rustdeskandClaude Fable 5.1 d9f519e915 KeyExchange: signed_version, the server's signature over its version ...

The echo catches an advertisement lowered in the clear only once a tagged
frame arrives, so the initiator's first frame has already gone out under
the lower version by then. A server that signs its version instead sets
bit 255 of the ephemeral X25519 key inside the signed keys[0] and puts
sign("rdkx-ver" || key || version LE) here. RFC 7748 masks that bit, so
the box opens as before on either side, and a legacy server, whose keys
are canonical, never sets it. A client that sees the bit, or the field,
verifies before trusting the version, so the pair settles it at the
handshake rather than one frame pair later.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019aokqJuhjvB3kijXtAg5Ns

2026-09-22 13:18:45 +08:00

..

rendezvous.proto

KeyExchange: signed_version, the server's signature over its version

2026-09-22 13:18:45 +08:00