bitchat

A secure, end-to-end encrypted Bluetooth mesh chat application with an IRC-style interface.

License

This project is released into the public domain. See the LICENSE file for details.

Features

• End-to-end encryption using Curve25519 and AES-GCM
• Bluetooth mesh networking with automatic peer discovery
• Message relay capability (TTL-based flooding)
• IRC-style terminal interface
• Persistent nickname storage
• Universal app (iOS and macOS)
• No internet connection required

Setup

Option 1: Using XcodeGen (Recommended)

1. Install XcodeGen if you haven't already:

   brew install xcodegen
   

2. Generate the Xcode project:

   cd bitchat
   xcodegen generate
   

3. Open the generated project:

   open bitchat.xcodeproj
   

Option 2: Using Swift Package Manager

1. Open the project in Xcode:

   cd bitchat
   open Package.swift
   

2. Select your target device and run

Option 3: Manual Xcode Project

1. Open Xcode and create a new iOS/macOS App
2. Copy all Swift files from the bitchat directory into your project
3. Update Info.plist with Bluetooth permissions
4. Set deployment target to iOS 16.0 / macOS 13.0

Usage

1. Launch the app on multiple devices
2. Choose or modify your nickname
3. The app will automatically discover nearby peers
4. Start chatting! Messages are relayed through the mesh network

Security

• All messages are end-to-end encrypted
• Public key exchange happens automatically on connection
• Messages are signed to prevent tampering
• TTL prevents infinite message loops

Protocol

The bitchat protocol uses JSON-encoded packets with the following structure:

• Packet versioning for future compatibility
• Message types: handshake, message, ack, relay, announce, keyExchange
• TTL-based flooding for mesh relay
• Signature verification for authenticity

Building for Production

1. Set your development team in project settings
2. Configure code signing
3. Archive and distribute through App Store or TestFlight

Android Compatibility

The protocol is designed to be platform-agnostic. An Android client can be built using:

• Bluetooth LE APIs
• Same packet structure and encryption
• Compatible service/characteristic UUIDs