Probing Attacks on Physical Layer Key Agreement for Automotive Controller Area Networks

Efficient key management for automotive networks (CAN) is critical, governing the adoption of security in the next generation of vehicles. A recent promising approach for dynamic key agreement between groups of nodes, Plug-and-Secure for CAN, has been demonstrated to be information theoretically secure based on the physical properties of the CAN bus. In this paper, we illustrate side-channel attacks on the scheme, leading to nearly-complete leakage of the derived secret key bits to an adversary that is capable of probing the CAN bus. We identify the fundamental network properties that lead to such attacks and propose ideas to minimize the information leakage at the hardware, controller and system levels.