mirror of
https://github.com/permissionlesstech/bitchat.git
synced 2026-07-25 08:05:20 +00:00
Residual gap after the rotation-heal containment (#1401): "verified direct" announces prove the signature but not directness — TTL is unsigned — so a malicious connected peer can replay a victim's fresh announce with its TTL restored. When the victim has no live link, the replayer's link rebinds to the victim's ID and reads as "connected", and MessageRouter's connected fast-path then trusts it outright: every DM stalls on a Noise handshake the replayer can never complete and is silently lost while showing "sent". Router-level trust gate (no wire change): - Transport gains canDeliverSecurely(to:) — BLE answers with an established Noise session; Nostr keeps its prompt-delivery predicate; the protocol default forwards to canDeliverPromptly for transports without a forgeable link layer. - MessageRouter.sendPrivate only trusts a connected link outright when it can deliver securely; otherwise it still sends (kicking the handshake on a genuine link) but retains a copy and hands a sealed copy to couriers, like the reachable path. flushOutbox gets the same gate so a flush over an insecure link resends instead of dropping the retained copy. Presence hardening (defense in depth): a "direct" announce arriving on a link already bound to a different peer no longer shortcuts the claimed peer into "connected" — only real link state does. Genuine first-contact and direct announces are unaffected; only the ambiguous heal path loses the forgeable shortcut. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>