6

AT88RF04C

8672AS–CRRF–04/09

11.2. Password Verification

Passwords may be used to protect user zone read and/or write access. When a password is presented using the

Check Password command, it is memorized and active until power is removed unless a new password is presented or

a valid DESELECT or IDLE command is received. Only one password is active at a time, but write passwords also give

read access.

11.3. Authentication Protocol

The access to a user zone may be protected by an authentication protocol in addition to password dependent rights.

Passwords are encrypted in Authentication Communication Security mode. The authentication success is memorized

and active as long as the chip is powered, unless a new authentication is initialized or a valid DESELECT or IDLE

command is received. If the new authentication request is not validated, the card loses its previous authentication and it

must be presented again. Only the last request is memorized.

11.4. Encryption

The data exchanged between the card and the reader during Read, Write, and Check Password commands may be

encrypted to ensure data confidentiality.

The issuer may choose to protect the access to a user zone with an encryption key by settings made in the

configuration memory. In that case, activation of the Encryption Communication Security mode is required in order to

read/write data in the zone.

The encryption activation success is memorized and active as long as the chip is powered, unless a new initialization is

initiated or a valid DESELECT or IDLE command is received. If the new encryption activation request is not validated,

the card will no longer encrypt data during read operations nor will it decrypt data received during write or Check

Password operations.

11.5. Checksum

The PICC implements a data validity check function in the form of a checksum. The checksum may function in

standard or cryptographic mode. In the standard mode, the checksum is optional and may be used for transmission

error detection. The cryptographic mode is more powerful since it provides data origin authentication capability in the

form of a Message Authentication Code (MAC). To write data to the device, the host is required to compute a valid

MAC and provide it to the device. If after an ingoing command the device computes a MAC different from the MAC

transmitted by the host, not only is the command abandoned but the cryptographic mode is also reset. A new

authentication is required to reactivate the cryptographic mode.

11.6. Initial Device Programming

CryptoRF is delivered with all security features disabled. To program the polling response or enable the security

features of CryptoRF the device must be personalized by programming several registers. This is accomplished by

programming the configuration memory using simple write and read commands. AT88RF04C supports an optional

Secure Personalization mode which encrypts the secrets during programming.

11.7. Transport Password

To gain access to the configuration memory, a transport password known as the secure code must be presented using

the Check Password command. The transport password for AT88RF04C is $30 1D D2.

12.

Tuning Capacitance

The capacitance between the coil pins AC1 and AC2 is 82 pF nominal and may vary ±10 pF due to process variation.