AT88SC1616C ATMEL [ATMEL Corporation], AT88SC1616C Datasheet - Page 7

• Manufacturer Part Number: AT88SC1616C
• Manufacturer: ATMEL [ATMEL Corporation]

Password
Verification
Authentication
Protocol
Checksum
2030AS–09/01
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 pass-
word 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.
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:
Figure 4. Password and Authentication Operations
The AT88SC1616C implements a data validity check function in the form of a checksum,
which may function in standard, authentication or encryption modes.
In the standard mode, the checksum is implemented as a Modification Detection Code (MDC),
in which the host may read a MDC from the device in order to verify that the data sent was
received correctly.
In the authentication and encryption modes, the checksum becomes more powerful since it
provides a bidirectional data integrity check and data origin authentication capability in the
form of a Message Authentication Code (MAC). Only the host/device that carried out a valid
authentication is capable of computing a valid MAC. While operating in the authentication or
encryption modes, the use of a MAC is required. For an ingoing command, if the device calcu-
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.
Checksum (CS)
VERIFY RPW
VERIFY CS
Write DATA
DATA
VERIFY CS
CS
AT88SC1616C
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