AES Security Protocol Implementation for Automobile Remote Keyless System

The remote keyless system is widely used in automobile industry to lock or unlock the automobile's door, trunk, and start the ignition. It comprises a handheld key fob to be held by the driver and a set of radio transceiver devices located in the automobile. Operation commands are represented by strings of wireless signal transmitted between the key fob and the radio transceiver to realize various car operations. Because the radio signal is transmitted in proximity of open area, the remote keyless system has the possibility of exposing the key secret commands to a car thief. The operation commands which are denoted by plaintexts or even cipher texts cannot overcome this security problem. This paper proposes a new approach in which encryption of the operation commands is realized by a model of AES algorithm computed with a fixed key and a variable key. In the newly designed AES security protocol, the key fob and radio device will be engaged in the protocol interrogation after the key fob initiates a connection. The fixed key can be defined by car manufacturer or car dealer, and it is used for the encryption of handshake message and a pseudo random number (PRN). This PRN is proposed by the key fob, and will serve as the variable key. This method can effectively defeat today's common attack tricks such as brute-force key guess attack, statistics attack, masquerade attack, etc.