A Blockchain-Based Conditional Anonymous Authentication Scheme
Sen Wang, Yin Zhang, Ling Zhu Xiong · 2023
In recent years, the security of industrial systems has received high attention. Once a problem occurs, it is necessary to trace back the user access records to investigate the issue. Blockchain-based identity verification schemes have been applied to authentication phase. However, due to the public and transparent nature of the blockchain, it may expose users’ information and raise a series of privacy concerns. Unlinkable anonymous authentication technology can provide reliable privacy protection for these blockchain-based solutions. However, it is also necessary to track malicious users under some condition. Inspired by this, this article proposes a blockchain-based conditional anonymous scheme (BTAS) for saving access records. In the proposed scheme, a trusted third party first uses PS signature to generate credentials for users. Every time the user accesses the server, the credential is randomized and non-interactive zero-knowledge technology is used to prove the user’s identity, achieving the goals of anonymous authentication and unlinkability. At the same time, taking advantage of the characteristics of blockchain’s public verification and immutability, the server uploads the access records of authenticated users to the blockchain for later issue troubleshooting. In addition, the proposed scheme uses distributed ElGamal algorithm to achieve traceability, avoiding the risk of malicious users compromising the security and stability of the scheme under anonymity. Through security analysis, it has been proven that this scheme has advantages such as anonymity, unlinkability, non-forgeability, and traceability. Experimental results show that compared with other anonymous authentication schemes, our scheme has better performance.