The existing privacy-preserving authentication models for Vehicular Ad-hoc Networks (VANETs) primarily preserve multiple pseudonyms for one vehicle, while overlooking the consideration of confidential identity requirements. These authentication models cause pseudonyms management complex and revocation inconvenient. Blockchain seems to be suitable for storing the pseudonym certificates as transactions in the ledger, which enables distributed authentication. However, blockchain produces high latency for the membership verification of users. To tackle these problems, we present an Efficient Privacy-preserving Authentication Model (EPAM), leveraging the asynchronous accumulator to extend the blockchain application. The asynchronous accumulator supports efficient membership verification and avoids the time consuming of checking the Certificate Revocation List (CRL). Additionally, by designing a mutual authentication protocol, we achieve privacy properties such as anonymity and unlinkability under the consideration of the semi-trust RSUs. The simulations show that the membership verification time is about 0.157ms in EPAM test over $10^7$ certificates, thus alleviating the mutual authentication latency in VANETs.

现有的用于车辆自组织网络（VANET）的隐私保护身份验证模型主要为一辆车辆保留多个假名，同时忽略了对机密身份要求的考虑。这些认证模型导致假名管理复杂并且撤销不便。区块链似乎适合将假名证书作为交易存储在分类账中，从而可以进行分布式身份验证。但是，区块链为用户的成员身份验证产生了高延迟。为了解决这些问题，我们提出了一种有效的隐私保护身份验证模型（EPAM），利用异步累加器扩展了区块链应用程序。异步累加器支持有效的成员身份验证，并避免了检查证书吊销列表（CRL）的时间。此外，通过设计双向身份验证协议，我们在考虑半信任RSU的情况下实现了诸如匿名性和不可链接性之类的隐私属性。仿真结果表明，在EPAM测试中，隶属验证时间约为0.157ms。$\mathrm{1个}{0}^7$ 证书，从而减轻了VANET中的相互身份验证延迟。