AT88SA102S_11 ATMEL [ATMEL Corporation], AT88SA102S_11 Datasheet - Page 14

• Manufacturer Part Number: AT88SA102S_11
• Description: Atmel CryptoAuthentication Product Authentication Chip
• Manufacturer: ATMEL [ATMEL Corporation]

6.1
MAC
Computes a SHA-256 digest of a key stored inside the chip, an input challenge and other information on the chip. The output
of this command is the digest of this message.
If the message includes the serial number of the chip, then the response is said to be diversified. Protocols that utilize
diversified responses may be more secure because two AT88SA102S chips with same key will return different responses to
an identical challenge based on their unique serial number.
Table 6-1.
Table 6-2.
Regardless of the value of mode, the first 512-bit block of the message that will be hashed with the SHA-256 algorithm will
consist of:
The second block consists of the following information:
Opcode
Param1
Param2
Data
Name
Response
256-bits key[KeyID]
256-bits challenge
8-bits
8-bits
16-bits KeyID
64-bits Secret Fuses including BurnFuse and BurnSecure enable (or zeros, see Table 6-3)
24-bits Status Fuses including FuseDisable (or zeros, see Table 6-3)
8-bits
32-bits Fuse SN, (Fuse[96:127]) (or zeros, see Table 6-3)
16-bits ROM MfrID (never zero’d out)
16-bits ROM SN (or zeros, see Table 6-3)
1-bit
255-bit ‘0’ pad
64-bit
Input Parameters
Output Parameters
Opcode (always 0x08)
Mode
Fuse MfrID fuses, (Fuse[88:95]) (never zero’d out)
‘1’ pad
Total length of message in bits (512+192=704), excluding pad and length
Name
MAC
Mode
KeyID
Challenge
Size
32
Notes
SHA-256 digest
Size
1
1
2
32
Notes
0x08
Controls which fields within the chip are used in the message
Which internal key is to be used in the message
Input portion of message to be digested
Atmel AT88SA102S [DATASHEET]
8584G−CRYPTO−9/11
14