Chrome Default Hybrid Post-Quantum Key Exchange (X25519Kyber768 → ML-KEM)

Adopt with guardrails

Why

Hybrid post-quantum key exchange is now shipped by default across Chrome, Firefox and Edge with real and growing traffic share (Cloudflare measured ~38% of HTTPS traffic using hybrid PQ key exchange as of March 2025, per a secondary source republishing that figure in April 2026), making it a low-friction, already-proven default to rely on — but the documented ClientHello-size middlebox breakage and the fact that authentication stays classical mean it should be treated as one defense-in-depth layer, not a complete quantum-safety guarantee.

Next

Confirm the Cloudflare edge (and any bespoke TLS termination in the stack) already negotiates X25519MLKEM768 by default with current-generation browsers; add handshake-size / middlebox regression checks before any canary that touches TLS-adjacent infrastructure (proxies, WAF, corporate egress); track the separate post-quantum signature/authentication rollout (ML-DSA/FIPS 204, already tracked via the NEAR Protocol Quantum-Safe Signing entry) before treating any TLS session as fully quantum-safe end-to-end.