at88sc018 ATMEL Corporation, at88sc018 Datasheet - Page 20

• Manufacturer Part Number: at88sc018
• Description: Cryptocompanion? Chip For Cryptomemory And Cryptorf
• Manufacturer: ATMEL Corporation

3.7.
3.8.
3.9.
20
Encryption_1
Similar to Auth_1, this sequence generates an intermediate value used for subsequent encryption of data to/from CRF.
This pass through the crypto engine is similar to the computation done during authentication with the exceptions that G
is replaced by S, the input C is replaced with the AT88SC018 register C, and Q
AT88SC018. See
A valid authentication sequence must be run before these commands, which will have set up the C & S registers. This
command (and its mate, Encryption_2) can be run multiple times per authentication sequence, but running it more than
once will cause the AT88SC018 to be out of synchronization with CRF until the next Auth_1/Auth_2 sequence is run.
After execution of Encryption_1, the next command must be Encryption_2. If not, the AT88SC018 will lock up for a
security delay.
Table 27.
Table 28.
Encryption_2
Similar to Auth_2, this sequence takes the encryption response from CRF and compares it the value computed at the
end of Encryption_1.
This command can only be run after the execution of Encryption_1. If the incoming Ci
AT88SC018 locks up for a security delay (refer to
AuthFail.
Table 29.
Table 30.
GrindBytes
Passes a variable number of bytes through the crypto engine on the AT88SC018 and sends the output of the crypto
engine back to the system. This command is used to keep the AT88SC018 in sync with the crypto engine on the CRF
chip, to decrypt encrypted data read from CRF, to encrypt data to be written to CRF and to generate or verify a
checksum.
The AT88SC018 does not interpret these bytes, merely passes them through the crypto engine.
GrindBytes cannot be run prior to the successful execution of the Auth_2 nor after the execution of the Clear command.
There is a limit of 4096 for maximum number of GrindBytes that can be run per Authentication.
CryptoCompanion Chip
Q
CH
Ci
E
E
E
Name
Name
Name
Name
Inputs
Outputs
Inputs
Outputs
Section 2.2
Size
Size
Size
Size
8
8
8
Random number for encryption sequence
Encryption challenge from AT88SC018 to CRF
Authentication response from CRF to the AT88SC018
for more details on the encryption algorithm.
Section
1.6.3) and sets the error code in the status register to
Description
Description
Description
Description
E
is newly generated by the RNG on the
E
value is incorrect, the
5277C–CryptoCompanion–9/09