MTDCAP: Moving Target Defense-Based CAN Authentication Protocol

The convenience behind modern intelligent vehicles is simply that a group of intelligent electronic control units (ECUs) connected to controller area network (CAN) work in concert. However, quite a lot of studies have shown their security concerns about CAN. In this era of rampant cyberattacks, due to the broadcast mechanism of CAN and the lack of necessary security mechanisms such as encryption and authentication, ECUs are easily disturbed by various cyberattacks, thus leading to vehicle failures. To solve this problem, we propose a novel security authentication protocol based on the core concept of moving target defense, namely MTDCAP, which utilizes MaskedID and hash chains to maintain anonymity externally and ensure the authentication of the sender internally. Unlike general hash chain-based authentication, our protocol creatively incorporates a self-renewal mechanism into the hash chain, which effectively reduces the time overhead and security risk of negotiating the update of the hash chain between both communicating parties. In addition, AES serves to encrypt CAN message payload so as to prevent adversaries from eavesdropping. The theoretical analysis for the security against four kinds of attacks (i.e., eavesdropping, impersonation, replay, and bus-off attacks) in MTDCAP is detailed. Afterwards, a series of protocol evaluations are conducted on two kinds of typical hardware platforms, including T-Box from real vehicle supported by XPeng, and the results reveal that the proposed protocol significantly outperforms the existing protocols in the robustness, bus load, and time overhead. In particular, the authentication overhead on T-Box is only 0.18 ms for MTDCAP.