Physical layer security based on timing and voltage features for controller area networks

Abstract

Since Controller Area Network (CAN) buses used in vehicles are exposed to certain threats that are described in research works and exploited in real-world conditions, certain updates with emphasis on its security are required. The thesis includes an overview of the CAN vulnerabilities as well as research proposals for their mitigation through physical layer security using timing and voltage characteristics. An innovative key-exchange method that makes use of CAN messages and the CAN protocol requirements for exchanging session keys between nodes is presented as part of the thesis. An improvement for a previous work related to time-covert authentication methods by optimizing the frame transmission times is also discussed in the thesis. From a hardware standpoint, there are certain research papers that use clock skews for periodic CAN messages as fingerprints for transmitter authentication. Other works use the unique voltage characteristics for both periodic and on-event CAN messages as fingerprints for the senders. The thesis includes a broad comparison of the reliability of clock skews and voltage characteristics as fingerprint sources from 9 passenger vehicles. The analysis is done on a public dataset of both frame timestamps used for clock skew derivation and voltage samples used for extraction of unique voltage characteristics for each node. Considering that realistic CAN architectures need to be realized as experimental setups, a digital twin for a real-world vehicle CAN network is described in the later part of the thesis. Considering the noise factor in voltage fingerprinting activities, an analysis of the wiring influence from the digital twin experimental setup with other setups and the real-world vehicle conditions is also presented in the thesis.