Forgery Attacks on a Series Group Signature Schemes
对一类群签名方案的伪造攻击

Two kinds of forgery attacks strategy on the group signature schemes proposed respectively by Wang et al.. (2003) and Lin et al.. (2006) based on the Tseng-Jan’s(1999) group signature scheme is developed. Without using any secret identification or secret key, anyone can forgery a valid group member certificate and then generate a valid group signature using the forged certificate only through selecting some random parameters and changing the calculation procedures. Moreover, this kind of forgery attacks strategy can be used in Lee-Chang’s (1998) group signature scheme, Tseng-Jan’s group signature scheme and their varietals’. It means this series of group signature schemes is insecure.