AT88SC0104C datasheet(22/58 Pages) ATMEL

22 / 58 page

5210B–SMIC–11/08

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

5.3.10.3

PW(2:0) – Password Set

These bits define which of the eight password sets must be presented to allow access to the

user zone when the password mode is selected.

5.3.11

Identification Number

A 56-bit number the customer defines during personalization. It is recommended that a unique

identification number be assigned to each device.

5.3.12

Cryptograms

Cryptograms are applicable to authentication and encryption modes of operation.

5.3.13

Session Keys

Session keys are applicable to authentication and encryption modes of operation.

5.3.14

Secret Seeds

Secret Seeds are applicable to authentication and encryption modes of operation.

5.3.15

Password Sets

The password fields contain eight sets of two 24-bit passwords for read and write operations.

The customer defines the values of these passwords during personalization. Successfully veri-

fying the Write password allows modification of the Read and the Write passwords of the same

set.

5.3.16

Secure Code

The secure code is Write 7 Password. Properly presenting this password grants write access to

the configuration memory during personalization. Atmel defines the initial values of the secure

code but the customer may change these values after successful verification of Write 7 pass-

word. Table 5-2 on page 16 shows the secure codes for the various devices as they leave the

Atmel factory. After blowing the PER fuse, verifying Write 7 password no longer grant write

access to the configuration memory, and the configuration memory becomes read-only

thereafter.

5.3.17

Password Attempts Counters (PAC)

Each of the sixteen PAC fields contains an 8-bit attempts counter for the verify password pro-

cess. Each PAC corresponds to a password. The attempts counter limits the number of

incorrect consecutive presentations of the corresponding password to four, after which it locks

the password from future use. The PAC will decrement ($FF, $EE, $CC, $88, $00) with each

incorrect attempt to present the password. The PAC permanently locks the corresponding pass-

word once its value reaches $00. Prior to reaching $00, any correct presentation of the

password resets the PAC value to $FF.

5.3.18

Authentication Attempts Counters (AAC)

The authentication attempts counters are applicable in authentication and encryption modes of

operation only.

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