SWCU194 March 2023 CC1314R10 , CC1354P10 , CC1354R10 , CC2674P10 , CC2674R10
The composition of the AES core is as follows:
The AES core operates on the input block and performs the required substitution, shift, and mix operations. For each round, the encryption core receives the proper round key from the AES key scheduler. A fundamental component of the AES algorithm is the S-box. The S-box provides a unique 8-bit output for each 8-bit input.
The architecture of the AES decryption core is generally the same as the architecture of the encryption core. One difference is that the generation of round keys for decryption requires an initial conversion of the input key (always supplied by the host in the form of an encryption key) to the corresponding decryption key. This conversion is done by performing a dummy encryption operation and storing the final round key as a decryption key. The key scheduler is then reversed to generate the round keys for the decryption operation. Consequently, for each sequence of decryption operations under the same key, a single throughput reduction equal to the time to encrypt a single block occurs. When a decryption key is generated, subsequent decryption operations with the same key use this generated decryption key directly.