Vehicular ad hoc networks (VANETs) promise to enhance transport efficiency, passenger safety, and comfort through the exchange of traffic and infotainment information to vehicles. The acceptance of VANET hinges on the correctness and timeliness of messages and assurance of an individual’s safety through privacy protection. The message accuracy requires the authentication of vehicles. This translates into the requirement of an efficient privacy-preserving authentication mechanism along with the need for privacy and time-bound delivery of messages. The security and privacy issues must be addressed primarily in the communication protocol’s design. Different privacy-preserving authentication schemes have been proposed to ensure the correctness of messages during vehicular communications. However, most of the schemes do not entirely solve the issues related to security and privacy, threats and vulnerabilities, communication, and computation costs. In this survey, we focus on cryptographic techniques proposed to achieve authentication, privacy, and other security features required in VANETs like symmetric key cryptography-based schemes, public key cryptography-based schemes, identity-based cryptography schemes, pseudonym-based schemes, group and ring signature-based schemes, and blockchain-based schemes. We provide a comprehensive study of schemes with their classifications, strengths, and weaknesses. The study reveals that most of the existing authentication schemes require trusted authorities that are opaque in their functioning, certificate revocation requires heavy computation and storage along with a large amount of lookup time. The computation and communication overhead required for authentication is significant, which drastically affects the timely delivery of messages. More work is needed for the development of lightweight and efficient privacy-preserving authentication schemes in VANETs.

车辆自组织网络 (VANET) 承诺通过与车辆交换交通和信息娱乐信息来提高运输效率、乘客安全和舒适度。VANET 的接受取决于消息的正确性和及时性以及通过隐私保护确保个人安全。消息的准确性需要对车辆进行身份验证。这转化为对有效的隐私保护身份验证机制的需求以及对隐私和限时消息传递的需求。安全和隐私问题必须主要在通信协议的设计中解决。已经提出了不同的隐私保护认证方案来确保车辆通信过程中消息的正确性。然而，大多数方案并没有完全解决与安全和隐私、威胁和漏洞、通信和计算成本相关的问题。在本次调查中，我们重点关注为实现 VANET 所需的身份验证、隐私和其他安全特性而提出的加密技术，如基于对称密钥加密的方案、基于公钥加密的方案、基于身份的加密方案、基于假名的方案、组基于环签名的方案和基于区块链的方案。我们对计划的分类、优势和劣势进行了全面的研究。研究表明，大多数现有的身份验证方案都需要在其功能上不透明的可信机构，证书撤销需要大量计算和存储以及大量查找时间。身份验证所需的计算和通信开销很大，这极大地影响了消息的及时传递。在 VANET 中开发轻量级和高效的隐私保护认证方案需要更多的工作。