HERMES: Scalable, Secure, and Privacy-Enhancing Vehicle Access System

We propose HERMES, a scalable, secure, and privacy-enhancing system, which allows users to share and access vehicles. HERMES outsources the vehicle access token generation to a set of untrusted servers, utilizing several cryptographic primitives with secure multi-party computation efficiently. It conceals the vehicle secret keys and transaction details from the servers such as vehicle booking details, access token information, and user-vehicle identities. It also provides user accountability in case of disputes. We prove that HERMES meets its security and privacy requirements. Moreover, we demonstrate that HERMES scales for a large number of users and vehicles, making it practical for real-world deployments. To achieve high-performance computations, we evaluate HERMES over two different multiparty computation protocols for Boolean and arithmetic circuits. We provide a detailed comparison of their performance, together with other state-of-the-art access provision protocols. Through a proof-of-concept implementation, our performance analysis demonstrates that HERMES requires only approx 61ms for a single-vehicle access provision. At the same time, it handles 546 and 84 access token generations per second from a single-vehicle owner and large branches of rental companies with over a thousand vehicles, respectively.