中文摘要：

首先,提出具有代理解签密功能的签密概念.此模型中,原始解签密者把消息分为不同的主题,按照主题把解密权力授予不同的代理人;代理人可以代替原始解签密者解密其授权主题下的密文.其次,给出安全模型并基于无证书公钥密码体制提出一个具体方案.最后,基于Weak-BDH难题证明该方案的安全性.

英文摘要：

Firstly,this paper gives a new signcryption model,named signcryption with proxy unsigncryption.In this model,the original unsigncrypter divides messages into several subjects and delegates his unsigncryption powers to different proxies.The authorized proxies can directly unsigncrypt ciphertexts for the original unsigncrypter.Secondly,this paper gives the security model and based on certificateless public key cryptography give a concrete scheme.At last,this paper proves its security based on Weak-BDH problem.