RM0033 Rev 9 523/1381
RM0033 Cryptographic processor (CRYP)
543
Figure 207 shows how the 64-bit data block M1...64 is constructed from two consecutive 32-
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.
10b Byte (8-bit) swapping
Example: TDES block value 0xABCD77206973FE01 is
represented in system memory as:
11b Bit swapping
TDES block value 0x4E6F772069732074 is represented in system
memory as:
Table 74. Data types
DATATYPE in
CRYP_CR
Swapping performed
System memory data
(plaintext or cypher)
0xAB CD 77 20 69 73 FE 01
TDES block size = 64bit = 2x 32 bit
0x 20 77 CD AB
0x 01 FE 73 69
@
@+4
system memory
0x4E 6F 77 20 69 73 20 74
0x04 EE F6 72
0x2E 04 CE 96
@
@+4
0000 0100 1110 1110 1111 0110 0111 0010
0100 1110 0110 1111 0111 011 1 0010 0000
0110 1001 0111 0011
0010 0000 0111 0100
0010 1110 0000 0100 1100 1110 1001 0110
@
@+4
system memory
TDES Bloc size = 64bit = 2x 32 bit
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