强安全无证书签名方案的安全性分析和改进

对王亚飞等人提出的强安全性无证书签名方案进行安全性分析，指出其方案难以抵抗不诚实KGC下的公钥替换攻击。针对此类问题，采用改变传统无证书算法顺序，以KGC公告板形式公开用户公钥，用户可以通过本地保存的私钥和公钥验证公钥的真实性，从而对KGC的行为进行约束。安全性分析表明，改进后的方案能够抵抗基于不诚实 KGC安全级别下的公钥替换攻击，而且方案避开了无双线性对和逆运算，效率优于已有方案。

Security analysis and improvement of strongly secure certificate less signature scheme

By analyzing the security of strongly secure certificateless signature scheme proposed by Wang Yafei et al, the problem that the scheme could not resist public key replacement attack under dishonest KGC was pointed out. Aiming at this problem, the behavior of KGC was restrained by the change of traditional certificateless algorithm sequence KGC bulletin board where user public key make public, and verifiability of facticity of public key through the local private keys and public keys. The analysis of security shows that the improved scheme cannot only resist the public key replacement attack based on dishonest KGC, but also be more efficient than the existing schemes for avoiding pairings and inverse operation.