两种无证书聚合签名方案的安全性分析及改进

大部分的聚合签名方案存在安全性缺陷和计算效率偏低的问题。通过对两种无证书聚合签名方案进行安全性分析,发现两种方案分别无法抵抗Type I和TypeⅡ的伪造性攻击。针对此类问题,提出了一个改进方案。该方案在签名过程中改变了参数的组合方式,在聚合签名验证中加强了对主密钥和公钥的约束。在计算性Diffie-Hellman困难问题假设下,证明了方案在适应性选择消息攻击下具有不可伪造性。效率分析表明,方案在签名与验证过程中只需要4个双线性对运算,签名的长度是固定的,与同类安全的无证书聚合签名方案相比,改进的方案效率更高。

Security analysis and improvement of two certificateless aggregate signature schemes

The security flaws and low computational efficiency problem exist in most of the aggregate signature schemes. Based on the security analysis of two kinds of certificateless aggregate signature scheme, it is found that the two schemes can not resist forgery attack under Type I and Type II. Aiming at this sort of problems, we proposed an improved scheme that has changed the combination mode of parameters in the process of signature and has strengthened the constraints of master key and the public key in the process of aggregate signature verification. It was proved that the prosed scheme is existentially unforgeable against adaptive chosen message attacks under the computational Diffie-Hellman assumption in the random oracle model. The efficiency analysis shows that the scheme needs only 4 bilinear pairing operations in the signature process and the verification process, and the length of the signature is fixed. This improved scheme is more efficient comparing with the other certificateless aggregate signature schemes in similar secure level.