Zemzeme

Private, serverless messaging — no accounts, no internet required.

Zemzeme is a fork of bitchat (v1.7.0) for Android, extended with a second internet-capable transport layer built on libp2p. It supports three independent communication methods that can operate simultaneously: offline Bluetooth mesh, direct peer-to-peer over the internet (via libp2p + ICE), and relay-based messaging via the Nostr protocol. All messages are end-to-end encrypted. No registration, no phone number, no central server.

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Zemzeme stands on the shoulders of the bitchat team and its contributors. The core BLE mesh architecture, Noise protocol integration, gossip-based relay, and the original application design are their work. We are grateful for their commitment to open, private, decentralised communication.

Forked from bitchat v1.7.0

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Features

Messaging

• Text messages with formatting and @mention support
• Voice notes (compressed audio)
• Image and file sharing (chunked binary transfer)
• Read receipts and delivery indicators
• Password-protected channels

Transport Layers

Layer	Medium	Internet Required
BLE Mesh	Bluetooth LE	No
P2P / ICE	Wi-Fi / Mobile	Yes
Nostr	Wi-Fi / Mobile (relay)	Yes

All three layers operate simultaneously; the app routes messages through whichever paths are available and falls back automatically.

Location & Channels

• Geohash-based public channels (city → country granularity)
• Custom named group chats
• Geographic group auto-discovery

Security

• Noise Protocol (Noise_NK, Curve25519 + ChaCha20-Poly1305) for all peer sessions
• Ed25519 signed QR codes for peer identity verification
• BouncyCastle PBKDF2 PIN hashing
• EncryptedSharedPreferences (AES-256-GCM) for all local secrets
• Biometric + PIN app lock (optional)
• No GPS coordinates transmitted — only coarse geohash

Privacy

• No account or phone number required
• Zero central server; all state is local or peer-to-peer
• BLE mesh relays use hop-by-hop encryption
• Tor integration (optional, in progress)

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Architecture

┌──────────────────────────────────────────────────────────┐
│                    Jetpack Compose UI                    │
├──────────────────────────────────────────────────────────┤
│                      ChatViewModel                       │
├───────────────────┬──────────────────┬───────────────────┤
│     BLE Mesh      │  P2P (libp2p)    │      Nostr        │
│                   │                  │                   │
│ BluetoothMesh     │ P2PTransport     │ NostrTransport    │
│ Service           │ P2PLibraryRepo   │ NostrRelayManager │
│                   │ golib.aar (Go)   │ NostrClient       │
├───────────────────┴──────────────────┴───────────────────┤
│              EncryptionService (Noise Protocol)          │
│              NoiseEncryptionService                      │
└──────────────────────────────────────────────────────────┘

BLE Mesh

The original bitchat mesh engine. Devices discover each other via BLE advertising and scanning, exchange messages over GATT, and relay packets through nearby devices using TTL-based store-and-forward. Duplicate suppression uses a GCS Bloom filter (Gossip Sync).

P2P Transport (libp2p)

An additional transport layer, unique to this fork. A pre-compiled Go library (golib.aar) built with gomobile wraps libp2p — the open-source peer-to-peer networking library originally developed by Protocol Labs and used by IPFS, Filecoin, and Ethereum 2. It provides:

• Direct ICE connections between peers through NATs and firewalls (no relay server needed once connected)
• DHT peer discovery using the IPFS bootstrap network
• GossipSub pub/sub for topic-based channels
• Media chunking — files split into ≤ 200 KB chunks sent in parallel

libp2p is an independent open-source project. Source: https://libp2p.io · GitHub: libp2p/go-libp2p

Nostr Transport

Uses the Nostr protocol for relay-based messaging. Supports private DMs (Curve25519-XChaCha20-Poly1305), geohash channels, proof-of-work, and fragment reassembly for large messages.

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Requirements

Requirement	Details
Android	8.0 (API 26) or higher
Bluetooth	Bluetooth LE (BLE) capable device
Permissions	See Permissions

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Building from Source

Prerequisites

• Android Studio Hedgehog or later
• JDK 17
• Android SDK with API 35

Clone and Build

git clone https://github.com/whisperbit-labs/zemzeme-android.git
cd zemzeme-android

Open in Android Studio and sync Gradle, or build from the command line:

# Debug build
./gradlew assembleDebug

# Release build (requires signing config in local.properties)
./gradlew assembleRelease

Signing (Release)

Create local.properties (not committed) and add:

KEYSTORE_FILE=/path/to/your/keystore.jks
KEYSTORE_PASSWORD=your_keystore_password
KEY_ALIAS=your_key_alias
KEY_PASSWORD=your_key_password

APK Splits

The build produces architecture-specific APKs automatically:

ABI	File suffix
arm64-v8a	...-arm64-v8a-release.apk
armeabi-v7a	...-armeabi-v7a-release.apk
x86_64	...-x86_64-release.apk

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Installation

From Release APK

1. Download the APK matching your device architecture from the Releases page
2. Enable Install from unknown sources in Android settings
3. Open the APK and install

From Source

Build the debug APK and install via ADB:

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

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Permissions

Permission	Why
BLUETOOTH_SCAN / CONNECT / ADVERTISE	BLE mesh peer discovery and communication
ACCESS_FINE_LOCATION	Required by Android for BLE scanning
ACCESS_BACKGROUND_LOCATION	Keep mesh active while app is backgrounded
INTERNET	P2P (libp2p) and Nostr transport
FOREGROUND_SERVICE	Persistent background mesh relay
RECEIVE_BOOT_COMPLETED	Auto-start mesh on device boot
POST_NOTIFICATIONS	Message notifications
CAMERA	QR code scanning for peer verification
RECORD_AUDIO	Voice notes
READ_MEDIA_IMAGES / AUDIO / VIDEO	Media sharing
REQUEST_IGNORE_BATTERY_OPTIMIZATIONS	Reliable background operation

Zemzeme does not access contacts, call logs, SMS, or any external account.

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Getting Started

1. Launch the app — no registration needed
2. Grant permissions when prompted (Bluetooth, location, notifications)
3. Pick a nickname — used only locally and in messages to peers
4. The Bluetooth group is the local BLE mesh; nearby Zemzeme users appear automatically
5. Tap + on the home screen to join a geohash channel or start a private chat
6. Scan a peer's QR code (from the verification sheet) to confirm their identity

App Lock (optional)

Go to Settings → App Lock to enable PIN + biometric protection. The lock screen appears every time the app returns to the foreground.

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Project Structure

app/src/main/java/com/roman/zemzeme/
├── crypto/            Noise protocol & symmetric encryption
├── favorites/         Peer bookmarking & persistence
├── geohash/           Location channels and geohash utilities
├── mesh/              BLE mesh engine (BluetoothMeshService, GATT managers)
├── nostr/             Nostr client, relay manager, DM handler
├── onboarding/        First-run flow, app lock setup
├── p2p/               libp2p/ICE transport, chunk assembler
├── security/          AppLockManager, PIN hashing
├── services/          QR verification, identity, background services
├── ui/                Jetpack Compose screens and sheets
│   ├── theme/         Color scheme (ElectricCyan), typography (Nunito)
│   └── media/         Image viewer, file animations
└── MainActivity.kt    Entry point, navigation, lifecycle

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Technology Stack

Component	Library / Version
UI	Jetpack Compose + Material 3
Font	Nunito (SIL OFL)
BLE	Nordic Semiconductor BLE library 2.6.1
P2P	libp2p (Go, via gomobile · golib.aar)
Nostr	Custom Kotlin client over OkHttp WebSocket
Encryption	BouncyCastle 1.70, Google Tink 1.10.0
QR Generation	ZXing 3.5.4
QR Scanning	ML Kit Barcode Scanning 17.3.0
Camera	CameraX 1.5.2
Location	Google Play Services Location 21.3.0
Biometric	AndroidX Biometric 1.1.0
Secure Storage	AndroidX Security Crypto 1.1.0-beta01
JSON	Gson 2.13.1
Coroutines	Kotlin Coroutines 1.10.2

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Contributing

Pull requests are welcome. For significant changes, please open an issue first to discuss the approach.

# Create a feature branch
git checkout -b feature/your-feature

# Make your changes, then push
git push origin feature/your-feature

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License

This project inherits the open-source license of the original bitchat project. The bundled golib.aar is compiled from go-libp2p which is licensed under the MIT License.

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Credits

• bitchat — The original project this fork is based on. Thank you to the entire bitchat team for building a solid, privacy-first foundation and for making it open source.
• libp2p — The modular peer-to-peer networking stack powering the P2P/ICE transport layer.
• Protocol Labs — Creators of libp2p, IPFS, and the broader decentralised web infrastructure that Zemzeme benefits from.
• Nostr Protocol — Simple, open protocol for decentralised social applications.