A Privacy-Preserving Authenticated Key Exchange Protocol for V2G Communications Using SSI

The popularity of Electric Vehicles (EVs) has been rising globally in recent years. With the demand for EVs, associated cyber threats are also increasing. Users expose their personal information while charging their EVs, leading to privacy threats. This paper proposes a user-empowered, privacy-aware, authenticated key exchange protocol for Vehicle-to-Grid (V2G) communications. The proposed protocol leverages the concept of Self-Sovereign Identity (SSI) and is based on the concept of Decentralized Identifiers (DID) and Verifiable Credentials (VCs). The use of DIDs empowers users by helping them to have complete control over their identities. The charging station and the user verify that the other party is legitimate by verifying the VC before proceeding with the charging services. Key recovery is another issue we address in this paper. A method to recover lost keys is incorporated into the proposed protocol. The proposed protocol also incorporates an effective user revocation policy. We present formal security proof and informal analysis to show the protocol's robustness against several attacks. We also provide a detailed performance analysis to show that the proposed protocol is efficient.