I'm working with the MCF52259 processor which includes the CAU (Cryptographic Acceleration Unit).
I wish to implement a simple AES256 decryption. In reading the NXP document (AN4307) "Using the CAU and mmCAU in ColdFire, ColdFire+, and Kinetis", section 2.3 specifically states that the crypto algorithms are executed in Cipher-block chaining (CBC) modes.
NXP document (AN4234) "Using the Cryptographic Service Engine (CSE)", section 1.2 discusses the Electronic Codebook (ECB) and the Cipher-block chaining (CBC). This document does not indicate which mode is used in the CAU, nor does it indicate if there is any ability to specify the mode.
When I read the NXP document "Colfire/ColdFire+ CAU and Kinetis mmCAU Software Library" user guide, revision 2.3, there are only 3 library commands associated with the AES encryption/decryption methodology; cau_aes_set_key, cau_aes_encrypt, and cau_aes_decrypt. If the AES methodolgy implemented in the CAU does indeed use the CBC mode, then there must be some manner in which I can provide the "initialization value" (commonly listed in AES documentation as IV), in addition to the key. I guess the other possibility is that the CBC mode is not really being used, but rather the ECB mode, which does not require the IV value.
Can anyone shed a little light on this for me?