
+import org.mapdb.DataInput2
 import java.io.*
 import java.nio.ByteBuffer
 import java.security.InvalidKeyException
@ -27,7 +28,7 @@ class DataSerializerEx(private val signatureFactory: SignatureFactory) : EntryBi
            data = Data.decodeHeader(buf, signatureFactory)
        }
        val len = data.length()
-        val me = ByteArray(len)
+        var me = ByteArray(len)
        try {
            inputStream.read(me)
        } catch (e: IOException) {
@ -39,6 +40,14 @@ class DataSerializerEx(private val signatureFactory: SignatureFactory) : EntryBi
        if (!retVal) {
            Log.e(LOG_TAG, "# ERROR: Data could not be deserialized!")
        }
+        val dataInput = DataInputStream(inputStream)
+        me = ByteArray(signatureFactory.signatureSize())
+        dataInput.readFully(me)
+        buf = Unpooled.wrappedBuffer(me)
+        retVal = data.decodeDone(buf, signatureFactory);
+        if(!retVal) {
+            throw IOException("signature could not be read")
+        }
        return data
    }

--- a/app/src/main/java/io/github/chronosx88/influence/helpers/KeyPairManager.java
+++ b/app/src/main/java/io/github/chronosx88/influence/helpers/KeyPairManager.java
@ -25,7 +25,6 @@ public class KeyPairManager {
    }

    public KeyPair getKeyPair(String keyPairName) {
-        KeyPair keyPair = null;
        keyPairName = keyPairName + ".kp";
        File keyPairFile = new File(keyPairDir, keyPairName);
        if (!keyPairFile.exists()) {
@ -52,7 +51,9 @@ public class KeyPairManager {
        KeyPair keyPair = null;
        try {
            keyPairFile.createNewFile();
-            keyPair = KeyPairGenerator.getInstance("RSA").generateKeyPair();
+            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
+            keyPairGenerator.initialize(1024);
+            keyPair = keyPairGenerator.generateKeyPair();
            FileOutputStream outputStream = new FileOutputStream(keyPairFile);
            outputStream.write(serializer.serialize(keyPair));
            outputStream.close();
--- a/app/src/main/java/io/github/chronosx88/influence/helpers/NetworkHandler.java
+++ b/app/src/main/java/io/github/chronosx88/influence/helpers/NetworkHandler.java
@ -58,7 +58,7 @@ public class NetworkHandler implements INetworkObserver {

                LocalDBWrapper.createChatEntry(
                        newChatRequestMessage.getChatID(),
-                        newChatRequestMessage.getSenderID(),
+                        newChatRequestMessage.getUsername(),
                        newChatRequestMessage.getChatID() + "_metadata",
                        newChatRequestMessage.getChatID() + "_members",
                        newChatRequestMessage.getChunkID()
@ -67,7 +67,7 @@ public class NetworkHandler implements INetworkObserver {
                P2PUtils.remove(AppHelper.getPeerID() + "_pendingChats", newChatRequestMessage.getChatID());
                String messageID = UUID.randomUUID().toString();
                try {
-                    P2PUtils.put(newChatRequestMessage.getChatID() + "_messages", messageID, new Data(gson.toJson(new JoinChatMessage(AppHelper.getPeerID(), AppHelper.getPeerID(), newChatRequestMessage.getChatID(), System.currentTimeMillis()))).protectEntry(keyPairManager.openMainKeyPair()));
+                    P2PUtils.put(newChatRequestMessage.getChatID() + "_messages", messageID, new Data(gson.toJson(new JoinChatMessage(AppHelper.getPeerID(), AppHelper.getUsername() == null ? AppHelper.getPeerID() : AppHelper.getUsername(), newChatRequestMessage.getChatID(), System.currentTimeMillis()))).protectEntry(keyPairManager.openMainKeyPair()));
                } catch (IOException e) {
                    e.printStackTrace();
                }
@ -75,6 +75,4 @@ public class NetworkHandler implements INetworkObserver {
            }
        }
    }
-
-
 }
--- a/app/src/main/java/io/github/chronosx88/influence/helpers/P2PUtils.java
+++ b/app/src/main/java/io/github/chronosx88/influence/helpers/P2PUtils.java
@ -13,34 +13,14 @@ import net.tomp2p.peers.Number640;
 import net.tomp2p.peers.PeerAddress;
 import net.tomp2p.storage.Data;

+import java.security.KeyPair;
 import java.util.Map;

 public class P2PUtils {
    private static Gson gson = new Gson();
    private static PeerDHT peerDHT = AppHelper.getPeerDHT();

-    public static boolean ping(PeerAddress recipientPeerAddress) {
-        // For connection opening
-        for (int i = 0; i < 5; i++) {
-            peerDHT
-                    .peer()
-                    .ping()
-                    .peerAddress(recipientPeerAddress)
-                    .start()
-                    .awaitUninterruptibly();
-        }
-
-        FuturePing ping = peerDHT
-                .peer()
-                .ping()
-                .peerAddress(recipientPeerAddress)
-                .start()
-                .awaitUninterruptibly();
-        return ping.isSuccess();
-    }
-
    public static boolean put(String locationKey, String contentKey, Data data) {
-        data.signed(false);
        FuturePut futurePut = peerDHT
                .put(Number160.createHash(locationKey))
                .data(contentKey == null ? Number160.ZERO : Number160.createHash(contentKey), data)
@ -49,6 +29,16 @@ public class P2PUtils {
        return futurePut.isSuccess();
    }

+    public static boolean put(String locationKey, String contentKey, Data data, KeyPair keyPair) {
+        FuturePut futurePut = peerDHT
+                .put(Number160.createHash(locationKey))
+                .data(contentKey == null ? Number160.ZERO : Number160.createHash(contentKey), data)
+                .keyPair(keyPair)
+                .start()
+                .awaitUninterruptibly();
+        return futurePut.isSuccess();
+    }
+
    public static Map<Number640, Data> get(String locationKey) {
        FutureGet futureGet = peerDHT
                .get(Number160.createHash(locationKey))
@ -61,16 +51,6 @@ public class P2PUtils {
        return null;
    }

-    public static boolean send(PeerAddress address, String data) {
-        FutureDirect futureDirect = peerDHT
-                .peer()
-                .sendDirect(address)
-                .object(data)
-                .start()
-                .awaitUninterruptibly();
-        return futureDirect.isSuccess();
-    }
-
    public static boolean remove(String locationKey, String contentKey) {
        FutureRemove futureRemove = peerDHT
                .remove(Number160.createHash(locationKey))
@ -79,4 +59,14 @@ public class P2PUtils {
                .awaitUninterruptibly();
        return futureRemove.isRemoved();
    }
+
+    public static boolean remove(String locationKey, String contentKey, KeyPair keyPair) {
+        FutureRemove futureRemove = peerDHT
+                .remove(Number160.createHash(locationKey))
+                .keyPair(keyPair)
+                .contentKey(contentKey == null ? null : Number160.createHash(contentKey))
+                .start()
+                .awaitUninterruptibly();
+        return futureRemove.isRemoved();
+    }
 }
--- a/app/src/main/java/io/github/chronosx88/influence/helpers/StorageBerkeleyDB.kt
+++ b/app/src/main/java/io/github/chronosx88/influence/helpers/StorageBerkeleyDB.kt
@ -72,7 +72,7 @@ class StorageBerkeleyDB(peerId: Number160, path : File, signatureFactory: Signat

        storageCheckIntervalMillis = 60 * 1000

-        dataMap = StoredSortedMap(dataMapDB, Serializer<Number640>(), DataSerializerEx(signatureFactory), true)
+        dataMap = StoredSortedMap(dataMapDB, Serializer<Number640>(), DataSerializer(signatureFactory), true)
        timeoutMap = StoredSortedMap(timeoutMapDB, Serializer<Number640>(), Serializer<Long>(), true)
        timeoutMapRev = StoredSortedMap(timeoutMapRevDB, Serializer<Long>(), Serializer<Set<Number640>>(), true)
        protectedDomainMap = StoredSortedMap(protectedDomainMapDB, Serializer<Number320>(), Serializer<PublicKey>(), true)
@ -89,8 +89,8 @@ class StorageBerkeleyDB(peerId: Number160, path : File, signatureFactory: Signat
        return dataMap.subMap(from, true, to, true).size
    }

-    override fun findContentForResponsiblePeerID(peerID: Number160?): MutableSet<Number160> {
-        return responsibilityMapRev[peerID] as MutableSet<Number160>
+    override fun findContentForResponsiblePeerID(peerID: Number160?): MutableSet<Number160>? {
+        return responsibilityMapRev[peerID] as MutableSet<Number160>?
    }

    override fun findPeerIDsForResponsibleContent(locationKey: Number160?): Number160? {
--- a/app/src/main/java/io/github/chronosx88/influence/helpers/actions/UIActions.java
+++ b/app/src/main/java/io/github/chronosx88/influence/helpers/actions/UIActions.java
@ -12,4 +12,6 @@ public class UIActions {
    public static final int SUCCESSFUL_CREATE_CHAT = 0x8;
    public static final int MESSAGE_RECEIVED = 0x9;
    public static final int NODE_IS_OFFLINE = 0x10;
+    public static final int USERNAME_ISNT_AVAILABLE = 0x11;
+    public static final int USERNAME_AVAILABLE = 0x12;
 }
--- a/app/src/main/java/io/github/chronosx88/influence/logic/ChatListLogic.java
+++ b/app/src/main/java/io/github/chronosx88/influence/logic/ChatListLogic.java
@ -2,11 +2,11 @@ package io.github.chronosx88.influence.logic;

 import java.util.List;

-import io.github.chronosx88.influence.contracts.chatlist.IChatListLogicContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.models.roomEntities.ChatEntity;

-public class ChatListLogic implements IChatListLogicContract {
+public class ChatListLogic implements CoreContracts.IChatListLogicContract {

    @Override
    public List<ChatEntity> loadAllChats() {
--- a/app/src/main/java/io/github/chronosx88/influence/logic/ChatLogic.java
+++ b/app/src/main/java/io/github/chronosx88/influence/logic/ChatLogic.java
@ -13,7 +13,7 @@ import java.util.Timer;
 import java.util.TimerTask;
 import java.util.UUID;

-import io.github.chronosx88.influence.contracts.chatactivity.IChatLogicContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.helpers.KeyPairManager;
 import io.github.chronosx88.influence.helpers.LocalDBWrapper;
@ -27,7 +27,7 @@ import io.github.chronosx88.influence.models.TextMessage;
 import io.github.chronosx88.influence.models.roomEntities.ChatEntity;
 import io.github.chronosx88.influence.models.roomEntities.MessageEntity;

-public class ChatLogic implements IChatLogicContract {
+public class ChatLogic implements CoreContracts.IChatLogicContract {
    private static Gson gson = new Gson();
    private String chatID;
    private String newMessage = "";
--- a/app/src/main/java/io/github/chronosx88/influence/logic/MainLogic.java
+++ b/app/src/main/java/io/github/chronosx88/influence/logic/MainLogic.java
@ -22,6 +22,8 @@ import net.tomp2p.peers.Number160;
 import net.tomp2p.peers.PeerAddress;
 import net.tomp2p.relay.tcp.TCPRelayClientConfig;
 import net.tomp2p.replication.AutoReplication;
+import net.tomp2p.replication.IndirectReplication;
+import net.tomp2p.replication.Replication;
 import net.tomp2p.storage.Data;

 import java.io.IOException;
@ -34,7 +36,7 @@ import java.util.Timer;
 import java.util.TimerTask;
 import java.util.UUID;

-import io.github.chronosx88.influence.contracts.mainactivity.IMainLogicContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.helpers.JVMShutdownHook;
 import io.github.chronosx88.influence.helpers.KeyPairManager;
@ -44,8 +46,8 @@ import io.github.chronosx88.influence.helpers.StorageBerkeleyDB;
 import io.github.chronosx88.influence.helpers.actions.UIActions;
 import io.github.chronosx88.influence.models.PublicUserProfile;

-public class MainLogic implements IMainLogicContract {
-    private static final String LOG_TAG = "MainLogic";
+public class MainLogic implements CoreContracts.IMainLogicContract {
+    private static final String LOG_TAG = MainLogic.class.getName();

    private SharedPreferences preferences;
    private Number160 peerID;
@ -54,7 +56,7 @@ public class MainLogic implements IMainLogicContract {
    private InetAddress bootstrapAddress = null;
    private PeerAddress bootstrapPeerAddress = null;
    private Gson gson;
-    private AutoReplication replication;
+    private IndirectReplication replication;
    private KeyPairManager keyPairManager;
    private Thread checkNewChatsThread = null;
    private StorageBerkeleyDB storage;
@ -142,11 +144,13 @@ public class MainLogic implements IMainLogicContract {
                jsonObject.addProperty("action", UIActions.BOOTSTRAP_SUCCESS);
                AppHelper.getObservable().notifyUIObservers(jsonObject);
                AppHelper.storePeerID(preferences.getString("peerID", null));
+                AppHelper.updateUsername(preferences.getString("username", null));
                AppHelper.storePeerDHT(peerDHT);
                AppHelper.initNetworkHandler();
                setReceiveHandler();
                gson = new Gson();
                publicProfileToDHT();
+                SettingsLogic.Companion.publishUsername(AppHelper.getUsername(), AppHelper.getUsername());
                NetworkHandler.handlePendingChatRequests();
                TimerTask timerTask = new TimerTask() {
                    @Override
@ -163,7 +167,7 @@ public class MainLogic implements IMainLogicContract {
                };
                Timer timer = new Timer();
                timer.schedule(timerTask, 1, 5000);
-                replication = new AutoReplication(peerDHT.peer()).start();
+                replication = new IndirectReplication(peerDHT).start();
            } catch (IOException e) {
                e.printStackTrace();
            }
@ -224,7 +228,7 @@ public class MainLogic implements IMainLogicContract {
    public void shutdownPeer() {
        new Thread(() -> {
            if(replication != null) {
-                replication.shutdown().start();
+                replication.shutdown();
            }
            peerDHT.peer().announceShutdown().start().awaitUninterruptibly();
            peerDHT.peer().shutdown().awaitUninterruptibly();
@ -245,7 +249,7 @@ public class MainLogic implements IMainLogicContract {

    private void publicProfileToDHT() {
        KeyPair mainKeyPair = keyPairManager.openMainKeyPair();
-        PublicUserProfile userProfile = new PublicUserProfile(AppHelper.getPeerID(), peerDHT.peerAddress());
+        PublicUserProfile userProfile = new PublicUserProfile(AppHelper.getUsername(), peerDHT.peerAddress());
        Data serializedUserProfile = null;
        try {
            serializedUserProfile = new Data(gson.toJson(userProfile))
--- a/app/src/main/java/io/github/chronosx88/influence/logic/SettingsLogic.kt
+++ b/app/src/main/java/io/github/chronosx88/influence/logic/SettingsLogic.kt
@ -0,0 +1,46 @@
+package io.github.chronosx88.influence.logic
+
+import android.util.Log
+import io.github.chronosx88.influence.contracts.CoreContracts
+import io.github.chronosx88.influence.helpers.AppHelper
+import io.github.chronosx88.influence.helpers.KeyPairManager
+import io.github.chronosx88.influence.helpers.P2PUtils
+import net.tomp2p.peers.Number640
+import net.tomp2p.storage.Data
+import java.io.IOException
+
+class SettingsLogic : CoreContracts.ISettingsLogic {
+
+    override fun checkUsernameExists(username: String) : Boolean {
+        val usernameMap: MutableMap<Number640, Data>? = P2PUtils.get(username)
+        usernameMap ?: return false
+        return true
+    }
+
+    companion object {
+        private val LOG_TAG: String = "SettingsLogic"
+        private val keyPairManager = KeyPairManager()
+
+        fun publishUsername(oldUsername: String?, username: String?) {
+            val mainKeyPair = keyPairManager.openMainKeyPair()
+            if(oldUsername != null || !oldUsername.equals("")) {
+                P2PUtils.remove(oldUsername, null, mainKeyPair)
+            }
+
+            if (username.equals("") || username == null) {
+                return
+            }
+            var data: Data? = null
+            try {
+                data = Data(AppHelper.getPeerID())
+            } catch (e: IOException) {
+                e.printStackTrace()
+            }
+
+            data!!.protectEntry(mainKeyPair)
+
+            val isSuccess = P2PUtils.put(username, null, data, mainKeyPair)
+            Log.i(LOG_TAG, if (isSuccess) "Username $username is published!" else "Username $username isn't published!")
+        }
+    }
+}
--- a/app/src/main/java/io/github/chronosx88/influence/logic/StartChatLogic.java
+++ b/app/src/main/java/io/github/chronosx88/influence/logic/StartChatLogic.java
@ -13,7 +13,7 @@ import java.util.ArrayList;
 import java.util.Map;
 import java.util.UUID;

-import io.github.chronosx88.influence.contracts.startchat.IStartChatLogicContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.helpers.KeyPairManager;
 import io.github.chronosx88.influence.helpers.LocalDBWrapper;
@ -24,7 +24,7 @@ import io.github.chronosx88.influence.models.ChatMetadata;
 import io.github.chronosx88.influence.models.NewChatRequestMessage;
 import io.github.chronosx88.influence.models.PublicUserProfile;

-public class StartChatLogic implements IStartChatLogicContract {
+public class StartChatLogic implements CoreContracts.IStartChatLogicContract {
    private PeerDHT peerDHT;
    private Gson gson;
    private KeyPairManager keyPairManager;
@ -37,20 +37,25 @@ public class StartChatLogic implements IStartChatLogicContract {
    }

    @Override
-    public void sendStartChatMessage(String peerID) {
+    public void sendStartChatMessage(String username) {
        if(peerDHT == null) {
            ObservableUtils.notifyUI(UIActions.NODE_IS_OFFLINE);
            return;
        }

        new Thread(() -> {
+            String peerID = getPeerIDByUsername(username);
+            if(peerID == null) {
+                ObservableUtils.notifyUI(UIActions.PEER_NOT_EXIST);
+                return;
+            }
            PublicUserProfile recipientPublicProfile = getPublicProfile(peerID);
            if(recipientPublicProfile == null) {
                ObservableUtils.notifyUI(UIActions.PEER_NOT_EXIST);
                return;
            }

-            NewChatRequestMessage newChatRequestMessage = new NewChatRequestMessage(UUID.randomUUID().toString(), UUID.randomUUID().toString(), AppHelper.getPeerID(), AppHelper.getPeerID(), System.currentTimeMillis(), 0);
+            NewChatRequestMessage newChatRequestMessage = new NewChatRequestMessage(UUID.randomUUID().toString(), UUID.randomUUID().toString(), AppHelper.getPeerID(), AppHelper.getUsername(), System.currentTimeMillis(), 0);
            try {
                if(P2PUtils.put(peerID + "_pendingChats", newChatRequestMessage.getChatID(), new Data(gson.toJson(newChatRequestMessage)))) {
                    Log.i(LOG_TAG, "# Create new offline chat request is successful! ChatID: " + newChatRequestMessage.getChatID());
@ -65,13 +70,13 @@ public class StartChatLogic implements IStartChatLogicContract {
            admins.add(AppHelper.getPeerID());
            Data data = null;
            try {
-                data = new Data(gson.toJson(new ChatMetadata(peerID, admins, new ArrayList<>())));
+                data = new Data(gson.toJson(new ChatMetadata(username, admins, new ArrayList<>())));
            } catch (IOException e) {
                e.printStackTrace();
            }
            data.protectEntry(keyPairManager.openMainKeyPair());
            P2PUtils.put(newChatRequestMessage.getChatID() + "_metadata", null, data);
-            LocalDBWrapper.createChatEntry(newChatRequestMessage.getChatID(), peerID, newChatRequestMessage.getChatID() + "_metadata", newChatRequestMessage.getChatID() + "_members", 0);
+            LocalDBWrapper.createChatEntry(newChatRequestMessage.getChatID(), username, newChatRequestMessage.getChatID() + "_metadata", newChatRequestMessage.getChatID() + "_members", 0);
            ObservableUtils.notifyUI(UIActions.NEW_CHAT);
        }).start();
    }
@ -89,4 +94,17 @@ public class StartChatLogic implements IStartChatLogicContract {
        }
        return null;
    }
+
+    private String getPeerIDByUsername(String username) {
+        Map<Number640, Data> usernameMap = P2PUtils.get(username);
+        if(usernameMap == null) {
+            return null;
+        }
+        try {
+            return (String) usernameMap.values().iterator().next().object();
+        } catch (ClassNotFoundException | IOException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
 }
--- a/app/src/main/java/io/github/chronosx88/influence/presenters/ChatListPresenter.java
+++ b/app/src/main/java/io/github/chronosx88/influence/presenters/ChatListPresenter.java
@ -3,9 +3,7 @@ package io.github.chronosx88.influence.presenters;
 import android.content.Intent;
 import android.view.MenuItem;

-import io.github.chronosx88.influence.contracts.chatlist.IChatListLogicContract;
-import io.github.chronosx88.influence.contracts.chatlist.IChatListPresenterContract;
-import io.github.chronosx88.influence.contracts.chatlist.IChatListViewContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.helpers.ChatListAdapter;
 import io.github.chronosx88.influence.helpers.LocalDBWrapper;
@ -13,12 +11,12 @@ import io.github.chronosx88.influence.logic.ChatListLogic;
 import io.github.chronosx88.influence.models.roomEntities.ChatEntity;
 import io.github.chronosx88.influence.views.ChatActivity;

-public class ChatListPresenter implements IChatListPresenterContract {
-    private IChatListViewContract view;
-    private IChatListLogicContract logic;
+public class ChatListPresenter implements CoreContracts.IChatListPresenterContract {
+    private CoreContracts.IChatListViewContract view;
+    private CoreContracts.IChatListLogicContract logic;
    private ChatListAdapter chatListAdapter;

-    public ChatListPresenter(IChatListViewContract view) {
+    public ChatListPresenter(CoreContracts.IChatListViewContract view) {
        this.view = view;
        chatListAdapter = new ChatListAdapter((v, p)-> {
            openChat(chatListAdapter.getChatEntity(p).chatID);
--- a/app/src/main/java/io/github/chronosx88/influence/presenters/ChatPresenter.java
+++ b/app/src/main/java/io/github/chronosx88/influence/presenters/ChatPresenter.java
@ -10,9 +10,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;

-import io.github.chronosx88.influence.contracts.chatactivity.IChatLogicContract;
-import io.github.chronosx88.influence.contracts.chatactivity.IChatPresenterContract;
-import io.github.chronosx88.influence.contracts.chatactivity.IChatViewContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.contracts.observer.IObserver;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.helpers.LocalDBWrapper;
@ -22,14 +20,14 @@ import io.github.chronosx88.influence.logic.ChatLogic;
 import io.github.chronosx88.influence.models.roomEntities.ChatEntity;
 import io.github.chronosx88.influence.models.roomEntities.MessageEntity;

-public class ChatPresenter implements IChatPresenterContract, IObserver {
-    private IChatLogicContract logic;
-    private IChatViewContract view;
+public class ChatPresenter implements CoreContracts.IChatPresenterContract, IObserver {
+    private CoreContracts.IChatLogicContract logic;
+    private CoreContracts.IChatViewContract view;
    private ChatEntity chatEntity;
    private String chatID;
    private Gson gson;

-    public ChatPresenter(IChatViewContract view, String chatID) {
+    public ChatPresenter(CoreContracts.IChatViewContract view, String chatID) {
        this.logic = new ChatLogic(LocalDBWrapper.getChatByChatID(chatID));
        this.view = view;
        this.chatID = chatID;
--- a/app/src/main/java/io/github/chronosx88/influence/presenters/MainPresenter.java
+++ b/app/src/main/java/io/github/chronosx88/influence/presenters/MainPresenter.java
@ -1,15 +1,13 @@
 package io.github.chronosx88.influence.presenters;

-import io.github.chronosx88.influence.contracts.mainactivity.IMainLogicContract;
-import io.github.chronosx88.influence.contracts.mainactivity.IMainPresenterContract;
-import io.github.chronosx88.influence.contracts.mainactivity.IMainViewContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.logic.MainLogic;

-public class MainPresenter implements IMainPresenterContract {
-    private IMainLogicContract logic;
-    private IMainViewContract view;
+public class MainPresenter implements CoreContracts.IMainPresenterContract {
+    private CoreContracts.IMainLogicContract logic;
+    private CoreContracts.IMainViewContract view;

-    public MainPresenter(IMainViewContract view) {
+    public MainPresenter(CoreContracts.IMainViewContract view) {
        this.view = view;
        logic = new MainLogic();
    }
--- a/app/src/main/java/io/github/chronosx88/influence/presenters/SettingsPresenter.kt
+++ b/app/src/main/java/io/github/chronosx88/influence/presenters/SettingsPresenter.kt
@ -0,0 +1,64 @@
+package io.github.chronosx88.influence.presenters
+
+import android.content.SharedPreferences
+import android.os.Handler
+import com.google.gson.JsonObject
+import io.github.chronosx88.influence.R
+import io.github.chronosx88.influence.contracts.CoreContracts
+import io.github.chronosx88.influence.contracts.observer.IObserver
+import io.github.chronosx88.influence.helpers.AppHelper
+import io.github.chronosx88.influence.helpers.ObservableUtils
+import io.github.chronosx88.influence.helpers.actions.UIActions
+import io.github.chronosx88.influence.logic.SettingsLogic
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+
+class SettingsPresenter(private val view: CoreContracts.ISettingsView) : CoreContracts.ISettingsPresenter, IObserver {
+    private val mainThreadHandler: Handler = Handler(AppHelper.getContext().mainLooper)
+    private val logic: SettingsLogic = SettingsLogic()
+
+    init {
+        AppHelper.getObservable().register(this)
+    }
+
+    override fun updateUsername(username: String) {
+        view.loadingScreen(true)
+        GlobalScope.launch {
+            if(!logic.checkUsernameExists(username)) {
+                // Save username in SharedPreferences
+                val editor: SharedPreferences.Editor = AppHelper.getPreferences().edit()
+                val oldUsername = AppHelper.getPreferences().getString("username", null)
+                if(username.equals("")) {
+                    editor.remove("username")
+                } else {
+                    editor.putString("username", username)
+                }
+                editor.apply()
+                AppHelper.updateUsername(if (username.equals("")) null else username)
+
+                // Publish username on DHT network
+                SettingsLogic.publishUsername(oldUsername, username)
+
+                ObservableUtils.notifyUI(UIActions.USERNAME_AVAILABLE)
+            } else {
+                ObservableUtils.notifyUI(UIActions.USERNAME_ISNT_AVAILABLE)
+            }
+        }
+    }
+
+    override fun handleEvent(json: JsonObject) {
+        val post = {
+            when (json.get("action").asInt) {
+                UIActions.USERNAME_AVAILABLE -> {
+                    view.loadingScreen(false)
+                    view.showMessage(AppHelper.getContext().getString(R.string.username_saved))
+                }
+                UIActions.USERNAME_ISNT_AVAILABLE -> {
+                    view.loadingScreen(false)
+                    view.showMessage(AppHelper.getContext().getString(R.string.username_isnt_saved))
+                }
+            }
+        }
+        mainThreadHandler.post(post)
+    }
+}
--- a/app/src/main/java/io/github/chronosx88/influence/presenters/StartChatPresenter.java
+++ b/app/src/main/java/io/github/chronosx88/influence/presenters/StartChatPresenter.java
@ -2,19 +2,17 @@ package io.github.chronosx88.influence.presenters;

 import com.google.gson.JsonObject;

+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.contracts.observer.IObserver;
-import io.github.chronosx88.influence.contracts.startchat.IStartChatLogicContract;
-import io.github.chronosx88.influence.contracts.startchat.IStartChatPresenterContract;
-import io.github.chronosx88.influence.contracts.startchat.IStartChatViewContract;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.helpers.actions.UIActions;
 import io.github.chronosx88.influence.logic.StartChatLogic;

-public class StartChatPresenter implements IStartChatPresenterContract, IObserver {
-    private IStartChatViewContract view;
-    private IStartChatLogicContract logic;
+public class StartChatPresenter implements CoreContracts.IStartChatPresenterContract, IObserver {
+    private CoreContracts.IStartChatViewContract view;
+    private CoreContracts.IStartChatLogicContract logic;

-    public StartChatPresenter(IStartChatViewContract view) {
+    public StartChatPresenter(CoreContracts.IStartChatViewContract view) {
        this.view = view;
        this.logic = new StartChatLogic();
        AppHelper.getObservable().register(this);
--- a/app/src/main/java/io/github/chronosx88/influence/views/ChatActivity.java
+++ b/app/src/main/java/io/github/chronosx88/influence/views/ChatActivity.java
@ -1,95 +0,0 @@
-package io.github.chronosx88.influence.views;
-
-import android.content.Intent;
-import android.os.Bundle;
-import android.view.MenuItem;
-import android.widget.EditText;
-import android.widget.ImageButton;
-import android.widget.TextView;
-
-import java.util.List;
-
-import androidx.annotation.Nullable;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.appcompat.widget.Toolbar;
-import androidx.recyclerview.widget.LinearLayoutManager;
-import androidx.recyclerview.widget.RecyclerView;
-import io.github.chronosx88.influence.R;
-import io.github.chronosx88.influence.contracts.chatactivity.IChatViewContract;
-import io.github.chronosx88.influence.helpers.ChatAdapter;
-import io.github.chronosx88.influence.models.roomEntities.MessageEntity;
-import io.github.chronosx88.influence.presenters.ChatPresenter;
-
-public class ChatActivity extends AppCompatActivity implements IChatViewContract {
-    private ChatAdapter chatAdapter;
-    private RecyclerView messageList;
-    private ImageButton sendMessageButton;
-    private EditText messageTextEdit;
-    private TextView contactUsernameTextView;
-    private ChatPresenter presenter;
-
-    @Override
-    protected void onCreate(@Nullable Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        setContentView(R.layout.activity_chat);
-
-        Intent intent = getIntent();
-
-        presenter = new ChatPresenter(this, intent.getStringExtra("chatID"));
-        Toolbar toolbar = findViewById(R.id.toolbar_chat_activity);
-        setSupportActionBar(toolbar);
-        getSupportActionBar().setTitle("");
-        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
-        getSupportActionBar().setHomeButtonEnabled(true);
-        messageList = findViewById(R.id.message_list);
-        chatAdapter = new ChatAdapter();
-        presenter.updateAdapter();
-        messageList.setAdapter(chatAdapter);
-        messageList.setLayoutManager(new LinearLayoutManager(this));
-        contactUsernameTextView = findViewById(R.id.appbar_username);
-        messageTextEdit = findViewById(R.id.message_input);
-        sendMessageButton = findViewById(R.id.send_button);
-        sendMessageButton.setOnClickListener((v) -> {
-            if(messageTextEdit.getText().toString().equals("")) {
-                return;
-            }
-            presenter.sendMessage(messageTextEdit.getText().toString());
-            messageTextEdit.setText("");
-            messageList.scrollToPosition(chatAdapter.getItemCount()-1);
-        });
-        contactUsernameTextView.setText(intent.getStringExtra("contactUsername"));
-        messageList.scrollToPosition(chatAdapter.getItemCount()-1);
-    }
-
-    @Override
-    public void updateMessageList(MessageEntity message) {
-        runOnUiThread(() -> {
-            chatAdapter.addMessage(message);
-            chatAdapter.notifyDataSetChanged();
-        });
-    }
-
-    @Override
-    public void updateMessageList(List<MessageEntity> messages) {
-        runOnUiThread(() -> {
-            chatAdapter.addMessages(messages);
-            chatAdapter.notifyDataSetChanged();
-        });
-    }
-
-    @Override
-    public boolean onOptionsItemSelected(MenuItem item) {
-        switch(item.getItemId()) {
-            case android.R.id.home:
-                finish();
-                return true;
-        }
-        return super.onOptionsItemSelected(item);
-    }
-
-    @Override
-    protected void onDestroy() {
-        super.onDestroy();
-        presenter.onDestroy();
-    }
-}
--- a/app/src/main/java/io/github/chronosx88/influence/views/ChatActivity.kt
+++ b/app/src/main/java/io/github/chronosx88/influence/views/ChatActivity.kt
@ -0,0 +1,86 @@
+package io.github.chronosx88.influence.views
+
+import android.os.Bundle
+import android.view.MenuItem
+import android.widget.EditText
+import android.widget.ImageButton
+import android.widget.TextView
+import androidx.appcompat.app.AppCompatActivity
+import androidx.appcompat.widget.Toolbar
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import io.github.chronosx88.influence.R
+import io.github.chronosx88.influence.contracts.CoreContracts
+import io.github.chronosx88.influence.helpers.ChatAdapter
+import io.github.chronosx88.influence.models.roomEntities.MessageEntity
+import io.github.chronosx88.influence.presenters.ChatPresenter
+
+class ChatActivity : AppCompatActivity(), CoreContracts.IChatViewContract {
+    private var chatAdapter: ChatAdapter? = null
+    private var messageList: RecyclerView? = null
+    private var sendMessageButton: ImageButton? = null
+    private var messageTextEdit: EditText? = null
+    private var contactUsernameTextView: TextView? = null
+    private var presenter: ChatPresenter? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_chat)
+
+        val intent = intent
+
+        presenter = ChatPresenter(this, intent.getStringExtra("chatID"))
+        val toolbar = findViewById<Toolbar>(R.id.toolbar_chat_activity)
+        setSupportActionBar(toolbar)
+        supportActionBar!!.setTitle("")
+        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
+        supportActionBar!!.setHomeButtonEnabled(true)
+        messageList = findViewById(R.id.message_list)
+        chatAdapter = ChatAdapter()
+        presenter!!.updateAdapter()
+        messageList!!.adapter = chatAdapter
+        messageList!!.layoutManager = LinearLayoutManager(this)
+        contactUsernameTextView = findViewById(R.id.appbar_username)
+        messageTextEdit = findViewById(R.id.message_input)
+        sendMessageButton = findViewById(R.id.send_button)
+        sendMessageButton!!.setOnClickListener sendMessageButton@{
+            if (messageTextEdit!!.text.toString() == "") {
+                return@sendMessageButton
+            }
+            presenter!!.sendMessage(messageTextEdit!!.text.toString())
+            messageTextEdit!!.setText("")
+            messageList!!.scrollToPosition(chatAdapter!!.itemCount - 1)
+        }
+        contactUsernameTextView!!.text = intent.getStringExtra("contactUsername")
+        messageList!!.scrollToPosition(chatAdapter!!.itemCount - 1)
+    }
+
+    override fun updateMessageList(message: MessageEntity) {
+        runOnUiThread {
+            chatAdapter!!.addMessage(message)
+            chatAdapter!!.notifyDataSetChanged()
+        }
+    }
+
+    override fun updateMessageList(messages: List<MessageEntity>) {
+        runOnUiThread {
+            chatAdapter!!.addMessages(messages)
+            chatAdapter!!.notifyDataSetChanged()
+        }
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        when (item.itemId) {
+            android.R.id.home -> {
+                finish()
+                return true
+            }
+        }
+        return super.onOptionsItemSelected(item)
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        presenter!!.onDestroy()
+    }
+}
--- a/app/src/main/java/io/github/chronosx88/influence/views/MainActivity.java
+++ b/app/src/main/java/io/github/chronosx88/influence/views/MainActivity.java
@ -13,8 +13,7 @@ import androidx.appcompat.app.AppCompatActivity;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentTransaction;
 import io.github.chronosx88.influence.R;
-import io.github.chronosx88.influence.contracts.mainactivity.IMainPresenterContract;
-import io.github.chronosx88.influence.contracts.mainactivity.IMainViewContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.contracts.observer.IObserver;
 import io.github.chronosx88.influence.helpers.AppHelper;
 import io.github.chronosx88.influence.helpers.actions.UIActions;
@ -23,9 +22,9 @@ import io.github.chronosx88.influence.views.fragments.ChatListFragment;
 import io.github.chronosx88.influence.views.fragments.SettingsFragment;
 import io.github.chronosx88.influence.views.fragments.StartChatFragment;

-public class MainActivity extends AppCompatActivity implements IObserver, IMainViewContract {
+public class MainActivity extends AppCompatActivity implements IObserver, CoreContracts.IMainViewContract {

-    private IMainPresenterContract presenter;
+    private CoreContracts.IMainPresenterContract presenter;
    private ProgressDialog progressDialog;
    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
            = new BottomNavigationView.OnNavigationItemSelectedListener() {
--- a/app/src/main/java/io/github/chronosx88/influence/views/fragments/ChatListFragment.java
+++ b/app/src/main/java/io/github/chronosx88/influence/views/fragments/ChatListFragment.java
@ -1,92 +0,0 @@
-package io.github.chronosx88.influence.views.fragments;
-
-import android.os.Bundle;
-import android.os.Handler;
-import android.view.LayoutInflater;
-import android.view.MenuItem;
-import android.view.View;
-import android.view.ViewGroup;
-
-import com.google.gson.JsonObject;
-
-import java.util.List;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.fragment.app.Fragment;
-import androidx.recyclerview.widget.LinearLayoutManager;
-import androidx.recyclerview.widget.RecyclerView;
-import io.github.chronosx88.influence.R;
-import io.github.chronosx88.influence.contracts.chatlist.IChatListPresenterContract;
-import io.github.chronosx88.influence.contracts.chatlist.IChatListViewContract;
-import io.github.chronosx88.influence.contracts.observer.IObserver;
-import io.github.chronosx88.influence.helpers.AppHelper;
-import io.github.chronosx88.influence.helpers.ChatListAdapter;
-import io.github.chronosx88.influence.helpers.actions.UIActions;
-import io.github.chronosx88.influence.models.roomEntities.ChatEntity;
-import io.github.chronosx88.influence.presenters.ChatListPresenter;
-
-public class ChatListFragment extends Fragment implements IChatListViewContract, IObserver {
-    private IChatListPresenterContract presenter;
-    private RecyclerView chatList;
-    private Handler mainThreadHandler;
-
-    @Override
-    public void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        AppHelper.getObservable().register(this);
-        this.mainThreadHandler = new Handler(getContext().getMainLooper());
-    }
-
-    @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container,
-                             Bundle savedInstanceState) {
-        return inflater.inflate(R.layout.chatlist_fragment, container, false);
-    }
-
-    @Override
-    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
-        super.onViewCreated(view, savedInstanceState);
-        chatList = view.findViewById(R.id.chatlist_container);
-        chatList.setLayoutManager(new LinearLayoutManager(getContext()));
-        presenter = new ChatListPresenter(this);
-        presenter.updateChatList();
-        registerForContextMenu(chatList);
-    }
-
-    @Override
-    public void setRecycleAdapter(ChatListAdapter adapter) {
-        chatList.setAdapter(adapter);
-    }
-
-    @Override
-    public void onResume() {
-        super.onResume();
-        presenter.updateChatList();
-    }
-
-    @Override
-    public void handleEvent(JsonObject object) {
-        switch (object.get("action").getAsInt()) {
-            case UIActions.SUCCESSFUL_CREATE_CHAT:
-            case UIActions.NEW_CHAT: {
-                presenter.updateChatList();
-                break;
-            }
-        }
-    }
-
-    @Override
-    public void updateChatList(ChatListAdapter adapter, List<ChatEntity> chats) {
-        mainThreadHandler.post(() -> {
-            adapter.setChatList(chats);
-            adapter.notifyDataSetChanged();
-        });
-    }
-
-    @Override
-    public boolean onContextItemSelected(@NonNull MenuItem item) {
-        presenter.onContextItemSelected(item);
-        return super.onContextItemSelected(item);
-    }
-}
--- a/app/src/main/java/io/github/chronosx88/influence/views/fragments/ChatListFragment.kt
+++ b/app/src/main/java/io/github/chronosx88/influence/views/fragments/ChatListFragment.kt
@ -0,0 +1,76 @@
+package io.github.chronosx88.influence.views.fragments
+
+import android.os.Bundle
+import android.os.Handler
+import android.view.LayoutInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
+
+import com.google.gson.JsonObject
+import androidx.fragment.app.Fragment
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import io.github.chronosx88.influence.R
+import io.github.chronosx88.influence.contracts.CoreContracts
+import io.github.chronosx88.influence.contracts.observer.IObserver
+import io.github.chronosx88.influence.helpers.AppHelper
+import io.github.chronosx88.influence.helpers.ChatListAdapter
+import io.github.chronosx88.influence.helpers.actions.UIActions
+import io.github.chronosx88.influence.models.roomEntities.ChatEntity
+import io.github.chronosx88.influence.presenters.ChatListPresenter
+
+class ChatListFragment : Fragment(), CoreContracts.IChatListViewContract, IObserver {
+    private var presenter: CoreContracts.IChatListPresenterContract? = null
+    private var chatList: RecyclerView? = null
+    private var mainThreadHandler: Handler? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        AppHelper.getObservable().register(this)
+        this.mainThreadHandler = Handler(context!!.mainLooper)
+    }
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+        return inflater.inflate(R.layout.chatlist_fragment, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        chatList = view.findViewById(R.id.chatlist_container)
+        chatList!!.layoutManager = LinearLayoutManager(context)
+        presenter = ChatListPresenter(this)
+        presenter!!.updateChatList()
+        registerForContextMenu(chatList!!)
+    }
+
+    override fun setRecycleAdapter(adapter: ChatListAdapter) {
+        chatList!!.adapter = adapter
+    }
+
+    override fun onResume() {
+        super.onResume()
+        presenter!!.updateChatList()
+    }
+
+    override fun handleEvent(`object`: JsonObject) {
+        when (`object`.get("action").asInt) {
+            UIActions.SUCCESSFUL_CREATE_CHAT, UIActions.NEW_CHAT -> {
+                presenter!!.updateChatList()
+            }
+        }
+    }
+
+    override fun updateChatList(adapter: ChatListAdapter, chats: List<ChatEntity>) {
+        mainThreadHandler!!.post {
+            adapter.setChatList(chats)
+            adapter.notifyDataSetChanged()
+        }
+    }
+
+    override fun onContextItemSelected(item: MenuItem): Boolean {
+        presenter!!.onContextItemSelected(item)
+        return super.onContextItemSelected(item)
+    }
+}
--- a/app/src/main/java/io/github/chronosx88/influence/views/fragments/SettingsFragment.java
+++ b/app/src/main/java/io/github/chronosx88/influence/views/fragments/SettingsFragment.java
@ -1,19 +1,33 @@
 package io.github.chronosx88.influence.views.fragments;

+import android.app.AlertDialog;
+import android.app.ProgressDialog;
 import android.content.ClipData;
 import android.content.ClipboardManager;
 import android.content.Context;
 import android.os.Bundle;
+import android.widget.EditText;
+import android.widget.LinearLayout;
 import android.widget.Toast;

+import org.jetbrains.annotations.NotNull;
+
 import androidx.preference.PreferenceFragmentCompat;
 import io.github.chronosx88.influence.R;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.helpers.AppHelper;
+import io.github.chronosx88.influence.presenters.SettingsPresenter;

-public class SettingsFragment extends PreferenceFragmentCompat {
+public class SettingsFragment extends PreferenceFragmentCompat implements CoreContracts.ISettingsView {
+    private ProgressDialog progressDialog;
+    private SettingsPresenter presenter;

    @Override
    public void onCreatePreferences(Bundle bundle, String s) {
+        progressDialog = new ProgressDialog(getContext(), R.style.AlertDialogTheme);
+        progressDialog.setCancelable(false);
+        progressDialog.setProgressStyle(android.R.style.Widget_ProgressBar_Small);
+        presenter = new SettingsPresenter(this);
        // Load the Preferences from the XML file
        addPreferencesFromResource(R.xml.main_settings);
        getPreferenceScreen().getPreference(0).setSummary(AppHelper.getPeerID());
@ -24,5 +38,42 @@ public class SettingsFragment extends PreferenceFragmentCompat {
            Toast.makeText(AppHelper.getContext(), "Скопировано в буфер обмена!", Toast.LENGTH_SHORT).show();
            return false;
        }));
+        getPreferenceScreen().getPreference(1).setSummary(AppHelper.getUsername());
+        getPreferenceScreen().getPreference(1).setOnPreferenceClickListener((v) -> {
+            setupUsernameEditDialog().show();
+            return true;
+        });
+    }
+
+    @Override
+    public void loadingScreen(boolean state) {
+        if(state)
+            progressDialog.show();
+        else
+            progressDialog.dismiss();
+    }
+
+    @Override
+    public void showMessage(@NotNull String message) {
+        Toast.makeText(AppHelper.getContext(), message, Toast.LENGTH_LONG).show();
+    }
+
+    private AlertDialog.Builder setupUsernameEditDialog() {
+        AlertDialog.Builder alertDialog = new AlertDialog.Builder(getContext());
+        alertDialog.setTitle(getContext().getString(R.string.username_settings));
+
+        final EditText input = new EditText(getContext());
+        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
+                LinearLayout.LayoutParams.MATCH_PARENT,
+                LinearLayout.LayoutParams.MATCH_PARENT);
+        input.setSingleLine();
+        input.setLayoutParams(lp);
+        alertDialog.setView(input);
+
+        alertDialog.setPositiveButton(getContext().getString(R.string.ok), (dialog, which) -> presenter.updateUsername(input.getText().toString()));
+
+        alertDialog.setNegativeButton(getContext().getString(R.string.cancel), (dialog, which) -> dialog.cancel());
+
+        return alertDialog;
    }
 }
--- a/app/src/main/java/io/github/chronosx88/influence/views/fragments/StartChatFragment.java
+++ b/app/src/main/java/io/github/chronosx88/influence/views/fragments/StartChatFragment.java
@ -16,10 +16,10 @@ import androidx.annotation.Nullable;
 import androidx.coordinatorlayout.widget.CoordinatorLayout;
 import androidx.fragment.app.Fragment;
 import io.github.chronosx88.influence.R;
-import io.github.chronosx88.influence.contracts.startchat.IStartChatViewContract;
+import io.github.chronosx88.influence.contracts.CoreContracts;
 import io.github.chronosx88.influence.presenters.StartChatPresenter;

-public class StartChatFragment extends Fragment implements IStartChatViewContract {
+public class StartChatFragment extends Fragment implements CoreContracts.IStartChatViewContract {
    private TextInputLayout textInputPeerID;
    private ProgressDialog progressDialog;
    private Button createChatButton;
--- a/app/src/main/res/layout/start_chat_fragment.xml
+++ b/app/src/main/res/layout/start_chat_fragment.xml
@ -20,7 +20,7 @@
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
-                android:hint="Peer ID"/>
+                android:hint="@string/username_hint"/>
        </com.google.android.material.textfield.TextInputLayout>

        <Button
--- a/app/src/main/res/values-ru-rRU/strings.xml
+++ b/app/src/main/res/values-ru-rRU/strings.xml
@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_name">Influence</string>
+    <string name="username_saved">Ваше имя пользователя успешно сохранено!</string>
+    <string name="username_isnt_saved">К сожалению, это имя пользователя занято.</string>
+    <string name="ok">OK</string>
+    <string name="cancel">Отмена</string>
+    <string name="username_settings">Ваше имя пользователя</string>
+    <string name="username_hint">Имя пользователя</string>
+</resources>
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@ -1,3 +1,9 @@
 <resources>
    <string name="app_name">Influence</string>
+    <string name="username_saved">Your username saved successfully!</string>
+    <string name="username_isnt_saved">Sorry, this username is busy.</string>
+    <string name="ok">OK</string>
+    <string name="cancel">Cancel</string>
+    <string name="username_settings">Your username</string>
+    <string name="username_hint">Username</string>
 </resources>
--- a/app/src/main/res/xml/main_settings.xml
+++ b/app/src/main/res/xml/main_settings.xml
@ -4,6 +4,10 @@
        android:key="peerID"
        android:title="Мой Peer ID"
        android:summary=""/>
+    <Preference
+        android:key="username"
+        android:title="Мой username"
+        android:summary=""/>
    <EditTextPreference
        android:key="bootstrapAddress"
        android:title="Адрес Bootstrap-ноды"
--- a/build.gradle
+++ b/build.gradle
@ -1,7 +1,7 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.

 buildscript {
-    ext.kotlin_version = '1.3.21'
+    ext.kotlin_version = '1.3.30'
    repositories {
        google()
        jcenter()