RM0319 datasheet(308/368 Pages) STMICROELECTRONICS

308 / 368 page

Security co-processor (C3)

RM0319

308/368

Doc ID 022640 Rev 3

Bit ‘a’ in the above table is used to set the operation to perform.

Bits 15 to 0 in the first instruction word (cccc in Table 101) represent the length in Bytes of

the data to be processed.

CBC

The AES APPEND CBC instruction is 3 words long. This instruction is used for passing the

data to process (encrypt or decrypt). The length of the data to process is encoded in the first

instruction word, the second word represents the Source Address and the third word

represents the Destination Address.

Bit ‘a’ in the above table is used to set the operation to perform and has the same encoding

as in the ECB instruction (Table 101). Bits 15 to 0 in the first instruction word (cccc in

Table 102) represent the length in Bytes of the key.

CTR

The AES APPEND CTR instruction is 3 words long. This instruction is used for passing the

data to process (encrypt or decrypt). The length of the data to process is encoded in the first

instruction word, the second word represents the Source Address and the third word

represents the Destination Address.Address.

Table 101.

AES ECB APPEND instruction bit encoding

Bit Encoding

xxxx 10xa 100x xxxx cccc cccc cccc cccc

32 bit Source Address for the data

32 bit Destination Address for the data

Bit 24

Description

aOperation

Encryption

1Decryption

Table 102.

AES CBC APPEND instruction bit encoding

Bit Encoding

xxxx 10xa 101x xxxx cccc cccc cccc cccc

32 bit Source Address for the data

32 bit Destination Address for the data

Table 103.

AES CTR APPEND instruction bit encoding

Bit Encoding

xxxx 10xa 110x xxxx cccc cccc cccc cccc

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