Security Mechanism for Digital Car Key

The digital car key enhances the convenience of the users. However, the security of wireless communication is at risk. This paper designs and builds a digital car key system, including the vehicle, the server, and the mobile device. Then an attack-defense tree model is used to analyze the security risk and countermeasures. The designed security mechanism includes the RSA algorithm, AES algorithm, freshness check, and key distribution and transmission. It also considers the real-time requirements of the automotive embedded system and uses the hardware-based security module. The system can resist tampering attacks, replay attacks, man-in-the-middle (MITM) attacks, etc. Finally, a MITM attack is implemented to test the security mechanism.