Physical layer group key agreement for automotive controller area networks

Abstract

Distribution of cryptographic keys between devices communicating over a publicly accessible medium is an important component of secure design for networked systems. In this paper, we consider the problem of group key exchange between Electronic Control Units (ECUs) connected to the Controller Area Network (CAN) within an automobile. Typically, existing solutions map schemes defined for traditional network systems to the CAN. Our contribution is to utilize physical properties of the CAN bus to generate group keys. We demonstrate that pairwise interaction between ECUs over the CAN bus can be used to efficiently derive group keys in both authenticated and non-authenticated scenarios. We illustrate the efficiency and security properties of the proposed protocols. The scalability and security properties of our scheme are similar to multi-party extensions of Diffie-Hellman protocol, without the computational overhead of group operations.