at88sc0104c ATMEL Corporation, at88sc0104c Datasheet - Page 37

• Manufacturer Part Number: at88sc0104c
• Description: Cryptomemory Specification For Standard Mode Of Operation
• Manufacturer: ATMEL Corporation

7.6.5
7.6.5.1
Figure 7-11. Verify Password Command Functional Description
7.7
5210A–SMIC–04/07
Initialization Example
Verify Password : $BA
Functional
3 password bytes
Read password indices : $10 to $17 for passwords 0 to 7.
Write password indices : $00 to $07 for passwords 0 to 7.
Secure code index : $07 (equivalent to Write 7 password).
Four password index bits "r" and "ppp" indicate the password to compare :
Figure 7-12. Verify Password
Once the sequence has been carried out, the device requires the host to perform an ACK polling
sequence with the system read command $B6. In order to know whether the inserted password
was correct, the host can read the corresponding attempts counter and verify the value is $FF.
The first step in initializing CryptoMemory is to determine what data is to be stored in the device
and what the security settings need to be to protect this data. Once defined, determine the
proper settings for CryptoMemory registers and select values for passwords. To initialize the
CryptoMemory device, the following sequence is recommended to take place in a secure loca-
tion to protect sensitive data and passwords that may be loaded into the device.
R
S
T
A
T
r = 0: Write password,
r = 1: Read password,
p2p1p0: Password set number.
Command
1011 1010
AT88SC0104/0204/0404/0808/1616/3216/6416/12816/25616C
C
A
K
000r 0p2p1p0
Password Index
PW Index
Command
Host
PW1
PW2
PW3
A
C
K
Parameter 2
xxxx xxxx
A
C
K
0000 0011
N=3
Device
A
C
K
Data x 3
d7--- ---d0
A
C
K
O
S
T
P
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