Shanghai UEAC Exhibition Services Co., Ltd.
In this paper, the authors show that ACJT group signature scheme is insecure. The attack introduced in the paper will be helpful for researching group signature schemes in the future. Incidently, the fair E-cash system directly based on ACJT fails. But it seems that the attack does not apply to the extensions of ACJT proposed in. The extension proposed in appears to resist the attack at the cost of the presence of a trusted third party.