A decentralized, peer-to-peer messaging app for Android that operates over Bluetooth Low Energy mesh networks. Based on the original BitChat protocol by jackjackbits.

• 🔐 End-to-End Encryption: X25519 key exchange + AES-256-GCM
• 📡 Bluetooth LE Mesh: No internet required, works completely offline
• 🚫 No Servers: Pure peer-to-peer communication
• 🏠 Room-Based Chat: Join or create topic-based chat rooms
• 💬 Private Messages: Encrypted direct messaging between users
• 🔄 Store & Forward: Messages cached for offline peers
• 🎭 Anonymous: No accounts, phone numbers, or persistent identifiers
• ⚡ IRC-Style Commands: Familiar /join, /msg, /who interface
• 🎨 Material Design 3: Modern Android UI with dynamic theming
• 🔋 Battery Optimized: Adaptive scanning and power management

• Android Studio Hedgehog or newer
• Android device with Bluetooth LE support
• Minimum SDK: Android 8.0 (API 26)
• Target SDK: Android 14 (API 34)

1. Clone this repository to your Projects folder
2. Open in Android Studio
3. Sync Gradle files
4. Run on your Android device

# Debug build
./gradlew assembleDebug

# Release build
./gradlew assembleRelease

• /j #room - Join or create a room
• /m @user message - Send private message
• /w - List online users
• /rooms - Show all rooms
• /nick newname - Change nickname
• /clear - Clear chat messages
• /help - Show all commands

1. Launch the app - it will auto-generate a random nickname
2. Grant Bluetooth and location permissions when prompted
3. The app automatically scans for nearby BitChat peers
4. Join the default #general room or create your own
5. Start chatting with nearby users!

┌─────────────────────────────────────┐
│           Application Layer         │
│     (Chat UI, Commands, Rooms)      │
├─────────────────────────────────────┤
│            Service Layer            │
│  (Encryption, Retry, Compression)   │
├─────────────────────────────────────┤
│         Mesh Network Layer          │
│    (Routing, Relay, Store & Forward) │
├─────────────────────────────────────┤
│          Transport Layer            │
│   (Binary Protocol, BLE GATT)      │
└─────────────────────────────────────┘

• MainActivity: Main UI using Jetpack Compose
• ChatViewModel: Manages chat state and user interactions
• BleMeshService: Bluetooth LE mesh networking
• EncryptionService: End-to-end encryption and key management
• MeshMessage: Protocol data structures

• Private Messages: X25519 ECDH + AES-256-GCM
• Room Messages: Argon2id password derivation + AES-256-GCM
• Digital Signatures: Ed25519 for message authenticity
• Forward Secrecy: New key pairs generated each session
• Cover Traffic: Random dummy messages prevent traffic analysis

This Android implementation is compatible with the original iOS BitChat:

• Same Bluetooth service UUIDs
• Identical binary packet format
• Compatible encryption algorithms
• Cross-platform messaging support

app/src/main/java/com/bitchat/android/
├── MainActivity.kt              # Main activity
├── ChatViewModel.kt             # Chat state management
├── mesh/
│   └── BleMeshService.kt       # Bluetooth LE mesh networking
├── crypto/
│   └── EncryptionService.kt    # Encryption and security
└── ui/theme/
    ├── Theme.kt                # Material Design 3 theme
    └── Typography.kt           # Typography scale

• Kotlin: Primary development language
• Jetpack Compose: Modern Android UI toolkit
• Material Design 3: Google's latest design system
• Bluetooth LE: Low energy mesh networking
• BouncyCastle: Cryptographic operations
• Coroutines: Asynchronous programming

This project follows the same open principles as the original BitChat:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test on real devices
5. Submit a pull request

Released into the public domain, same as the original BitChat.

• Original BitChat protocol by jackjackbits
• Material Design 3 by Google
• Bluetooth LE mesh networking concepts

App crashes on startup

• Ensure Bluetooth permissions are granted
• Check that device supports Bluetooth LE

No peers discovered

• Verify location permissions (required for BLE scanning)
• Try moving closer to other BitChat users
• Check Bluetooth is enabled

Messages not sending

• Ensure connected to at least one peer
• Check message format (avoid special characters)
• Try rejoining the room

For development, use the debug build which includes:

• Extended logging
• Debug manifest with .debug suffix
• Additional debugging tools

./gradlew assembleDebug
adb install app/build/outputs/apk/debug/app-debug.apk

BitChat Android - Bringing decentralized mesh communication to Android devices.