AT88SC25616C

13

5017KJS–SMEM–08/09

12.

Password Verification

Passwords may be used to protect read and/or write access of any user zone. When a valid password is presented, it

is memorized and active until power is turned off, unless a new password is presented or RST becomes active. There

are eight password sets that may be used to protect any user zone. Only one password is active at a time, but write

passwords give read access also.

12.1.

Authentication Protocol

The access to a user zone may be protected by an authentication protocol. Any one of four keys may be selected to

use with a user zone.

The authentication success is memorized and active as long as the chip is powered, unless a new authentication is

initialized or RST becomes active. If the new authentication request is not validated, the card loses its previous

authentication and it should be presented again. Only the last request is memorized.

Note

:

Password and authentication may be presented at any time and in any order. If the trials limit has been

reached (after four consecutive incorrect attempts), the password verification or authentication process will not

be taken into account.

Figure 13.

Password and Authentication Operations

Device (Card)

Card Number

VERIFY A

COMPUTE Challenge B

Challenge B

VERIFY RPW

DATA

Checksum (CS)

VERIFY WPW

VERIFY CS

Write DATA

Host (Reader)

COMPUTE Challenge A

Challenge A

VERIFY B

Read Password (RPW)

VERIFY CS

Write Password (WPW)

DATA

CS

AUTHENTICATION

READ ACCESS

WRITE ACCESS