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.

I. Introduction

Over the past few years, electric vehicles (EVs) have gained considerable interest and brought unprecedented opportunities and challenges for our daily lives, while playing an important role in bringing convenience and reducing pollution in transportation areas. In the US, the average cost to fuel a vehicle with a regular-grade gasoline is $2.85 while the cost of an electric eGallon is$1.16, and a single EV will produce annually an average of 3,774 pounds of CO2 equivalent compared to 11,435 pounds produced by a conventional gasoline vehicle [1]. Compared with gasoline vehicles, EVs are more economical and environmentally friendly owing to the cheaper electricity price and reduced greenhouse gas emissions [2], which are expected to take a prominent role in the future transportation system. Meanwhile, with the rapid development and expansion of EV industry and market in recent years, more and more charging stations and the corresponding infrastructures need to be deployed in order to satisfy the huge demand for charging of EVs. According to the Internation Energy Agency (IEA), the share of EVs in the global automobile market will surge from only 3 currently to 12 by 2030 [3]. There is also a prediction that the number of EVs in use is expected to grow from 3 million to 125 million by 2030 [4]. EVs are seen as an important component for the future intelligent energy grid [5]. Therefore, it has become increasingly crucial to provide better charging services while efficiently promoting the corresponding technology development.