Abstract: All of the existing threshold group signature schemes have weaknesses.The design of an efficient scheme is remained open in cryptography.The weaknesses of a dynamic threshold group scheme are analyzed.The most serious weakness is that part of members can conspire to get system secret parameters and then forge a valid signature.

Key words: cryptography, group signature, threshold group signature, conspiracy attack

摘要： 已有的门限群签名方案几乎都存在弱点,设计性能良好的门限群签名是密码学中的一个公开问题。针对一种动态门限群签名方案详细分析了其存在的弱点,其中最主要的弱点是:部分成员可以合谋得到系统的秘密参数,从而伪造群签名。

关键词: 密码学, 群签名, 门限群签名, 合谋攻击