Kotlogram works, login is working.

.gitignore

@@ -0,0 +1,5 @@
+build/
+.rgadle/
+.gradle/
+auth.dat
+dc.dat

build.gradle

@@ -1 +1,29 @@
 apply plugin: 'java'
+apply plugin: 'application'
+
+mainClassName= 'de.fabianonline.telegram_backup.Main'
+
+repositories {
+	mavenCentral()
+	maven { 
+		url "https://jitpack.io"
+	}
+}
+
+dependencies {
+	compile 'com.github.badoualy:kotlogram:0.0.6'
+}
+
+run {
+	standardInput = System.in
+}
+
+jar {
+	manifest {
+		attributes "Main-Class": "$mainClassName"
+	}
+	
+	from {
+		configurations.compile.collect { it.isDirectory() ? it : zipTree(it) }
+	}
+}

src/de/fabianonline/telegram_backup/Main.java

@@ -1,7 +0,0 @@
-package de.fabianonline.telegram_backup;
-
-public class Main {
-	public static void main(String[] args) {
-		System.out.println("Hello World");
-	}
-}

src/main/java/de/fabianonline/telegram_backup/ApiStorage.java

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+package de.fabianonline.telegram_backup;
+
+import com.github.badoualy.telegram.api.TelegramApiStorage;
+import com.github.badoualy.telegram.mtproto.DataCenter;
+import com.github.badoualy.telegram.mtproto.auth.AuthKey;
+
+import org.apache.commons.io.FileUtils;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+class ApiStorage implements TelegramApiStorage {
+	public void saveAuthKey(AuthKey authKey) { 
+		try {
+			FileUtils.writeByteArrayToFile(Config.FILE_AUTH_KEY, authKey.getKey());
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+	
+	public AuthKey loadAuthKey() {
+		try {
+			return new AuthKey(FileUtils.readFileToByteArray(Config.FILE_AUTH_KEY));
+		} catch (IOException e) {
+			if (!(e instanceof FileNotFoundException)) e.printStackTrace();
+		}
+		
+		return null;
+	}
+	
+	public void saveDc(DataCenter dc) {
+		try {
+			FileUtils.write(Config.FILE_DC, dc.toString());
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+	
+	public DataCenter loadDc() {
+		try {
+			String[] infos = FileUtils.readFileToString(Config.FILE_DC).split(":");
+			return new DataCenter(infos[0], Integer.parseInt(infos[1]));
+		} catch (IOException e) {
+			if (!(e instanceof FileNotFoundException)) e.printStackTrace();
+		}
+		return null;
+	}
+	
+	public void deleteAuthKey() {
+		try {
+			FileUtils.forceDelete(Config.FILE_AUTH_KEY);
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+	
+	public void deleteDc() {
+		try {
+			FileUtils.forceDelete(Config.FILE_DC);
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+	
+	public void saveServerSalt(long salt) {}
+	
+	public Long loadServerSalt() { return null; }
+}

src/main/java/de/fabianonline/telegram_backup/Config.java

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+package de.fabianonline.telegram_backup;
+
+import java.io.File;
+
+class Config {
+	public static final int APP_ID = 32860;
+	public static final String APP_HASH = "16e4ff955cd0adfc058f95ca564f562d";
+    public static final String APP_MODEL = "Desktop";
+    public static final String APP_SYSVER = "1.0";
+    public static final String APP_APPVER = "0.1";
+    public static final String APP_LANG = "en";
+
+    public static final File FILE_AUTH_KEY = new File("auth.dat");
+    public static final File FILE_DC = new File("dc.dat");
+    public static final File FILE_SALT = new File("salt.dat");
+}
+

src/main/java/de/fabianonline/telegram_backup/Main.java

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+package de.fabianonline.telegram_backup;
+
+import com.github.badoualy.telegram.api.Kotlogram;
+import com.github.badoualy.telegram.api.TelegramApp;
+import com.github.badoualy.telegram.api.TelegramClient;
+import com.github.badoualy.telegram.tl.exception.RpcErrorException;
+
+import de.fabianonline.telegram_backup.Config;
+import de.fabianonline.telegram_backup.ApiStorage;
+import de.fabianonline.telegram_backup.UserManager;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Scanner;
+
+public class Main {
+	public static TelegramApp app = new TelegramApp(Config.APP_ID, Config.APP_HASH, Config.APP_MODEL, Config.APP_SYSVER, Config.APP_APPVER, Config.APP_LANG);
+	public static UserManager user = null;
+	
+	public static void main(String[] args) {
+		System.out.println("Hello World");
+		
+		Kotlogram.setDebugLogEnabled(true);
+		
+		TelegramClient client = Kotlogram.getDefaultClient(app, new ApiStorage());
+		
+		try {
+			user = new UserManager(client);
+			
+			if (!user.isLoggedIn()) {
+				System.out.println("Please enter your phone number in international format.");
+				System.out.println("Example: +4917077651234");
+				System.out.print("> ");
+				String phone = new Scanner(System.in).nextLine();
+				user.sendCodeToPhoneNumber(phone);
+				
+				System.out.println("Telegram sent you a code. Please enter it here.");
+				System.out.print("> ");
+				String code = new Scanner(System.in).nextLine();
+				user.verifyCode(code);
+				
+				if (user.isPasswordNeeded()) {
+					System.out.println("We also need your account password.");
+					System.out.print("> ");
+					String pw = new Scanner(System.in).nextLine();
+					user.verifyPassword(pw);
+				}
+			}
+			
+			System.out.println("You are now signed in as " + user.getUserString());
+		} catch (RpcErrorException e) {
+			e.printStackTrace();
+		} catch (IOException e) {
+			e.printStackTrace();
+		} finally {
+			client.close();
+		}
+		System.out.println("----- EXIT -----");
+	}
+}

src/main/java/de/fabianonline/telegram_backup/TLRequestAccountGetPasswordWithCurrentSalt.java

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+package de.fabianonline.telegram_backup;
+
+import com.github.badoualy.telegram.tl.TLContext;
+import com.github.badoualy.telegram.tl.api.account.TLPassword;
+import com.github.badoualy.telegram.tl.core.TLMethod;
+import com.github.badoualy.telegram.tl.core.TLObject;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import static com.github.badoualy.telegram.tl.StreamUtils.readTLObject;
+
+public class TLRequestAccountGetPasswordWithCurrentSalt extends TLMethod<TLPassword> {
+    public static final int CONSTRUCTOR_ID = 0x548a30f5;
+    private final String _constructor = "account.getPassword#548a30f5";
+    public TLRequestAccountGetPasswordWithCurrentSalt() {}
+    public TLPassword deserializeResponse(InputStream stream, TLContext context) throws IOException {
+        final TLObject response = readTLObject(stream, context);
+        if (response == null) {
+            throw new IOException("Unable to parse response");
+        }
+        if (!(response instanceof TLPassword)) {
+            throw new IOException("Incorrect response type, expected getClass().getCanonicalName(), found response.getClass().getCanonicalName()");
+        }
+        return (TLPassword) response;
+    }
+    public String toString() { return _constructor; }
+    public int getConstructorId() { return CONSTRUCTOR_ID; }
+}

src/main/java/de/fabianonline/telegram_backup/UserManager.java

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+package de.fabianonline.telegram_backup;
+
+import com.github.badoualy.telegram.api.TelegramClient;
+import com.github.badoualy.telegram.tl.api.auth.TLAbsSentCode;
+import com.github.badoualy.telegram.tl.api.auth.TLAuthorization;
+import com.github.badoualy.telegram.tl.api.TLUser;
+import com.github.badoualy.telegram.tl.api.TLUserFull;
+import com.github.badoualy.telegram.tl.api.TLInputUserSelf;
+import com.github.badoualy.telegram.tl.api.account.TLPassword;
+import com.github.badoualy.telegram.tl.exception.RpcErrorException;
+import com.github.badoualy.telegram.tl.core.TLBytes;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.io.IOException;
+
+class UserManager {
+	public TLUser user = null;
+	public String phone = null;
+	private String code = null;
+	private TelegramClient client = null;
+	private TLAbsSentCode sent_code = null;
+	private TLAuthorization auth = null;
+	private boolean password_needed = false;
+	
+	public UserManager(TelegramClient c) throws IOException {
+		this.client = c;
+		try {
+			TLUserFull full_user = this.client.usersGetFullUser(new TLInputUserSelf());
+			this.user = full_user.getUser().getAsUser();
+		} catch (Exception e) {
+			// This may happen. Ignoring it.
+		}
+	}
+	
+	public boolean isLoggedIn() { return user!=null; }
+	
+	public void sendCodeToPhoneNumber(String number) throws RpcErrorException, IOException {
+		this.phone = number;
+		this.sent_code = this.client.authSendCode(this.phone, 5);
+	}
+	
+	public void verifyCode(String code) throws RpcErrorException, IOException {
+		this.code = code;
+		try {
+			this.auth = client.authSignIn(phone, this.sent_code.getPhoneCodeHash(), this.code);
+			this.user = auth.getUser().getAsUser();
+		} catch (RpcErrorException e) {
+			if (!e.getTag().equals("401: SESSION_PASSWORD_NEEDED")) throw e;
+			this.password_needed = true;
+		}
+	}
+	
+	public boolean isPasswordNeeded() { return this.password_needed; }
+	
+	public void verifyPassword(String pw) throws RpcErrorException, IOException {
+		byte[] password = pw.getBytes("UTF-8");
+		byte[] salt = ((TLPassword)client.executeRpcQuery(new TLRequestAccountGetPasswordWithCurrentSalt())).getCurrentSalt().getData();
+		MessageDigest md = null;
+		try {
+			md = MessageDigest.getInstance("SHA-256");
+		} catch (NoSuchAlgorithmException e) {
+			e.printStackTrace();
+			return;
+		}
+		byte[] salted = new byte[2*salt.length + password.length];
+		System.arraycopy(salt,     0, salted, 0,                           salt.length);
+		System.arraycopy(password, 0, salted, salt.length,                 password.length);
+		System.arraycopy(salt,     0, salted, salt.length+password.length, salt.length);
+		byte[] hash = md.digest(salted);
+		auth = client.authCheckPassword(new TLBytes(hash));
+		this.user = auth.getUser().getAsUser();
+	}
+	
+	public String getUserString() {
+		if (this.user==null) return "Not logged in";
+		StringBuilder sb = new StringBuilder();
+		if (this.user.getFirstName()!=null) {
+			sb.append(this.user.getFirstName());
+		}
+		if (this.user.getLastName()!=null) {
+			sb.append(" ");
+			sb.append(this.user.getLastName());
+		}
+		if (this.user.getUsername()!=null) {
+			sb.append(" (@");
+			sb.append(this.user.getUsername());
+			sb.append(")");
+		}
+		return sb.toString();
+	}
+}