AT88SC0104C datasheet(36/58 Pages) ATMEL

36 / 58 page

5210B–SMIC–11/08

AT88SC0104/0204/0404/0808/1616/3216/6416/12816/25616C

7.6.5

Verify Password : $BA

7.6.5.1

Functional

Figure 7-10. Verify Password Command Functional Description

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 :

r = 0: Write password,

r = 1: Read password,

p2p1p0: Password set number.

Figure 7-11. 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.

7.7

Initialization Example

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.

Device

Command

Password Index

PW1

PW2

PW3

Host

3 password bytes

Command

PW Index

Parameter 2

Data x 3

1011 1010

000r 0p2p1p0

xxxx xxxx

0000 0011

d7--- ---d0

N=3

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