at88sa102s ATMEL Corporation, at88sa102s Datasheet - Page 15

• Manufacturer Part Number: at88sa102s
• Description: Cryptoauthentication
• Manufacturer: ATMEL Corporation

4.1.
8584A–SMEM–03/09
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 CryptoAuthentication chips with same key will return different
responses to an identical challenge based on their unique serial number.
Table 7.
Table 8.
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:
Mode is encoded as follows:
Opcode
Param1
Param2
Data
Response
256 bits
256 bits
8 bits
8 bits
16 bits
64 bits
24 bits
8 bits
32 bits
16 bits
16 bits
1 bit
255 bit
64 bit
Name
Input Parameters
Output Parameters
MAC
Mode
KeyID
Challenge
key[KeyID]
challenge
Opcode (always 0x08)
Mode
KeyID
Secret Fuses including BurnFuse and BurnSecure enable (or 0’s, see below)
Status Fuses including FuseDisable (or 0’s, see below)
MfrID fuses, Fuse[88:95] (never zero’d out)
Serial Number Fuses, Fuse[96:127] (or 0’s, see below)
ROM MfrID (never zero’d out)
ROM SN (or 0’s, see below)
‘1’ pad
‘0’ pad
total length of message in bits (512+192=704), excluding pad and length
Name
Size
32
SHA-256 digest.
Size
32
1
1
2
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.
AT88SA102S [Preliminary]
Notes
Notes
15