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jackandClaude Fable 5
ee148a018b
Courier envelopes were sealed with one-way Noise X to the recipient's long-lived static key, so a later compromise of that key exposed every envelope captured in transit. This adds one-time prekey bundles: - PrekeyBundle (MessageType 0x24): 8 one-time Curve25519 public prekeys bound to the owner's Noise static key by an Ed25519 signature over "bitchat-prekey-bundle-v1" canonical bytes; gossiped mesh-wide on its own 60s sync round (SyncTypeFlags bit 9, 200-peer cap, 24h freshness) and verified against the announce-bound signing key before caching. - Sealed envelope v2: Noise X where the responder static is the one-time prekey, prologue "bitchat-prekey-v1" || prekeyID. Sender identity rides encrypted inside and is authenticated exactly like v1 (blocked-sender check included). CourierEnvelope gains an optional prekeyID TLV that v1 decoders skip as unknown. - Local prekeys live in the Keychain; consumed privates survive a 48h grace window for spray-and-wait redeliveries, then are deleted (the forward-secrecy clock starts at deletion). The batch tops back up and re-gossips when unconsumed count drops below 3, and everything is wiped in panic mode. - Routing: courier sealing picks a cached verified bundle when one exists (one prekey per message, reused across deposit retries), with the advertised .prekeys capability as a veto for on-mesh peers, and falls back to static sealing otherwise. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Test Harness Guide
This test suite uses an in-memory networking harness to make end-to-end and integration tests deterministic, fast, and race-free without touching production code.
In-Memory Bus
- File:
bitchatTests/Mocks/MockBLEService.swift - Registry/Adjacency: Global
registrymapspeerIDto aMockBLEServiceinstance;adjacencyrecords simulated links between peers. - Setup: Call
MockBLEService.resetTestBus()insetUp()to clear state between tests. - Topology: Use
simulateConnectedPeer(_:)andsimulateDisconnectedPeer(_:)to add/remove links.connectFullMesh()helpers in tests build larger topologies. - Handlers: Tests can observe data via
messageDeliveryHandler(decodedBitchatMessage) andpacketDeliveryHandler(rawBitchatPacket). - De‑duplication: A thread-safe
seenMessageIDsprevents duplicate deliveries during flooding/relays.
Broadcast Flooding
- Flag:
MockBLEService.autoFloodEnabled - Intent: When
true, public broadcasts propagate across the entire connected component (ignores TTL for reach) while still de‑duping to prevent loops. - Usage: Enabled in Integration tests (
setUp) to simulate large-network broadcast; disabled in E2E tests to keep routing explicit and verify TTL behavior (seePublicChatE2ETests.testZeroTTLNotRelayed).
Rehandshake Flow (Noise)
- Why: The legacy NACK recovery path was removed; recovery now relies on Noise session rehandshake after decrypt failure or desync.
- Manager:
NoiseSessionManagermanages per-peer sessions. - Pattern: On decrypt failure, proactively clear the local session and re-initiate a handshake. The peer accepts and replaces their session.
- Test:
IntegrationTests.testRehandshakeAfterDecryptionFailure- Corrupts ciphertext to induce a decrypt error.
- Calls
removeSession(for:)on the initiator’s manager beforeinitiateHandshake(with:)to avoidalreadyEstablished. - Verifies encrypt/decrypt succeeds post-rehandshake.
Tips
- Determinism: Add small async delays only where handler installation/topology changes could race the first send.
- Scoping: Keep
autoFloodEnabledtoggled only within Integration tests; always reset intearDown()to avoid cross-test contamination. - Direct vs Relay: Private messages target a specific peer when adjacent; otherwise they are surfaced to neighbors for relay and, if known, also delivered to the target.
Quick Start
- Create nodes and connect them:
let svc = MockBLEService(); svc.myPeerID = "PEER1"svc.simulateConnectedPeer("PEER2")
- Observe messages:
svc.messageDeliveryHandler = { msg in /* asserts */ }
- Enable broadcast flooding for Integration suites only:
MockBLEService.autoFloodEnabled = true