一个群签名方案的密码学分析与改进

Cryptanalysis and Improvement of a Group Signature Scheme

最近,陈泽文等人提出了一种基于中国剩余定理的群签名方案,该方案的安全性是基于大数分解困难性假设.本文对该群签名方案进行了分析,指出该方案中的大数分解可有效地进行计算,其安全性假设是不合适的,该方案所描述的诸多优越性实质上并不存在.文章同时给出了一个改进方案,在强RSA假设下,改进的方案不仅弥补了原方案的安全缺陷,而且改善了协议的性能.

This paper analyzes the security of a group signature scheme based on Chinese Remainder Theorem proposed by Chen-ZW recently. The security of Chen-ZW＇ s scheme relies on the assumption of integer factorization, but it is computable to factor the large integer in the scheme because all the group members share a same RSA modulus n. Therefore, the security assumption is unsuitable for the scheme, and the advantage of the scheme is virtually nonexistent. The paper also gives a modified scheme, which elaborately eliminates the defect of the original scheme and improves the efficiency of the protocol.