9.4.9.1 Functional

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

If the maximum number of trials has been exceeded, the device will return $69 $00 instead of the INS code, after receiving the header, to indicate that the command is unauthorized. To prevent replay attacks, the device decrements the Associated Attempts Counter before verifying the password. If the password is correct, the device memorizes this success, clears the attempts counter and returns $90 $00. If the password is incorrect, the device simply returns $69 $00 after decrementing the attempts counter. The Write 7 password is also known as the secure code and must be properly presented before write access to the configuration memory is granted when personalizing the device.