Definition. Module-Lattice-Based Key Encapsulation Mechanism — the post-quantum key encapsulation mechanism standardised by NIST in FIPS 203. Based on the CRYSTALS-Kyber scheme. ML-KEM is typically used in hybrid TLS handshakes (e.g. X25519MLKEM768), combining classical ECDH with ML-KEM to provide security against both classical and quantum adversaries simultaneously.

Why relevant. TLS 1.3 with a hybrid ML-KEM handshake is already deployable in production today — Caddy and current Chrome versions support X25519MLKEM768. The hybrid approach protects live connections against harvest-now-decrypt-later attacks without breaking interoperability.

Related.ML-DSA, Post-Quantum Cryptography, Crypto Agility, Harvest-now-decrypt-later, Lattice-based cryptography