无双线性对的无证书签密方案分析与改进

对高键鑫等人提出的一种无双线性对运算的无证书签密方案进行密码分析,指出方案的不可伪造性证明存在漏洞,致使方案不安全,并提出了一个改进的签密方案.安全性能方面,为了抵抗不诚实用户发起的公钥替换攻击,改进方案在签密运算的指数部分加入用户生成的部分公钥的哈希函数值,并在随机预言模型下证明了改进方案对自适应选择消息和身份攻击是存在性不可伪造的,改进方案没有使用计算耗时的对运算,具有较高的运算效率.

Analysis and Improvement of a ID-based Signcryption Scheme

A certificateless signcryption scheme without bilinear pairing which proposed by Gao Jianxin et al. was analyzed. It was pointed that there was the error in the proof process of unforgeability,which leads to the insecure of the scheme. Therefore,an improved signcryption scheme was proposed. In terms of safety performance,the hash value of the partial public key generated by users was embedded into the index part of signcryption operations,as a result,the improved scheme can effectively resist public key replacement attacks. Moreover,in terms of computational cost,the improved scheme still has the high computing efficiency because of not using bilinear pairing.