CRYSTALS-Kyber

CRYSTALS-Kyber is a key encapsulation mechanism based on module learning with errors. Its underlying encryption uses polynomial-vector arithmetic with small secret and error coefficients; a transformation around that encryption supplies resistance to chosen-ciphertext attacks. Encapsulation produces a fresh shared secret and the ciphertext needed by the decapsulating party.^[ref]

Using a module structure reduces representation and computation costs compared with a fully unstructured matrix description. The security claim concerns the difficulty of the resulting noisy algebraic problem; the word lattice does not by itself prove resistance to every attack. ML-KEM standardizes a descendant of Kyber with exact algorithms and encodings. Applications must name the chosen version rather than treating Kyber and ML-KEM as byte-for-byte synonyms.