Abstract: This paper analyses the security of two certificateless signcryption schemes, which all can’t guarantee security. The first certificateless signcryption scheme exists forged attack, which can pass through the proving equation. In addition, the second scheme doesn’t completely satisfy the public verification. Based on these problems, this paper proposes a new certificateless signcryption scheme and analyses the accuracy and safety of this new scheme, which is proved to be safe and guarantees the secrecy and authentication of information.

Key words: signcryption, certificateless, bilinear map, discrete logarithm problem

摘要： 对两种无证书签密方案进行了安全性分析，发现两种方案均是不安全的。第一种无证书签密方案不满足不可伪造性，第二种无证书签密方案不能完全满足公开验证性。针对这种情况，提出了一种新的无证书签密方案，同时对新方案进行了正确性分析和安全分析，结果表明新方案是安全的，真正做到了信息方面的保密性和认证性。

关键词: 签密, 证书, 双线性映射, 离散对数问题