AES-GCM Crypto Engine

Modes of Operation

The AESG-X256 family of IP Cores provides low-latency AES encryption in three implementations to trade off resource utilisation and throughput. The engine includes a Control Unit to manage the parallel execution of the block cipher and the GHASH Authentication module. It supports the following NIST SP 800-38 modes:

• GCM/GMAC: provides Authenticated Encryption and Decryption with Associated Data (AEAD). GMAC is applied when all the bytes in a message are labelled as Additional Authenticated Data (AAD).
• CTR: encrypts and decrypts XORing the input data blocks with a pseudorandom sequence internally generated with the AES cipher.
• ECB: encrypts input data with the AES cipher to generate a ciphertext.

Other modes of operation may be implemented based on the AESG-X256 engine:

• CFB, OFB: chaining modes using the ECB encryptor.
• CCM, EAX: using the CTR encryptor and decryptor.

Interfaces

The IP Cores implement six AXI4-Stream interfaces for Initialisation Vector and Key configuration, and transfer of Input/Output Data and Tag.

One AXI4-Lite provides access to the register map to configure the key size, mode of operation, authentication tag length, zeroisation, and AAD forwarding.

An input port is used to select encryption or decryption for each message. Status and Tag Verification ports are also available for events and tag validity notifications.