at88sc018 ATMEL Corporation, at88sc018 Datasheet - Page 18

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

3.2.
3.3.
3.4.
18
Table 15.
Table 16.
Startup
The AT88SC018 resets all internal state, generates a 20 byte random number, and sends to system as challenge start.
To permit the system processor to mutually authenticate the AT88SC018, it will also compute a response to a
challenge from the system. CmcResponse = SHA-1(CmcChallenge, CmcSecret).
This command can be run only once per reset or power cycle.
Table 17.
Table 18.
ChallengeResponse
System sends 20 byte challenge response to the AT88SC018. The AT88SC018 computes SHA1 (SysChallenge,
SystemSecret) and compares with response. If incorrect, the AT88SC018 locks up until next time the reset pin is
asserted or power is removed.
The prior command must have been Startup, or the AT88SC018 will enter the RstLocked state.
Table 19.
Table 20.
Auth_1
Loads into the AT88SC018 the accessible information about the CRF for which authentication is to be computed and
builds the values needed for the CRF chip to perform its authentication sequence. This step computes the values of C
and S
Encrypt_1. See
Execution of this command automatically resets any previous state including C & S registers, and causes a reset of the
crypto engine state.
CryptoCompanion Chip
Digest
Signature
CmcChallenge
SysChallenge
CmcResponse
SysResponse
Name
Name
Name
Name
Name
Name
A
. These values are retained in volatile registers within the AT88SC018 (named C & S) for use during Auth_2 and
Inputs
Outputs
Inputs
Outputs
Inputs
Outputs
Section 2.2
Size
Size
Size
Size
Size
Size
20
20
20
20
20
20
for more details on the authentication algorithm.
Digest of external memory.
SHA-1(Digest, FlashDigest), ignored if Mode.Bit [1:0] = 00.
Authentication challenge to system processor from RNG
Challenge response to CmcChallenge
Calculated response from system
Authentication challenge to the AT88SC018 from system processor.
Description
Description
Description
Description
Description
Description
5277C–CryptoCompanion–9/09
A