ST STM32F40 Series

Cryptographic processor (CRYP) RM0090
555/1422 Doc ID 018909 Rev 4
Figure 205. DES/TDES-CBC mode encryption
1. K: key; C: cipher text; I: input block; O: output block; Ps: plain text before swapping (when decoding) or
after swapping (when encoding); P: plain text; IV: initialization vectors.
IN FIFO
DEA, encrypt
K1
P, 64 bits
DEA, decrypt
K2
DEA, encrypt
K3
OUT FIFO
O, 64 bits
plaintext P
ciphertext C
64
64
64
Ps, 64 bits
swapping
+
IV0(L/R)
64
I, 64 bits
(before CRYP
is enabled)
O is written back
into IV at the
same time as it
is pushed into
the OUT FIFO
swapping
C, 64 bits
DATATYPE
DATATYPE
AHB2 data write
ai16070b