一个强安全的无证书签名方案的分析和改进

Security Analysis and Improvement of Strongly Secure Certificateless Digital Signature Scheme

无证书公钥密码体制结合了基于身份的密码体制和传统PKI公钥密码体制的优势,克服了基于身份的公钥密码体制的密钥托管问题及PKI系统的证书管理问题,具有明显的优势。对Hassouna等提出的一个强安全无证书签名方案进行安全分析。结果表明,该方案不能验证消息的完整性,存在消息篡改攻击,且方案未使用根据系统主密钥生成的私钥进行签名,所以不是无证书签名方案。在此基础上,提出了一个改进的无证书签名方案,在随机预言机模型下,基于椭圆曲线Diffie-Hellman问题假设,证明了该方案可以抵抗第一类强敌手和第二类敌手的攻击,满足存在性不可伪造的安全性。

Certificateless public key cryptosystem combines the advantages of identity-based cryptosystem and traditional PKI public key cryptosystem,overcomes the key escrow problem of identity-based public key cryptosystem and the certificate management problem of PKI system,and has obvious advantages.By analysing the security of a strongly secure certificateless signature scheme proposed by Hassouna,et al,it shows that the scheme cannot resist the attack of falsifying messages and do not use private key generated by system master key to sign.So it is not a certificateless signature scheme.On this basis,an improved certificateless signature scheme is proposed and it proves the scheme can resist the attack of the first class of strong adversaries and the second class of adversaries.In the random oracle model and under the assumption of the Diffie-Hellman problem of the elliptic curve,the improved scheme satisfies the existential forgery.