一个群组验证的多策略门限数字签名方案

多策略门限数字签名方案是数字签名中比较实用的一种签名方式，它能根据所签文件的安全等级选择不同的门限值群组成员集合完成签名. 目前的多策略门限数字签名方案无法解决群组验证的问题. 针对这一问题，提出了一个门限群组验证的多策略门限数字签名方案. 该方案具有多策略门限签名方案的特性，能够实现门限群组验证并能够追踪签名集合；在验证过程中，能够根据文件的安全等级选择不同门限值的群组验证成员集合来验证签名；签名群组和验证群组能够实现角色互换，从而实现双向签名. 经过安全分析，该方案是安全的、实用的.

A Multi-Policies Threshold Signature Scheme with Group Verifiability

The multi-policies threshold signature is very practical in the research of signature.In this kind of scheme,multiple secret keys are shared among a group of users,and each secret key has its specific threshold value.Moreover,the secret keys corresponding to different threshold values can be used to sign documents depending on their significance.However,all current multi-polices threshold signature schemes cannot deal with the group verifiability.In order to solve this problem,a group-verifiable multi-polices threshold signature scheme is proposed in this paper.In the presented scheme,the group verifiability can be realized and the property of the traceable multi-polices threshold signature keeps unchanged.Namely,not only the threshold values of the signing group but also the threshold values of the verifiable group can change with the secure classifications of the signing documents.In the process of verifiability,the threshold values of the verifiable group depend on the significance of the documents.The main merit is that the signing group and the verifiable group can swap their roles.Therefore,the two groups can sign and verify each other,i.e.,it is a two-way signing and verifying scheme.The analysis shows that the proposed scheme is also secure and practical.