一种匿名代理签名方案的标记

Fu-Kou-Xiao提出了一种匿名代理签名方案，其特点在于：用户的真实身份隐藏在原始签名人颁发的一个假名中；匿名性撤销时不需要可信第3方的参与.对该方案进行分析发现，原始签名人可以滥用代理授权，代理签名人也能够对自己所生成的有效代理签名进行事后否认,即不满足代理签名权力的不可滥用性和不可否认性.

Remarks on a Proxy Signature with Proxy Signer Privacy Protection

A proxy signature with proxy signer privacy protection is proposed by Fu-Kou-Xiao,which has two characteristics listed as follows:the proxy signer's identity is hidden behind an alias;the anonymity can be revoked when it is need to identify the proxy signer without a trusted third party.In this paper,the authors show that Fu-Kou-Xiao's scheme is insecure.The original signer may use the capability of proxy signature freely.Also the proxy signer can repudiate a valid proxy signature generated by himself.Therefore,the scheme does not satisfy the properties of undeniable and misuse of the proxy signature.