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.
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