To ensure two peers agree on a key, we need asymmetry. one peer is
the controller ("initiator") the other is the "responder".
Otherwise imagine two offers in parallel driving two answers at the same time
A B
| <----B-OFFER----- |
| -----A-OFFER----> |
| |
| |
---------------------------------
|****** ICE + WG Handshake ****** |
---------------------------------
| |
| <----B-ANSWER---- |
| -----A-ANSWER---> |
PSK is derived on receive of offer, so A and B derive different PSKs.
When WG handshake takes place it picks misaligned PSKs.
So we impair the two nodes and only the offer of one of the two (the controller/initiator)
carries the KEM material.
This means that if the responder OFFER/ANSWER comes first, when the controller/initiator's one
completes (and the genuine PSK is shared between A and B, we need to force a new WG handshake with
the proper keys.
- RecoversViaResignalAfterDataPathBreak: a data-path rotation that can no longer
converge raises OnRekeyFailed, and re-bootstrapping over signalling resyncs both
peers on a fresh PSK even while the data path stays broken.
- ConcurrentRekeysNoRace: hammers the single-lock state machine with concurrent
rotation clocks from many goroutines (run with -race) and asserts no split-brain
via a final deterministic bootstrap.
Strict mode (NB_PQ_MLKEM_STRICT, default off) closes the initial PQ-vulnerable
window (NET-1408): when enabled, conn.presharedKey programs a per-conn random
sentinel PSK until the ML-KEM exchange derives the real one, so no session can form
on a non-PQ key (the real PSK is pushed via SetPresharedKey once it converges).
Default stays opportunistic.
Also surface PQ status: the peer 'Quantum resistance' flag (RosenpassEnabled) is now
true when an ML-KEM PSK has been derived for the peer, not only for Rosenpass.
Replace the raw SHA-256 concat combiner with HKDF-SHA256 (crypto/hkdf, Go 1.24):
IKM = ML-KEM_ss || X25519_ss (draft-ietf-tls-ecdhe-mlkem order), salt = the
domain-separation label, info = full transcript (offer || answer) || canonicalised
peer identities. Keeps the transcript + identity binding while using a proper KDF.
- Add a trace slog level (NB_PQ_MLKEM_LOG_LEVEL=trace) and move the verbose
per-exchange lifecycle logs (offer/answer/PSK/ack/rotation) to it, so debug
stays quiet and troubleshooting is opt-in.
- Stop logging the raw preshared key; drop the temporary pqkem-dbg OnRemoteOffer/
OnRemoteAnswer probes.
- Demote the per-handshake conn log to trace.
We clock the next Offer initiation to the OnDataPathRekeyed, so we have 2 minutes
ahead of us to do our attempts and stuff before to give up.
On failure, we will know because we will not receive a new answer.. but more importantly
the wg handshake will fail :D
Define OnDataPathRekeyed event to transition from control plane path to data plane path over the WG tunnel.
Keep confirm ALWAYS on NEW established WG tunnel (posthandshake with rekeying). We keep an active method
irrelevant of the WG handshake (we might decide that the indirect wg handshake is sufficient in the future).
Optimistic commit on responder(when sending answer), while on initiator we set it on getting the answer
- Have just one manager => one lock
- Session state is needed in driver to => we have it available now.
- Isomorphically align to rosenpass components and functionality
File Role rosenpass equivalent
kem.go primitive pure X25519MLKEM768 crypto.go/handshake
message.go Offer/Answer/Confirm + Encode/Decode messages.go
manager.go Manager stateful, single lock server logic
callbacks.go WGCallbackHandler (seam output) Handler
Transport (interfaccia) seam trasporto pluggable Conn
riccardom