Priority-based and privacy-preserving electric vehicle dynamic charging system with divisible E-payment

Dynamic charging systems enable moving electric vehicles (EVs) to charge using magnetic induction from charging pads (CPs) installed on roads. For the system to function, the EVs need to communicate with the various entities of the system, which include a bank, a charging service provider (CSP), roadside units (RSUs), and CPs. This communication should not reveal sensitive location information about the EV drivers, and security should also be thoroughly investigated to ensure proper operation of the system. In this chapter, we present a scheme that provides integrated, secure, and privacy-preserving authentication, prioritization, and payment for dynamic charging. In order to make payment, the EV should first purchase divisible e-coins from the bank and use them when it needs to charge. The payment scheme should be efficient and flexible in that the value of the e-coins can be adjusted based on the amount paid for charging. Charge prioritization is needed when the energy supply is less than the charging demand because the CSP cannot serve all incoming charge requests. In our scheme, a priority policy is determined by each charging station, and a multiauthority, attribute-based encryption scheme is used to ensure the security and privacy of the policy. In order to address the scalability of the system due to the large number of EVs and CPs and the limited resources of the CPs, an efficient hierarchical authentication scheme that is based on symmetric-key cryptography is proposed. The idea is that after an EV authenticates successfully to the CSP, it receives secret keys, called tokens, that are shared with the RSUs. After using these tokens to authenticate to the RSUs, the EV receives secret tokens that are shared with a number of CPs under each RSU control. These tokens are used to enable the CPs to identify and charge only authorized EVs. Our security analysis demonstrates that the proposed scheme is secure and can preserve the privacy of the EV drivers by making identifying the drivers and tracing them infeasible. In addition, performance evaluations confirm that the computational and communication overhead of the scheme is acceptable.