Controller area network (CAN) technology is widely adopted in vehicles, but attention has been drawn recently to its lack of security mechanisms. Numerous countermeasures have been proposed, but none can be regarded as a generic solution, in part because all the proposed countermeasures require extensive modifications to existing in-vehicle systems.
To arrive at a solution to this problem, we propose a new method of protecting CAN without the need to modify existing systems. In this paper, we explain the principle of our proposed method and the architecture of the electronic control unit (ECU) that implements it. We report the result of our experiments and show its efficacy against typical security threats faced by CAN.