The AES-GCM encryption IP core implements Rijndael encoding and decoding in compliance with the NIST Advanced Encryption Standard. It processes 128-bit blocks, and is programmable for 128-, 192-, and 256-bit key lengths.
Four architectural versions are available to suit system requirements. The Standard version (AES-GCM-S) is more compact, using a 32-bit datapath and requiring 44/52/60 clock cycles for each data block (128/192/256-bit cipher key, respectively). The Fast version (AES-GCM-F) achieves higher throughput using a 128-bit datapath and requiring 11/13/15 clock cycles for each data block depending on key size.
For applications where throughput is critical there are two additional versions. The High Throughput AES-GCM-X can process 128 bits/cycle and the Higher Throughput AES-GCM-X2 can process 256 bits/cycle respectively independent of the key size.
GCM stands for Galois Counter. GCM is a generic authenticate-and-encrypt block cipher mode. A Galois Field (GF) multiplier/accumulator is utilized to generate an authentication tag while CTR (Counter) mode is used to encrypt.
