a74fa1066e
Review found the patch fixed the case that matters least and could hurt the peer it protects. Both are addressed here. **The connected peer kept its seal.** `verifiedBadge` already carried `!peer.isConnected`, so gating it on the rename was dead for a connected peer. For that peer the seal comes from somewhere else entirely: `EncryptionStatus.noiseVerified.icon` is the same `checkmark.seal.fill` glyph, rendered straight from `peer.encryptionStatus.icon` in `MeshPeerList` and again in the DM header in `ContentSheetViews`. Neither was gated, so a verified key that renamed while holding a Noise session — the live impersonation — kept a filled seal beside the new name. The binding now applies at `ChatPeerIdentityCoordinator.getEncryptionStatus`, which both of those read through, demoting `.noiseVerified` to `.noiseSecured`: the session really is encrypted, only the claim about *who* is withdrawn. Nothing branches on `.noiseVerified` beyond the glyph — every behavioural site already treats it and `.noiseSecured` alike — so this changes what is drawn and nothing else. The demotion is computed on read rather than stored, because the cached status is invalidated by verification and session changes but never by a rename; a demotion written into the cache would be stale and sticky. It also has to run on the cache-hit path, which is the common one — the new coordinator test caught that being missed. **The comparison could suppress the victim.** `peer.nickname` is already collision-resolved: `BLEPeerRegistry.transportSnapshots` runs names through `PeerDisplayNameResolver`, which appends `#` plus four hex of the peerID to CONNECTED peers whose nicknames collide. That is precisely the attack — two connected peers both claiming "medic" — so the real medic's `peer.nickname` becomes "medic#c3d4", no longer equals the pinned "medic", and the impersonated peer loses its seal exactly when it matters. So the check no longer takes a name at all. It compares the pinned baseline against the peer's own announced nickname, both in NFC via `normalizedNickname` to match how nicknames are compared everywhere else. That removes three failure modes at once: the collision suffix, the `splitSuffix()` overload that also stripped every `@` from a legal nickname, and the divergence between a message row's historical sender name and the live one. A local petname is handled centrally in the same place, since it outranks the claimed nickname wherever it is displayed. Tests: two coordinator cases for the demotion, including that it is not written into the cache and that it leaves secured and handshaking states alone; a regression guard asserting `PeerDisplayNameResolver` really does decorate and that the binding ignores it; petname and NFC cases. 15 in the binding suite, 10 in the coordinator suite.
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.
Getting a copy you can trust
Install from the App Store, or build from source you have verified. A compiled build from anywhere else cannot be verified — see Verifying bitchat for how to check source against the per-release hash manifest, and for what to do if that is the only build you can get.
This matters more than it usually would: this repository has been the target of takedown demands, and when a repository or releases page disappears, mirrors appear that nobody can check.
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 servers. Note that the mesh does use a persistent per-device identifier derived from your identity key — see the whitepaper on identity and metadata for what a nearby radio can observe
- Private Message End-to-End Encryption: Noise Protocol for mesh, BitChat private envelopes for Nostr fallback
- 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 for live sessions (store-and-forward mail is sealed without it — see the whitepaper)
- 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
- 440+ Relay Network: Distributed across the globe for reliability
- BitChat Private Envelopes: App-specific encrypted private messages over Nostr relays
- Ephemeral Keys: Fresh cryptographic identity per geohash area
BitChat's private-envelope format is proprietary and is not NIP-17,
NIP-44, or NIP-59 compatible. It uses Nostr as a relay transport but only
interoperates with BitChat clients: private payloads travel inside kind-1059
events whose v2:-prefixed content is a BitChat-specific XChaCha20-Poly1305
construction, not NIP-44 encryption.
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
- BitChat's app-specific private-envelope encryption
- 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
open bitchat.xcodeproj
For a signed device build, create your ignored local configuration and replace the example team ID with your Apple Developer Team ID:
cp Configs/Local.xcconfig.example Configs/Local.xcconfig
Local.xcconfig.example derives unique app and App Group identifiers from that
team ID. The entitlement files already reference $(APP_GROUP_ID), so tracked
project or entitlement files do not need to be edited.
Useful command-line checks from the repository root:
# macOS Debug build without signing
xcodebuild -project bitchat.xcodeproj -scheme "bitchat (macOS)" \
-configuration Debug CODE_SIGNING_ALLOWED=NO build
# Full SwiftPM test suite
swift test
# iOS simulator tests
xcodebuild -project bitchat.xcodeproj -scheme "bitchat (iOS)" \
-sdk iphonesimulator \
-destination 'platform=iOS Simulator,name=iPhone 17' test
If iPhone 17 is unavailable, choose an installed simulator from:
xcodebuild -showdestinations -project bitchat.xcodeproj -scheme "bitchat (iOS)"
Option 2: Using just
brew install just
just check
just run
just build and just run use the current bitchat (macOS) scheme and keep
Xcode output in the ignored .DerivedData/ directory. They never patch source,
project, configuration, or entitlement files.
just clean removes only .DerivedData/ and .build/. It does not invoke Git
or restore tracked files, so uncommitted work is preserved. just test runs the
SwiftPM suite and just test-ios runs the iPhone 17 simulator suite.
Localization
- App localizations live in
bitchat/Localizable.xcstrings. - Share extension strings are separate in
bitchatShareExtension/Localization/Localizable.xcstrings. - 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.