一种不可否认的门限代理签名方案

针对目前的门限代理签名方案计算复杂性高、通信量大的问题，提出一种不可否认的门限代理签名方案.为提高安全性，在签名人向CA申请公钥证书时，CA采用零知识证明的方法对与该公钥相关的私钥进行验证，保证该公钥未被篡改.为提高运行效率，代理份额产生阶段，原始签名人只需计算一个公共的代理份额，广播给代理群，各个群成员并行地生成自己的代理密钥，与原始签名人逐一为每个代理群成员生成代理密钥的串行操作相比，减少了计算量.采用将敌手分为三类的安全模型，仿真各类敌手伪造签名的过程，证明方案的安全性.

A Kind of Threshold Proxy Signature Scheme with Nonrepudiation Property

To overcome the drawbacks， such as high computational complexity and heavy communication， in the present threshold proxy signature schemes， a nonrepudiable threshold proxy signature scheme was proposed. To improve the security，when a signer applies for public key certificate to the CA， the CA validates the signer′s private key associated with the signer′s public key by the method of zero-knowledge proof. To improve the efficiency， in the phase of proxy key generation， original signer only needs to calculate and broadcast a public proxy share to the proxy group， and the group members generate their own proxy keys concurrently. Comparing with the schemes that original signer generates proxy keys one by one for all the proxy members， the amount of calculation was greatly reduced by the proposed method. The security model of three types of adversaries was proposed. It was simulated that the adversaries forge the signature. The new scheme was proved to be secure by the simulation process.