Details of Research Outputs

目前已提出的群代理签名方案存在两个问题,首先缺乏在完整的群代理签名安全模型下证明方案的安全性;其次在标准模型下的群代理签名方案没有涉及到用户身份这一概念,具有一定的使用局限性.针对上述两个问题,在Boldyreva等人提出的代理签名安全模型的基础上提出一个完整的群代理签名可证安全模型,同时为了展示该安全模型的有效性,给出一个群代理签名方案的可证安全实例.该实例通过对Paterson等人提出的标准模型下基于身份的签名方案进行扩展,提出在标准模型下基于身份的群代理签名方案,并在可证安全模型下证明新方案具有在自适应选择消息攻击下存在基于身份的群代理签名不可伪造性,其安全性在标准模型下可归约于CDH问题假定.与目前已有的标准模型下基于公钥密码体制的群代理签名方案相比,该群代理签名方案增加了用户身份的概念,同时具有更完备的可证安全性. 

Current group proxy signature schemes are not proved for their security in the complete security model for group proxy signature, and do not involve the concept of identity. In this paper, we show a complete security model for group proxy signature based on Boldyreva's security model. And a new identity-based group proxy signature scheme is proposed in the standard model based on the Paterson's scheme. In our security model for group proxy signature, the new scheme is proved to have the existential identity-based group proxy signature unforgerability under an adaptive chosen message attack, and have a security reduction to CDH problem. Compared with other group proxy signature schemes based on public key cryptosystem in the standard model, the new scheme is more secure and involves the concept of identity.