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* Sign public broadcasts; verify relayed messages via persisted signing keys; keep scheduled relays in sparse graphs and speed their jitter; persist announce signing key for offline auth; add short backoff after disconnect errors to reduce reconnect thrash * Add connected vs reachable model: retain peers after link drop, expire after reachability window; expose all peers in snapshots; compute isReachable in UI; add meshReachable state and sorting; avoid removing peers on link events; notify UI on stale removals * ContentView: handle new .meshReachable connection state in header icon switch (exhaustive switch fix) * Logs: tag relayed announces as 'Reachable via mesh' and annotate public message logs with (direct|mesh) path for easier field analysis * Fix syntax error: remove stray else/log inserted into writeOrEnqueue; keep logs clean * UI: use 'point.3.connected.trianglepath.dotted' for mesh-reachable; change people count to include connected+reachable (exclude Nostr-only) * UI: switch to 'point.3.filled.connected.trianglepath.dotted' for mesh-reachable icons in list and header * Reachability: reduce retention to 21s for all peers (verified and unverified) to minimize stale presence * mesh DMs/acks: route to reachable peers; queue READ/DELIVERED until handshake; add Transport.isPeerReachable; UI: hide offline non-mutuals; DM header: better name fallback + show transport + encryption icons; fix NostrTransport conformance * Verification sheet: compute encryption status and fingerprint using short mesh ID mapping (fix 'not encrypted/handshake' for DMs with stable key) * Announce cadence: faster discovery (4s), sparse 15±4s, dense 30±8s; initial 0.6s; post-subscribe 50ms; min-force 150ms; maintenance 5s; proactive announces on handshake + recent-traffic nudge * Relay: increase broadcast TTL cap in sparse graphs to 6; tighten jitter for handshake (10–35ms) and directed (20–60ms) relays * Range/robustness: store-and-forward for directed packets (15s) with flush on new links + periodic; announces: no subset + afterglow re-announce on first-seen; adaptive scanning: force ON when <=2 neighbors or recent traffic * Fix warnings: remove unused msgID and unused mutable var in directed spool flush * Announces: TTL 7 (sparse only) via RelayController; no fanout subset for announces; neighbor-change rebroadcast of last 2–3 announces. Fragments: faster pacing (5ms global, 4ms directed). * Peer list: real-time icon updates by publishing snapshots on connectivity checks; add unread message indicator (envelope) next to peers with unread DMs * UI: unread envelope uses orange; hasUnreadMessages checks Nostr conv key for peers with known Nostr pubkeys (geohash DM consistency) * Logs/robustness: debounce disconnect notifications (1.5s), debounce 'reconnected' logs (2s), add weak-link cooldown after timeouts on very weak RSSI (<= -90) * Peer icons: faster, accurate reachability\n\n- Run connectivity checks every maintenance tick (5s)\n- Publish peer snapshots on central unsubscribe for instant UI refresh\n- Lower inactivity timeout to 8s and disconnect debounce to 0.9s\n- Gate reachability on mesh-attached (>=1 direct link); no links => no reachable peers\n- Keep 21s retention for verified/unverified, but only when attached to mesh\n\nImproves list responsiveness when walking out of range and prevents stale 'reachable' states when isolated. --------- Co-authored-by: jack <jackjackbits@users.noreply.github.com>
bitchat
A decentralized peer-to-peer messaging app that works over Bluetooth mesh networks. No internet required, no servers, no phone numbers. It's the side-groupchat.
Warning
Private messages have not received external security review and may contain vulnerabilities. Do not use for sensitive use cases, and do not rely on its security until it has been reviewed. Now uses the Noise Protocol for identity and encryption. Public local chat (the main feature) has no security concerns.
License
This project is released into the public domain. See the LICENSE file for details.
Features
- Decentralized Mesh Network: Automatic peer discovery and multi-hop message relay over Bluetooth LE
- Privacy First: No accounts, no phone numbers, no persistent identifiers
- Private Message End-to-End Encryption: Noise Protocol
- IRC-Style Commands: Familiar
/slap,/msg,/whostyle interface - Universal App: Native support for iOS and macOS
- Emergency Wipe: Triple-tap to instantly clear all data
- Performance Optimizations: LZ4 message compression, adaptive battery modes, and optimized networking
Technical Architecture
Binary Protocol
bitchat uses an efficient binary protocol optimized for Bluetooth LE:
- Compact packet format with 1-byte type field
- TTL-based message routing (max 7 hops)
- Automatic fragmentation for large messages
- Message deduplication via unique IDs
Mesh Networking
- Each device acts as both client and peripheral
- Automatic peer discovery and connection management
- Adaptive duty cycling for battery optimization
For detailed protocol documentation, see the Technical Whitepaper.
Setup
Option 1: Using XcodeGen (Recommended)
-
Install XcodeGen if you haven't already:
brew install xcodegen -
Generate the Xcode project:
cd bitchat xcodegen generate -
Open the generated project:
open bitchat.xcodeproj
Option 2: Using Swift Package Manager
-
Open the project in Xcode:
cd bitchat open Package.swift -
Select your target device and run
Option 3: Manual Xcode Project
- Open Xcode and create a new iOS/macOS App
- Copy all Swift files from the
bitchatdirectory into your project - Update Info.plist with Bluetooth permissions
- Set deployment target to iOS 16.0 / macOS 13.0
Option 4: just
Want to try this on macos: just run will set it up and run from source.
Run just clean afterwards to restore things to original state for mobile app building and development.