群签名中成员撤销问题解决方案

针对Camenisch-Stadler群签名方案中无法撤销成员的问题，提出了一种有效的群成员撤销方案，该方案可以灵活地增加和撤销群成员。当成员加入时，群主管向其颁发成员证书，其他成员无需更新成员密钥和证书；当成员撤销时，群主管只需将撤销成员的匿名身份更新到撤销列表中，无需更新群密钥和其他成员证书，且签名长度与验证工作量均独立于群成员和已撤销成员的个数。因此，新方案适用于群成员数较多和成员更新比较频繁的群签名。

New solution scheme for the member revocation in group signature

In order to solve the problem that Camenisch-Stadler's group signature scheme could not revoke members,a new revocation scheme based on the Camenisch-Stadler's group scheme was proposed,allowing the group manager to add new members or revoke old members flexibly and freely.When a member joins the group,the group manager issues member certificate to him (her),and other members need not update the key and certificate; when a member is revoked,the group manager only adds the anonymous identity to revocation list,and other members need not update the key and certificate either.Furthermore,the length of the signature and the computational effort are independent of the number of the group members and the revoked members,so the new scheme is more suitable for large group and the group with members' heavy updates.