ST STM32F207 Series Reference Manual page 523

RM0033
DATATYPE in
Swapping performed
CRYP_CR
10b
11b
Figure 207
bit words popped off the IN FIFO by the CRYP processor, according to the DATATYPE
value. The same schematic can easily be extended to form the 128-bit block for the AES
cryptographic algorithm (for the AES, the block length is four 32-bit words, but swapping
only takes place at word level, so it is identical to the one described here for the TDES).
Note: The same swapping is performed between the IN FIFO and the CRYP data block, and
between the CRYP data block and the OUT FIFO.
Table 74. Data types
Byte (8-bit) swapping
Bit swapping
shows how the 64-bit data block M1...64 is constructed from two consecutive 32-
System memory data
(plaintext or cypher)
Example: TDES block value 0xABCD77206973FE01 is
represented in system memory as:
TDES block size = 64bit = 2x 32 bit
0xAB CD 77 20 69 73
TDES block value 0x4E6F772069732074
memory as:
TDES Bloc size = 64bit = 2x 32 bit
0x4E 6F 77 20 69 73 20 74
0100 1110 0110 1111 0111 0111 0010 0000
0110 1001 0111 0011 0010 0000 0111 0100
RM0033 Rev 9
Cryptographic processor (CRYP)
system memory
0x 20 77
FE 01
0x 01 FE
is represented in system
system memory
0x04 EE F6 72
0x2E 04 CE 96
0000 0100 1110 1110
0010 1110 0000 0100
CD AB
@
@+4
73 69
@
@+4
1111 0110 0111 0010
@
1100 1110 1001 0110 @+4
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