X25519Kyber768 Hybrid Post-Quantum Key Exchange for HTTPS

[fac-trax]

Hybrid key exchange in SSL handshake using ML-KEM in addition to default already has significant usage thanks to Google and Cloudflare. It appears to only be supported currently in TLS 1.3 but is intended for TLS 1.2 as well.

[ghen2]

but is intended for TLS 1.2 as well

The IETF does not intend to backport PQ cryptography to TLS 1.2:
https://www.ietf.org/archive/id/draft-ietf-tls-tls12-frozen-02.html#name-implications-for-post-quant