
AES hardware accelerator (AES)
RM0453
672/1454
RM0453 Rev 2
A typical message construction for GMAC is given in
.
Figure 120. Message construction in GMAC mode
AES GMAC processing
describes the GMAC mode implementation in the AES peripheral. This mode is
selected by writing 011 to the CHMOD[2:0] bitfield of the AES_CR register.
Figure 121. GMAC authentication mode
The GMAC algorithm corresponds to the GCM algorithm applied on a message only
containing a header. As a consequence, all steps and settings are the same as with the
GCM, except that the payload phase is omitted.
Suspend/resume operations in GMAC
In GMAC mode, the sequence described for the GCM applies except that only the header
phase can be interrupted.
MSv42158V2
Authenticated data
16-byte
boundaries
0
Len(A)
[Len(A)]
64
Last
block
[0]
64
Authentication tag (T)
ICB
4-byte boundaries
Counter
Initialization vector (IV)
Zero padding
auth.
MSv42150V2
(4) Final
(1) Init
(2) Header
AES_KEYRx (KEY)
input
output
Legend
XOR
AES_KEYRx (KEY)
AES_IVRx
IV + 32-bit counter (= 0x0)
Encrypt
[0]
128
H
AES_DINR
(message block 1)
Swap
management
Swap
management
AES_DINR
(message block n)
GF2mul
DATATYPE
[1:0]
GF2mul
H
H
GF2mul
H
AES_DINR
len(A)
64
|| [0]
64
AES_DOUTR
(authentication tag T)
S
Encrypt