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c8479c15e3
* PTT hardening: burst-ID collision hijack + live-capture quota bypass Fix C — burst-ID collision hijack: inbound live-voice assemblies and the finished-burst registry were keyed by the sender-chosen burst ID alone, so an attacker who observed a public burst ID could race a START and capture the real talker's frames (packets from the true sender were dropped as "collisions"). Assemblies now key on (peerID, scope, burstID): a colliding START from another peer opens its own capped assembly and can never divert the victim's frames; finalized-note absorption matches on the same triple, preserving the sender/scope binding. Live capture files also gain the peer ID in their name so colliding bursts land on distinct paths (still rejected by burstID(fromVoiceFileName:), so live names remain unabsorbable). Fix B — live-burst files bypassed the incoming-media quota: progressive voice_live_*.aac captures were written via raw FileHandle without ever touching BLEIncomingFileStore.enforceQuota, growing disk unbounded outside the 100 MB LRU accounting. The coordinator now takes an injected BLEIncomingFileStore, reserves pttMaxBurstBytes before opening a capture, and sweeps orphaned voice_live_* partials from previous sessions at startup. enforceQuota gains an `excluding:` set so in-flight partials are never LRU-evicted mid-stream; existing callers are unaffected. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> * Review fixes: pattern-guard live captures in quota, scope in capture names Quota-eviction gap: BLEFileTransferHandler enforces the quota for every finalized arrival via enforceQuota(reservingBytes:) with no exclusion set, so a file landing at quota could LRU-evict an in-flight live capture — unlinking the inode under the coordinator's open FileHandle and leaving a dead bubble. Protection is now layer-independent: enforceQuota itself skips voice_live_* names (they still count toward usage), and the excluding: parameter is gone since the pattern guard covers its only caller. Orphaned partials are still reclaimed by the coordinator's startup sweep, which the quota deliberately never touches. Same-peer cross-scope truncation: makeIncomingURL omitted the scope, so one peer running a DM burst and a public burst with the same burst ID mapped both assemblies onto one path — and FileManager.createFile truncates, so each START corrupted the other capture. Names now mirror the assembly key: voice_live_<burstHex>_<peerID>_<dm|mesh>.aac. The sweep and quota guard match on the voice_live_ prefix and burstID(fromVoiceFileName:) still rejects every live name, so live captures remain unabsorbable; sameBurstIDCoexistsAcrossScopes now asserts both files survive with intact contents. Nits: the coordinator's file operations route through the store's injectable FileManager instead of FileManager.default, and the TestEnvironment.isRunningTests branch in init is replaced by a sweepsOnInit parameter (tests sharing the real application-support directory pass false for hermeticity). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> * Promote kept live captures off the voice_live_ name at finalize Codex P1 follow-up: when a burst finalizes with frames but its .m4a note never arrives, the voice_live_*.aac capture stays behind as the bubble's replayable audio — yet the startup sweep deletes every voice_live_* file and the quota guard skips them forever, so a kept fallback was both quota-immune for the rest of the session and doomed at the next launch. finalize now promotes the capture to a plain voice_ name (same suffix) and republishes the row pointing at it; the finished-burst registry tracks the promoted URL so a late note still absorbs and deletes it. voice_live_ is thereby scoped to genuinely in-flight captures: the sweep never touches a referenced fallback, and promoted files age out of the quota like any finalized media. If the move fails the live name is kept — exactly the pre-promotion behavior. Premise correction, verified while tracing the reference model: chat rows are NOT persisted across restarts (ConversationStore is in-memory; the gossip archive replays MessageType.message packets only), so today's sweep never orphaned a persisted row — the fix removes the in-session quota immunity and makes the invariant hold if row persistence ever lands. Crash case stays deliberate and documented: a mid-burst partial from a dead process is swept because no surviving row can reference it. Tests: finalize-as-fallback promotes the file, repoints the row, and survives a later coordinator's startup sweep; promoted fallbacks are LRU-evictable by the quota; the sweep still removes true orphans while sparing promoted names; existing burst tests updated for the promoted paths. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> --------- Co-authored-by: jack <jackjackbits@users.noreply.github.com> Co-authored-by: Claude Opus 4.8 <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.