Key Register
IV Register
Input Buffer
(plain text)
Authentication Result
(TAG
AES Core
(encrypt)
128
128
128
128
Key in
data_in
data_out
128
256
Temporary Buffer
128
AES Functional Description
668
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Advance Encryption Standard Accelerator (AES)
9.2.3.1.8 CBC-MAC Operation
shows the CBC-MAC authentication mode of operation, where the input to the cryptographic
core is XORed with the IV. The cryptographic core output is then fed back as IV for the next block. The
last data input block is XORed with an additional input value stored in the temporary buffer; this can be
any precalculated value and is dependent on the alignment of the last input block. The result is the
cryptographic core output of the last encryption operation.
Figure 9-9. AES – CBC-MAC Authentication Mode