Example Applications - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 363

Figure 13.34 Ignition key with integral transponder (reproduced by permission of Philips Elec-

tronics N.V.)

generator in the vehicle reader. It is therefore impossible to duplicate the transpon-
der if this system is used. If several keys are used with one vehicle then each key
runs through its own pseudo-random sequence.

• Cryptographic procedures (authentication) with fixed keys. The use of crypto-

graphic procedures offers much greater security (second generation immobilisation).
In the authentication sequence (challenge response) knowledge of a secret (binary)
key is checked, without this key being transmitted (see Chapter 8). In vehicle appli-
cations, however, unilateral authentication of the key transponder by the reader in
the ignition lock is sufficient.

The RFID reader now communicates with the vehicle's motor electronics , although
this communication is protected by cryptographic procedures. The motor electronics
control all important vehicle functions, in particular the ignition system and fuel system.
Simply short circuiting or disconnecting certain cables and wires is no longer sufficient
to circumvent an electronic immobilisation system (Figure 13.36). Even attempting to
fool the motor electronics by inserting another ignition key of the same type into the
ignition lock is bound to fail because of the authentication procedure between reader
and motor electronics. Only the vehicle's own key has the correct (binary) key to
successfully complete the authentication sequence with the motor electronics.