Advanced Encryption Standard (AES)

Applies to. PCI DSS v4.0.1 does not name AES anywhere in its requirement text. The standard asks for strong cryptography, for example in 3.5.1 for stored PAN and 4.2.1 for PAN in transit, and leaves the choice of algorithm to the entity. AES is a symmetric algorithm that entities commonly choose to meet that expectation; whether a given deployment qualifies depends on key length and key management, not on the algorithm name alone.

Example. A merchant stores PAN in a database for recurring billing. The PAN column is encrypted with AES, the data-encrypting key is itself encrypted by a key-encrypting key held in a separate system, and the key-management procedures cover generation, distribution, storage and cryptoperiod. The assessor examines the encryption configuration and the key-management documentation rather than taking the algorithm name as proof.

Limits. Choosing AES does not by itself satisfy any requirement. A short or weak key, a key-encrypting key stored with the data-encrypting key it protects, or a key that is never changed leaves the deployment short of strong cryptography regardless of the algorithm. AES is a symmetric cipher: it does not provide digital signatures or key exchange, which need an asymmetric algorithm. The standard never mandates AES; other accepted algorithms can qualify.