Upgrades the signaling layer from static X25519 (2.0) to per-session
ephemeral X25519 (2.1). Recorded signaling traffic cannot be decrypted
even if long-term Ed25519 keys later leak, because esk is zeroed on
session close.
Protocol:
- Each peer generates a fresh X25519 keypair (esk/epk) per session.
- Peers exchange signed `ekey` messages sealed under static keys before
the offer/answer. Offer/answer/candidate payloads are then sealed with
ephemeral keys (crypto_box(·, peer_epk, my_esk)).
- ekey sig binds both peer IDs and the epk to prevent replay to third parties.
- Offerer waits up to 2 s for the peer's ekey; if none arrives it falls back
to YAW/2.0 static-key sealing and logs "2.0 fallback offer".
- 2.0 peers silently ignore the unknown `ekey` kind — full interop preserved.
Implementation:
- crypto.go: add EphemeralKey.PublicRaw/PrivateRaw/Wipe helpers.
- proto.go: add SigEkey kind; EPK/V/EkeySig fields on SignalingPayload.
- anchor/client.go: replace flat pcs map with peerSession struct tracking
ephemeral keys, peerEPK, and fs flag; openBoxAuto tries ephemeral then
static; sealAndSend chooses seal based on session state.
- test-network.sh: pipe daemon stderr through tee to daemon.log; add
YAW/2.1 FS verification section.
- test-tui.sh: same daemon.log capture.
- README.md: document 2.1 forward secrecy, file transfer IPC, updated roadmap.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
274ff423f6