对一种指定接收组的强代理签名方案的分析与改进

在分析了陈春华，徐秋亮（2007）提出的一个基于HHW方案]的具有指定接收组特性的方案之后指出，这个方案的签名验证数据中没有回避孤悬因子，因此不具备强不可伪造性，即原始签名人可以伪造一个有效的代理签名通过验证，并成功地在代理签名人身份揭示阶段向公众证明该伪造的代理签名是由合法的代理签名人生成的．在分析该方案安全性的基础上提出了改进的方案．改进后的方案可以抵抗原始签名人的伪造攻击，具有强不可伪造性．

Cryptanalysis and Improvement of A Designed Group-receiver Strong Signature Scheme

With the analysis of the signature scheme, ＂A Designed Group-receiver Strong Proxy Signature Scheme＂, which was put forward by Chen-Xu （2007）, the paper points out that it does not posses the strong unforgeability property because of not being able to avoid the suspending-factor. That is, the original signer can forge a valid proxy signature and pass the procedure of verification and revelation,therefore he or she can successfully prove it is signed by a legal proxy signer. Based on the analysis of the Chen-Xu＇s scheme, the paper proposes an improvement of the proxy signature scheme. The security analysis shows that it can resists the forgery attacks and retains some merits of the original scheme. It possesses the strong unforgeability property.