46.5.3 Galois Counter Mode (GCM)

GCM is comprised of the AES engine in CTR mode along with a universal hash function (GHASH engine) that is defined over a binary Galois field to produce a message authentication tag. The GHASH engine processes data packets after the AES operation. GCM provides assurance of the confidentiality of data through the AES Counter mode of operation for encryption. Authenticity of the confidential data is assured through the GHASH engine. Refer to the “NIST Special Publication 800-38D Recommendation” for additional information.

GCM processing is computed on 128-bit input data fields. There is no support for unaligned data. The AES key length can vary depending on what is supported by the AES module.