Philips uses advanced, uncrackable cryptography in next generation car key immobiliser systems

Eindhoven, The Netherlands - 14 November 1996 - Philips Semiconductors will be further developing its 60 to 70 percent share of the car immobiliser market with the launch of its next generation of car immobiliser key technology - SECT (SECurity Transponder) - which is the first to use a cryptographic transponder embedded in the key. The key and the car both cryptographically process a random number, initially generated by the car. Access is only granted if the results are the same.

Any attempt to monitor the RF transmissions between the key and the car will only reveal a string of random numbers. A special code sequence, stored both in the key and the car and used to cypher the initial random number, is never transmitted making it impossible to deduce this code from the data flow between key and car.

Copying the key is impossible - the code cannot be determined. And it is impossible to use the car without a key that the system recognises. The car itself can be programmed to recognise the code sequences of a number of different keys, which means that it is possible for the car to recognise the driver and automatically adjust mirrors, seat position and driving performance accordingly.

Philips Semiconductors is developing two new systems which will use this new cryptographic system. The first is called SECTPLUS and provides the user with unlocking and locking buttons built into the car key for remote activation similar to the RF or IR systems currently available. To avoid the problems of having regularly to fit new batteries into the car key, this one has a battery that is recharged whilst within the ignition via an inductance loop. In addition, there is a regular re-synchronisation of the rolling code and a higher security level for the UHF or IR link due to the use of the crypto unit.

The second system is called Passive Entry and operates within about one and a half metres of the car. Locking is effected by simply leaving the detection zone around the car. This facility could be particularly useful when dealing with packages for example. The system can even determine the difference between passengers and the driver because there is a driver authorisation zone covering the driving seat. It could even be extended to the point where the Passive Entry chip is not built into a mechanical key but into another device, such as a watch or smartcard.

The SECT IC, the PCF79735, is available in a standard stick transponder package and is priced in the region of $2.00 in volume quantities.

Philips Semiconductors, a division of Philips Electronics NV, headquartered in Eindhoven, The Netherlands, is the eleventh largest semiconductor supplier in the world. Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs.