Hybrid (classical crypto + PQ) TLS in CCF

[maxtropets]

For both user-to-node and node-to-node, details TBD. Use of PQ or hybrid certs is still undefined. A minimum acceptance criteria would be to enable hybrid secret exchange to protect from HNDL attacks.

---

Progress

• User TLS (Hybrid TLS secret exchange #8107)
• N2N (needs replacing custom channels with TLS 1.3 + QUIC)