Abstract: The vehicular ad hoc network (VANET) improves the efficiency of road transportation and is a necessary infrastructure for future smart cities. However, the security and privacy issues faced by VANET may lead to serious traffic accidents, which makes anonymous authentication of messages necessary, while existing authentication schemes are still not a good solution to the problems of anonymous authentication, conditional privacy preservation, and authentication efficiency. In this paper, we propose a conditional privacy-preserving authentication scheme based on certificateless group signature. First, an anonymous authentication scheme based on certificateless group signature is proposed based on the combination of certificateless public key cryptosystem and ACJT group signature algorithm. In particular, when a group member changes, other group members are unaffected not needing to update the key, and the computation of the group signature generation and verification algorithm is fixed independent of the number of group members. Further, in order to prevent vehicles from committing malicious acts due to identity anonymity, the scheme realizes conditional privacy protection, i.e., when a malicious act occurs, the identity of the relevant vehicle can be traced and held responsible. Security analysis proves that the scheme can satisfy security requirements such as forward security. Performance experiments show that the scheme outperforms similar schemes in terms of authentication efficiency and communication overhead.

Key words: Vehicular ad hoc network, Elliptic curve, Certificateless, Group signature, Anonymous authentication

摘要： 车联网提高了道路交通效率，是未来智能城市的必要基础设施。然而车联网面临的安全与隐私问题可能导致严重交通事故，这使得对消息进行匿名认证成为必要，而已有认证方案仍然不能很好地解决条件隐私保护、匿名认证和认证效率等问题。本文提出了一种基于无证书群签名的车联网条件隐私保护认证方案。首先，在结合了无证书公钥密码体制和ACJT群签名算法的基础上，提出了基于无证书群签名的匿名认证方案。特别地，当群成员发生变化时，其他群成员不受影响无需更新密钥，并且群签名生成和验证算法的计算量固定，不受群成员数量影响。进一步，为防止车辆因身份匿名而做出恶意行为，方案实现了条件隐私保护，即当恶意行为发生时，可以追查相关车辆的身份并追究责任。安全分析证明该方案能够满足前向安全等安全需求。性能实验表明该方案的认证效率和通信开销都优于同类方案。

关键词: 车联网, 椭圆曲线, 无证书, 群签名, 匿名认证