ML-KEM
FIPS 203, formerly CRYSTALS-Kyber
The NIST-standardised post-quantum key encapsulation mechanism, used to establish a shared secret over an untrusted network. It is the replacement for RSA key transport and elliptic-curve Diffie-Hellman.
In practice
Parameter sets are ML-KEM-512, ML-KEM-768 and ML-KEM-1024. ML-KEM-768 is the common default for TLS.
Related terms
A construction for securely establishing a shared symmetric key: the sender encapsulates a random secret under the recipient's public key, and the recipient decapsulates it with their private key. Both then hold the same secret.
Combining a classical algorithm with a post-quantum one so the result stays secure as long as either component holds. It hedges against both a future quantum attack and an undiscovered flaw in the newer post-quantum scheme.
The NIST-standardised lattice-based digital signature algorithm, intended as the general-purpose post-quantum replacement for RSA-PSS and ECDSA. Signatures are larger than ECDSA but performance is practical for most uses.
The three post-quantum standards NIST finalised in August 2024: FIPS 203 (ML-KEM) for key establishment, FIPS 204 (ML-DSA) for general-purpose signatures, and FIPS 205 (SLH-DSA) for hash-based signatures.