ATAES132_14 Datasheet, PDF (21/171 Pages) ATMEL Corporation – 32K AES Serial EEPROM Specification

KeyConfig Field
TransferOK
AuthCompute
LinkPointer
CounterNum
Byte
1
Bit Description
1b = The key is permitted to be the target of a KeyTransfer command (see
6
Section 7.16).
0b = KeyTransfer command is prohibited.
1
7
1b = The key can be used with the AuthCompute command.
0b = The key cannot be used with the AuthCompute command.
For child keys; stores the ParentKeyID.
2
0 to 3 _{For all other keys; the KeyID of the authorizing key (see AuthKey).}
Stores the CntID of the Monotonic Counter attached to this key for usage limits or for
2 4 to 7 MAC calculation. MAC calculations will include the Counter if Command Mode bit 5 is
1b even if key usage limits are disabled.
Reserved
3 0 to 7 Reserved for future use. All bits must be 0b.
Notes: 1.
2.
3.
4.
Changes to the KeyConfig Registers take effect immediately which allows the functionality to be
verified during the personalization process.
Warning: ATAES132 must always be locked by the customer prior to shipment to the end user to
protect the customer secrets. See Section 7.18, Lock Command.
Warning: Since the Encrypt command does not include an input MAC, the Encrypt command can
exhaustively be run with selected input data to attack the key. Requiring authentication prior to
allowing encryption makes these attacks more difficult. To require prior authentication, the AuthKey
and RandomNonce bits must be set to 1b.
A key can be disabled by setting KeyConfig[KeyN].AuthKey to 1b, and KeyConfig[KeyN].LinkPointer
to contain “KeyN”, where KeyN = KeyID of the key being configured.
ATAES132 [Datasheet]
21
Atmel-8760C-CryptoAuth-ATAES132-Datasheet_102013