群签名是对一般数字签名的一种扩展, 有很多重要应用. 最近提
出的一种高效的群签名, 被声称没有采用知识签名, 从而签名和验证的计算
量远远少于著名的ACJT 方案. 在本文中, 我们指出该方案其实采用了知识
签名, 但是由于使用上的不当, 使得该方案完全不安全, 即两个群成员合谋
就可以伪造出对任意消息的群签名, 且打开算法是无效的.

Group signature schemes are extended from ordinary digital
signatures motivated by many applications. Zhang et al. proposed an e±-
cient group signature scheme which was claimed more e±cient than the well
known ACJT scheme, due to the reason that expensive signature of knowl-
edge, a component in a majority of group signature schemes, was avoid in
generating the group signature. In this paper, we point out that Zhang et
al.’s scheme actually adopts signature of knowledge, and it is insecure com-
pletely because of inappropriate design.