Files
bitchat/bitchatTests/Services
jackandClaude Fable 5 dbe11641ad Extend signing-key pin to persisted identity so it survives restart/eviction
The TOFU signing-key pin lived only in the in-memory peerRegistry. When
a previously seen peer was no longer in the registry (app restart, or
reconcileConnectivity pruning an offline peer), the announce trust check
saw no pinned key, treated the announce as first contact, and
persistIdentity overwrote the cached signing key/nickname — so an
attacker could replay a victim's noiseKey/peerID with their own signing
key and bypass the spoofing protection for returning/offline peers.

Fixes:

- BLEAnnounceHandler now falls back to the persisted cryptographic
  identity (via a new persistedSigningPublicKey environment closure)
  when the registry has no signing key for the peer, so the pin remains
  effective across registry eviction and app restarts. BLEService wires
  it to SecureIdentityStateManager.getCryptoIdentitiesByPeerIDPrefix,
  the same synchronous identity-manager read already used on the packet
  path by signedSenderDisplayName.
- SecureIdentityStateManager.upsertCryptographicIdentity refuses to
  replace a persisted signing key with a different one (security-logged,
  nickname update included in the refusal), mirroring the registry
  policy. First-writer-wins persistence also removes any race where a
  concurrent announce could poison the stored identity.
- CryptographicIdentity entries (incl. the signing-key pin) are now part
  of the encrypted IdentityCache, so they actually persist across app
  restarts; previously they were in-memory only. Old caches without the
  new field still decode (decodeIfPresent), and clearAllIdentityData /
  panic wipe clears the pins as before.

Legitimate re-keying: presenting a different signing key for the same
noise key is exactly the attack being blocked, so refusal is correct
and permanent until the peer adopts a new noise identity (new peerID)
or the user explicitly clears identity data. Repeated rejected announces
follow the existing unverified-announce path (log + ignore); no retry
loops or crashes.

Tests: handler-level persisted-pin mismatch/match/precedence cases, an
end-to-end restart+eviction test with real Ed25519 keys and a real
SecureIdentityStateManager showing the attacker replay is rejected and
the persisted identity is untouched while the victim re-announce is
accepted, and identity-manager tests for the pinned-key refusal and the
keychain round-trip of the pin.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-01 23:55:40 +02:00
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