AT88SA102S_10 ATMEL [ATMEL Corporation], AT88SA102S_10 Datasheet - Page 14

• Manufacturer Part Number: AT88SA102S_10
• Description: Atmel CryptoAuthentication
• Manufacturer: ATMEL [ATMEL Corporation]

5.
5.1.
14
Commands
The command packet is broken down in the following way:
If a command fails because the CRC within the block is incorrect or there is some other communications error
then immediately after t
packet. The value of that byte will be all ones. In this situation, the system should re-transmit the command block
including the proceeding Transmit flag – providing there is sufficient time before the expiration of the watchdog
timeout.
If the opcode is invalid, one of the parameters is illegal, or Atmel
execution of this command then immediately after t
block containing a single byte packet. The value of that byte will be 0x0F. In this situation, the condition must be
corrected before the (modified) command is sent back to AT88SA102S.
If a command is received successfully then after the appropriate execution delay the system will be able to
retrieve the output block as described in the individual command descriptions below.
In the individual command description tables below, the Size column describes the number of bytes in the
parameter documented in each particular row. The total size of the block for each of the commands is fixed,
though that value is different for each command. If the block size for a particular command is incorrect, the chip
will not attempt the command execution and return an error.
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 5-1.
Atmel AT88SA102S
Byte
0
1
2-3
4 +
Opcode
Param1
Param2
Data
Name
Opcode
Param1
Param2
Data
Input Parameters
Name
MAC
Mode
KeyID
Challenge
PARSE
Meaning
The Command code
The first parameter – always present
The second parameter – always present
Optional remaining input data
the system will be able to retrieve an error response block containing a single byte
Size
32
1
1
2
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
PARSE
the system will be able to retrieve an error response
®
AT88SA102S is in an illegal state for the
8584F–SMEM–8/10