BlockPPA: Blockchain-Assisted Privacy-Preserving Authentication for Cross-Domain Electric Vehicle Charging

Electric vehicles (EVs) bring convenience to public transport while having the potential to increase energy efficiency. With the rapid growth of the number of EVs, cross-domain charging will become a strong demand. Despite massive research on EV charging, existing schemes can hardly meet the security requirements of privacy protection and access control for cross-domain scenarios. Meanwhile, centralized methods bring the single point of failure and data modification. The problem of designing a secure cross-domain EV charging scheme to simultaneously ensure decentralization, privacy and access control has not been studied and remains open. Therefore, in this paper, we design BlockPPA, the first blockchain-assisted privacy-preserving authentication scheme for cross-domain EV charging in order to achieve this purpose. Our scheme makes each EV obtain an attribute-based secret key, which is used to authenticate itself and also anonymously illustrate that it really satisfies a designated access policy when cross-domain authentication happens. Only authorized EVs satisfying the policy do they have the ability to charge. We design three smart contracts and exploit Fabric blockchain to record the domain's detailed information and the authentication record of each cross-domain access from an EV, while achieving the decentralized verification of an authentication request. The results of security and performance analysis show the feasibility and effectiveness of the proposed cross-domain authentication mechanism.