Cryptanalysis of group signature scheme using self-certified public keys

A group signature is a digital signature that allows a group member to sign messages anonymously on behalf of the group. Recently, Tseng and Jan propo sed a group signature scheme which uses self-certified public keys. The aut hors show that the newly proposed group signature scheme is linkable becaus e, given two signatures, it can be easily decided if both signatures are ge nerated by the same group member.