AT88SC0404CA-Y6H-T Atmel, AT88SC0404CA-Y6H-T Datasheet - Page 39

• Manufacturer Part Number: AT88SC0404CA-Y6H-T
• Description: IC EEPROM 4KBIT 4MHZ 8MAP
• Manufacturer: Atmel
• Series: CryptoMemory®r

Specifications of AT88SC0404CA-Y6H-T

• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Memory Size: 4K (512 x 8)
• Speed: 4MHz
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-UDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

38
When the device receives the Verify CRYPTO command, it computes a challenge based on the received random
number, Q, the internally stored associated Cryptogram, C
device also decrements the associated attempts counter. It then compares the computed challenge with the challenge
sent by the host. If the challenges match, the device computes and writes a new C
success or failure information of the authentication process and updates the attempts counter accordingly.
Key index:
Data:
Figure 26. Verify CRYPTO
Once the sequence has been carried out, the device requires the host to perform an ACK polling with either the Read
User Zone $B2 command or System READ $B6 command. To verify whether the authentication succeeded, the host
could either read the associated attempts counter to confirm the value is $FF, or read the post authentication
cryptogram from the device and compare with the cryptogram generated when the host computed the challenge bytes.
Atmel AT88SC0104/0204/0404/0808/CA
R
S
T
A
T
Command
b0000_00nn : Secret Seed G
b0001_00nn : Session Encryption Key S
Q : Host random number, 8 bytes
CH : Host challenge, 8 bytes
1011 1000
C
A
K
Key Index
000e 00nn
0
A
C
K
-G
3
Parameter 2
xxxx xxxx
0
-S
3
C
A
K
0001 0000
N=16
i
, and Secret Seed, G
A
C
K
Data x 16
d7--- ---d0
i
(or Session Encryption Key, S
A
C
K
i
S
O
P
T
and S
i
. The device utilizes the
8664C–CRYPT–01/10
i
). The