lockbitchat
6152a77b51
A security review of the transport and verification layers. Every item is a fix
to how untrusted peer input is handled; no features changed.
- SAS verification could be bypassed. `verification_both_confirmed` is an
unauthenticated frame on a channel that is not yet trusted, but it was taken as
proof that both sides had compared their codes — so a peer who completed the
signalling exchange could send it right after the data channel opened and drive
the other side to a "verified" session while the user never looked at the code.
It is now only an acknowledgement: refused unless this side already confirmed
locally, and _setVerifiedStatus() independently rejects any SAS-based
transition without a local confirmation. Holding ECDH-derived keys was never
proof of identity — a MITM has those too.
- Unauthenticated frames could be injected into the chat. A bare
{type:"message"} frame, a raw non-JSON frame and a binary frame were each
decoded and rendered, bypassing decryption, the HMAC check and the verification
gate; the injected text was indistinguishable from a genuine message. Chat
content now reaches the UI only through the authenticated enhanced_message
path.
- A peer could supply the verification code. `sas_code` announcements were
adopted verbatim when no local SAS had been derived yet. They may now only
corroborate the locally derived code.
- Anti-replay never ran. The sequence-number and AAD validators were defined on
SecureKeyStorage instead of the connection manager, so every call site failed
with a TypeError and the sliding replay window was dead code. Moved onto the
manager, wired into the live chat path, and a missing or non-numeric sequence
number now fails closed instead of sailing through the range checks.
- File transfers are gated on verification in both directions. Control frames are
written straight to the data channel by the transfer system; sending was
already gated, receiving now is too.
- Tighter CSP: connect-src and img-src no longer allow arbitrary https: hosts
(nothing in the app talks to a third party), plus base-uri 'none'.
- The SAS is no longer written to logs, and is compared in constant time on every
path. Fixed SecureMasterKeyManager.isUnlocked() testing a field renamed long
ago, so it never actually gated anything.
- Fixed the header showing "Secure undefined%": getRealSecurityLevel() became
reachable for the first time by the move above and returned only per-feature
booleans, while the header renders `level` and `score` directly. It now runs
the same verified scoring as every other consumer.
Adds regression tests for the verification gate, inbound frame authentication and
the security-level shape.