AT88SA100S-SH-CZ-T ATMEL [ATMEL Corporation], AT88SA100S-SH-CZ-T Datasheet - Page 17

• Manufacturer Part Number: AT88SA100S-SH-CZ-T
• Description: Atmel CryptoAuthentication Battery Authentication Chip
• Manufacturer: ATMEL [ATMEL Corporation]

6.5
LoadSram
Writes 256-bits into the battery backed SRAM and locks this memory against further modification. The value in the battery
backed SRAM cannot be read, it must be verified via the MAC command. If the secret value in the SRAM is already valid then
this command will fail with an error response. The only way to unlock the SRAM is to remove power from the AT88SA100S.
The input data (secret key) is always decrypted using the decryption digest previously generated by GenPersonalizationKey
prior to being written into the battery backed SRAM.
Note:
Table 6-11. Input Parameters
Table 6-12. Output Parameter
The AT88SA100S chip executes the following sequence on receipt of this command.
Opcode
Param1
Param2
Data
Name
Success
1.
2.
3.
4.
If the internal flag (indicating that a personalization key has been loaded) is not set, then return error. If the
Successively XOR each byte in the data (secret key) parameter with the corresponding byte from the personalization
Transfer the resulting bytes to the battery backed SRAM
Set MemValid (internal flag) to one
MemValid flag is set, return error
key generated by GenPersonalizationKey
Both the GenPersonalizationKey and LoadSram commands must be run consecutively within a single Wake
cycle prior to the expiration of the watchdog timer. If any command is inserted between these two operations
then LoadSram will fail.
Name
LOADSRAM
Zero1
Zero2
Key
Size
1
Notes
Upon successful execution, a value of 0 will be returned by the AT88SA100S chip
Size
32
1
1
2
Notes
0x10
Must be 0x00
Must be 0x0000
Encrypted value to be written into the SRAM
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
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