Although demonstrated to be effective, the fixed code did not meet the requirements of future systems. As a result, today's second generation car immobilizer systems are equipped with copy protection techniques, to reduce fraud and professional car theft. More than 100 million transponders from Philips Semiconductors are currently protecting vehicles worldwide. Embedded in the car key, the transponders communicate via a radio frequency link with the engine management electronics, without requiring a battery. These immobilizers prevent the engine starting without authorisation, even making it impossible to short-circuit the system.
Authorisation is given at the same time as the driver turns the key in the ignition.
And the latest systems use challenge response and mutual authentication algorithms designed to prevent transponders being duplicated. Products Philips Semiconductors has a complete family of immobilizer products, including transponders and matching vehicle basestations, to fulfil all customer needs. All transponders are produced in a stress resistant plastic package, invented by Philips Semiconductors, which has become the industry standard. However a significantly higher security level can be achieved by providing a re-writeable memory area, as with the PCF7930 . This enables the customer to implement code hopping algorithms which changes the code in the transponder every time the engine is started.