Secure asymmetric algorithm for remote car locking

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Research scientists at the Fraunhofer Institute for Secure Information Technology in Garching have developed an asymmetric algorithm to provide a more secure remote locking systems for cars.

While remote central locking is prized for its convenience, transmission of the radio signal that activates the system is not particularly secure. With existing key codes, a car thief can use an antenna to eavesdrop on the radio signal and create a second key from the captured data. The reason for this security flaw is that the algorithms which encrypt the signals sent from the key to the vehicle are not strong enough, and the code was broken about two years ago.

Car manufacturers are therefore using new algorithms to make the radio key systems more secure. But these algorithms have a major disadvantage: they are symmetric, meaning the codes are embedded in the key and in the car. Also, the same coded information is embedded in many vehicles from the same production line. Once one code has been broken, numerous cars are at risk.

With the asymmetric algorithm developed at Garching the code is resident only in the car key, and not in the car as well, says researcher Johann Heyszl. “Each car key incorporates a different code, and this makes the encryption much more secure than when a symmetric algorithm is used.”

Previously the high computation intensity and associated high energy consumption meant it was not possible to use asymmetric algorithms in car keys. ”We have built a small cryptographic chip which is particularly energy-saving. In addition, we have developed a new, efficient protocol which minimises computation effort and the amount of data that has to be transmitted,” Heyszl said. As a result, the battery life of the key is about the same as in symmetric encryption, but the new system is much more secure. The electronic immobilizer is encrypted in the same way as remote central locking.

The researchers have developed a functioning prototype and will be presenting the system at the Embedded World trade show from March 2 to 4 in Nuremberg (Hall 11, Stand 11-101).