对一个无证书签密方案的分析与改进

摘要

He 对 Liu 等人提出的无证书签密方案进行了改进，用以实现 AⅠ类型敌手攻击下签密方案的不可伪造性。但通过对 He 所提的改进方案进行安全性分析发现，该方案无法抵制 AⅡ类型敌手的伪造签密攻击，并且用户在签密过程中使用的一次性数据一旦发生泄露也会影响方案的安全性。由此，基于椭圆曲线离散对数问题提出一个新的无证书签密方案，安全性及效率分析表明新方案能弥补 He 所提方案存在的安全漏洞且运行效率不低于同类方案。%To realize unforgeability of signcryption scheme under AⅠ’s attack,He Debiao proposed an improvement of a cer-tificateless signcryption scheme presented by Liu,et al.Security analysis indicated that He’s scheme could not resist AⅡ’s attack,and it was also not secure when revealed the one-off data used in signcryption.To solve the security problem existed in He’s scheme,this paper developed a novel certificateless signcryption scheme based on elliptic curve discrete logarithm prob-lem.Analysis shows that new scheme is more secure than He’s and no less efficient than schemes of same kind.