at88sc0104c ATMEL Corporation, at88sc0104c Datasheet - Page 23

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

5.3.10.3
5.3.11
5.3.12
5.3.13
5.3.14
5.3.15
5.3.16
5.3.17
5.3.18
5.4
5210A–SMIC–04/07
Security Fuses
Identification Number
Cryptograms
Session Keys
Secret Seeds
Password Sets
Secure Code
Password Attempts Counters (PAC)
Authentication Attempts Counters (AAC)
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.
A 56-bit number the customer defines during personalization. It is recommended that a unique
identification number be assigned to each device.
Cryptograms are applicable to authentication and encryption modes of operation.
Session keys are applicable to authentication and encryption modes of operation.
Secret Seeds are applicable to authentication and encryption modes of operation.
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.
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.
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.
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.
The authentication attempts counters are applicable in authentication and encryption modes of
operation only.
CryptoMemory uses four fuses. The status of these fuses is given in a ‘fuse byte.’ A value of ‘0’
indicates that the fuse has been blown. Bits 4 to 7 of this byte are not used as Security Fuses
and are reserved for Atmel use
Table 5-2 on page 16
AT88SC0104/0204/0404/0808/1616/3216/6416/12816/25616C
shows the secure codes for the various devices as they leave the
19