ML-KEM (CRYSTALS-Kyber): standard, dates, parameters, and audit checklist
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ML-KEM is the NIST-standardized post-quantum key-encapsulation mechanism, published as FIPS 203 on 2024-08-13. It is derived from CRYSTALS-Kyber and is the primary algorithm for quantum-resistant key establishment.

Standard: FIPS 203
Standardized by: NIST (U.S. National Institute of Standards and Technology)
Date: 2024-08-13
Status: Final
Family: Lattice (Module-LWE)
Parameter sets: ML-KEM-512 (cat 1, pk 800 B, ciphertext 768 B); ML-KEM-768 (cat 3, pk 1184 B, ciphertext 1088 B); ML-KEM-1024 (cat 5, pk 1568 B, ciphertext 1568 B)
Audit focus: Timing leaks in compression and division (the KyberSlash class of bugs found in 2023-2024 across many Kyber implementations) | Correct implicit rejection in decapsulation (a rejected ciphertext must return a pseudorandom key, never an error signal) | Input validation required by FIPS 203: modulus check on encapsulation keys, hash check on decapsulation keys, ciphertext length checks | Constant-time NTT, sampling, and polynomial arithmetic; no secret-dependent branches or memory access | Randomness: fresh 32-byte seeds per encapsulation, no reuse of d/z across key generations | Hybrid combiners: shared-secret concatenation order and KDF binding to both ciphertexts, per RFC 10024 and SP 800-227 | Known-answer tests against the FIPS 203 final vectors (not the Round 3 Kyber vectors, which differ)
Auditors: zkSecurity, Trail of Bits, NCC Group (Cryptography Services), Cryspen, Kudelski Security, Quarkslab, Least Authority, Galois, atsec information security, Riscure (Keysight), Cure53, X41 D-Sec
Sources: https://csrc.nist.gov/pubs/fips/203/final | https://csrc.nist.gov/pubs/sp/800/227/final | https://datatracker.ietf.org/doc/rfc10024/ | https://datatracker.ietf.org/doc/rfc9935/ | https://kyberslash.cr.yp.to/

Source page: https://pqaudit.org/algorithms/ml-kem/
Compiled by: PQC Audit Index editors (https://pqaudit.org/about/)
Last reviewed: 2026-09-12