MAX32665-MAX32668 User Guide
Maxim Integrated Page 434 of 457
For the CFB mode of operation, the mode size is equal to the block size. 128-bit CFB is supported for AES, and 64-bit CFB is
supported for TDEA. 1-bit CFB and 8-bit CFB are not supported. For the CTR mode of operation, the lower 32-bits of the
initial vector increment.
Block cipher operations set CRYPTO_CTRL.cph_done = 1 and when complete.
23.2.1 Cipher Key Storage and Initialization
Block cipher operations requires a user-supplied cipher key to be loaded into CIPHER_KEY[7:0] before any algorithm can be
executed. The cipher key is loaded into non-volatile memory during a secure bootloader session, and restored to the
AES_KEY[3:2], registers following a power-on reset.
The length of the key is dependent on the specific algorithm used.