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* Add capability bits to announce TLV Announces now carry an optional capabilities TLV (0x05): a little-endian bitfield with named bits for upcoming features (prekeys, wifiBulk, gateway, groups, board, vouch, meshDiagnostics). Old clients skip the unknown TLV; peers without it decode as nil so features can distinguish "legacy peer" from "advertises nothing". PeerCapabilities lives in BitFoundation with a minimal-length encoding that preserves unknown bits for forward compatibility. Peer capabilities are stored in the BLE peer registry on verified announce and exposed via BLEService.peerCapabilities(_:). The local advertisement set is empty until each feature ships its bit. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> * Transitive verification: vouch for verified peers over Noise When a Noise session establishes with a peer I verified and that peer advertises the .vouch capability, send signed attestations (up to 16, most recently verified first, at most once per peer per 24h) for the OTHER fingerprints I verified. Receivers accept vouches only from senders they verified themselves, verify the Ed25519 signature against the sender's announce-bound signing key, and surface the result as a new derived trust tier: vouched (unfilled seal) between casual and trusted. Protocol: - NoisePayloadType.vouch = 0x12 carries a batch of TLV attestations: voucheeFingerprint (32B), voucheeSigningKey (32B), timestamp (uint64 ms BE), Ed25519 signature over "bitchat-vouch-v1" | fingerprint | signingKey | timestamp. The voucher is implicit in the authenticated session. - PeerCapabilities.localSupported now advertises .vouch. Storage (SecureIdentityStateManager / IdentityCache): - vouches keyed by vouchee, capped at 8 vouchers each; validity is recomputed on read (voucher still verified-by-me, < 30 days old), so unverifying a voucher retires their vouches without cascade deletes. - New IdentityCache fields are Optional so pre-existing encrypted caches decode cleanly; TrustLevel.vouched is inserted mid-ladder but raw values are strings, so persisted values are unaffected (and vouched itself is never persisted). - Panic wipe clears vouch state with the rest of the identity cache. UI: unfilled checkmark.seal badge in the mesh peer list (filled seal stays exclusive to verified) and a "vouched for by N people you verified" section with voucher names in FingerprintView; VoiceOver labels and xcstrings entries included. Tests: attestation encode/decode + signature (forged/tampered/expired), accept-policy gates, batch cap, trust-level derivation incl. voucher invalidation, persistence compat, and coordinator exchange/accept policies. Full macOS suite: 1088 tests passing. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> * Fix CI deadlock in vouch tests and live-refresh the fingerprint sheet on vouch acceptance Two fixes for PR #1380 review findings: 1. CI "Run Swift Tests (app)" hang (exit 137): the new SecureIdentityStateManagerVouchTests suite was nonisolated, so Swift Testing ran its tests in parallel on the Swift Concurrency cooperative pool. Each test enqueues a queue.async(.barrier) write (setVerified) and immediately blocks in queue.sync / queue.sync(.barrier) (recordVouch / effectiveTrustLevel). On CI's few-core runners every cooperative-pool thread ended up parked behind a pending barrier that never got a dispatch worker, deadlocking the whole test process until the watchdog SIGKILLed it. The suite is now @MainActor, matching the production isolation of the vouch API (ChatVouchCoordinator is @MainActor) and keeping blocking syncs off the cooperative pool. 2. Codex P2: an open fingerprint sheet did not refresh its vouched badge when a vouch batch was accepted - VerificationModel.bind() never observed the trust-change signal. It now subscribes to the "peerStatusUpdated" notification that ChatVouchCoordinator.notifyPeerTrustChanged() posts (same source PeerListModel uses) and forwards it to objectWillChange. Added a regression test that pins VerificationModel's own subscription (verified to fail without the fix). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> * Skip media-wipe detached tasks under tests (shared-filesystem race) panicClearAllData and clearCurrentPublicTimeline delete the real ~/Library/Application Support/files tree in detached utility-priority tasks. The SPM test process shares that tree and ChatViewModelTests invoke both methods, so under parallel scheduling the wipe lands at a nondeterministic time — deleting media a concurrently running test just wrote (and the developer's real app data with it). Guard both with the existing TestEnvironment.isRunningTests pattern, mirroring the same fix on feat/mesh-diagnostics (#1377). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> * Port vouch capability-race fix to feat/vouching (ports b8adcbe9) Ports the on-device-confirmed fix from the integration test branch (commit b8adcbe9) onto feat/vouching so PR #1380 is actually correct. On-device testing confirmed the transitive vouch propagated once the send was triggered on verify / announce arrival rather than auth alone. Vouch attestations only ever sent from peerAuthenticated, gated on the peer's .vouch capability. That capability arrives via the peer's announce, processed independently of the Noise handshake, so at auth time the set was usually empty -> gate failed -> vouch silently skipped and never retried. - Refactor the send path into a reusable attemptVouch(to:fingerprint:now:). - Trigger on peer-list updates (peersUpdated): fired after every verified announce, so the batch goes out once the .vouch bit actually arrives. - Trigger on local verification (vouchToConnectedVerifiedPeers): verifying a peer runs a vouch pass over connected verified peers, covering the verify-while-connected case and propagating the new identity onward. - Relax the capability gate: treat an empty/unknown set as eligible (the Noise 0x12 payload is ignored by non-supporting peers); only skip when a non-empty set explicitly lacks .vouch. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> --------- Co-authored-by: jack <jackjackbits@users.noreply.github.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
bitchat
A decentralized peer-to-peer messaging app with dual transport architecture: local Bluetooth mesh networks for offline communication and internet-based Nostr protocol for global reach. No accounts, no phone numbers, no central servers. It's the side-groupchat.
License
This project is released into the public domain. See the LICENSE file for details.
Features
- Dual Transport Architecture: Bluetooth mesh for offline + Nostr protocol for internet-based messaging
- Location-Based Channels: Geographic chat rooms using geohash coordinates over global Nostr relays
- Intelligent Message Routing: Automatically chooses best transport (Bluetooth → Nostr fallback)
- 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 for mesh, NIP-17 for Nostr
- 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
BitChat uses a hybrid messaging architecture with two complementary transport layers:
Bluetooth Mesh Network (Offline)
- Local Communication: Direct peer-to-peer within Bluetooth range
- Multi-hop Relay: Messages route through nearby devices (max 7 hops)
- No Internet Required: Works completely offline in disaster scenarios
- Noise Protocol Encryption: End-to-end encryption with forward secrecy
- Binary Protocol: Compact packet format optimized for Bluetooth LE constraints
- Automatic Discovery: Peer discovery and connection management
- Adaptive Power: Battery-optimized duty cycling
Nostr Protocol (Internet)
- Global Reach: Connect with users worldwide via internet relays
- Location Channels: Geographic chat rooms using geohash coordinates
- 290+ Relay Network: Distributed across the globe for reliability
- NIP-17 Encryption: Gift-wrapped private messages for internet privacy
- Ephemeral Keys: Fresh cryptographic identity per geohash area
Channel Types
mesh #bluetooth
- Transport: Bluetooth Low Energy mesh network
- Scope: Local devices within multi-hop range
- Internet: Not required
- Use Case: Offline communication, protests, disasters, remote areas
Location Channels (block #dr5rsj7, neighborhood #dr5rs, country #dr)
- Transport: Nostr protocol over internet
- Scope: Geographic areas defined by geohash precision
block(7 chars): City block levelneighborhood(6 chars): District/neighborhoodcity(5 chars): City levelprovince(4 chars): State/provinceregion(2 chars): Country/large region
- Internet: Required (connects to Nostr relays)
- Use Case: Location-based community chat, local events, regional discussions
Direct Message Routing
Private messages use intelligent transport selection:
-
Bluetooth First (preferred when available)
- Direct connection with established Noise session
- Fastest and most private option
-
Nostr Fallback (when Bluetooth unavailable)
- Uses recipient's Nostr public key
- NIP-17 gift-wrapping for privacy
- Routes through global relay network
-
Smart Queuing (when neither available)
- Messages queued until transport becomes available
- Automatic delivery when connection established
For detailed protocol documentation, see the Technical Whitepaper.
Setup
Option 1: Using Xcode
cd bitchat
open bitchat.xcodeproj
To run on a device there're a few steps to prepare the code:
- Clone the local configs:
cp Configs/Local.xcconfig.example Configs/Local.xcconfig - Add your Developer Team ID into the newly created
Configs/Local.xcconfig- Bundle ID would be set to
chat.bitchat.<team_id>(unless you set to something else)
- Bundle ID would be set to
- Entitlements need to be updated manually (TODO: Automate):
- Search and replace
group.chat.bitchatwithgroup.<your_bundle_id>(e.g.group.chat.bitchat.ABC123)
- Search and replace
Option 2: Using just
brew install 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.
Localization
- Base app resources live under
bitchat/Localization/Base.lproj/. Add new copy toLocalizable.stringsand plural rules toLocalizable.stringsdict. - Share extension strings are separate in
bitchatShareExtension/Localization/Base.lproj/Localizable.strings. - Prefer keys that describe intent (
app_info.features.offline.title) and reuse existing ones where possible. - Run
xcodebuild -project bitchat.xcodeproj -scheme "bitchat (macOS)" -configuration Debug CODE_SIGNING_ALLOWED=NO buildto compile-check any localization updates.