Key Register
Authentication
Result (TAG)
AES Core
(encrypt)
128
128
Key in
128
data_out
Input Buffer
(plain text)
IV Register
128
128
128
data_in
Key Register
Input Buffer
(plain text)
AES Core
(encrypt)
128
128
Key in
256
data_out
128
128
Ouput Buffer
(cipher text)
data_in
IV register
Temporary Buffer
128
128
128
128
Key Register
Input Buffer
(cipher text)
AES Core
(decrypt)
128
128
Key in
256
data_out
128
128
Ouput Buffer
(plain text)
data_in
IV register
Temporary Buffer
128
128
128
128
Encryption
Decryption
AES Functional Description
667
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Advance Encryption Standard Accelerator (AES)
Figure 9-7. AES – XTS Operation
NOTE:
The IV is created with an initial encryption, followed by an LFSR operation for each new
block.
9.2.3.1.7 F9 Operation
shows the F9 authentication mode of operation, where the input to the cryptographic core is
XORed with the IV, and the output is XORed with the previous result to create the next result. The
cryptographic core output is fed back as IV for the next block. The result is the output of the last XOR
operation of the cryptographic core output.
Figure 9-8. AES – F9 Operation