MUNICH, Germany — Radio-controlled entry systems are ubiquitous in today's cars, but security remains an issue. Fraunhofer Scientists now for the first time have implemented an asymmetric encryption scheme in a car key. They claim that the hardware required is comparable in price and power requirements to conventional symmetric encryption keys.

Conventional, i.e. symmetric encryption schemes can be easily eavesdropped. Depending on the key length, it takes varying but relatively low efforts to crack the key, as has been proved in the case of the Keeloq scheme or NXPs Mifare system. Asymmetric encryption schemes which use a pair of public and private keys are said to be much more secure. However, they also require a much more powerful hardware which is one of the reasons they hitherto have not been implemented in keyless entry systems.

Another virtue of asymmetric systems is that the control circuitry within the vehicle only needs to "know" the less complex public key. This is beneficial during the final stage of the production when electronic parameters are downloaded ("flashed") to the cars.

The Fraunhofer Institute for Secure IT (Garching, Germany) claims it has implemented an asymmetric algorithm on a hardware suited for car key systems. "Hitherto, the high computing power required prevented the industry from using asymmetric encryption", explained Fraunhofer scientist Johann Heyszl. "High computing power normally is associated with high electric power consumption which made it difficult to implement such a solution as a car key with a small battery."

According to Heyszl, the researchers have implemented a chip that runs an elliptic curve cryptography algorithm at very low power consumption. The device makes use of a new protocol that helps to reduce the power consumption without sacrificing security, Heyszl claims. While the researcher declined to specify the key length used for the prototype, he said that in commercial implementations it is variable and could be adjusted to the needs of the respective customer. Thus, remote entry system designers can maintain their edge over crackers who dispose of increasing computer power for their attempts to compromise such systems.