Abstract: Certificateless public key cryptology does not need certificates to verify the validity of public key, and overcomes the key escrow problem in ID-based public key cryptology. By analyzing the security of a certificateless signature scheme without pairing, it was pointed out that the scheme is insecure against a malicious Key Generating Centre (KGC) attack. Then, an improved scheme was proposed, whose security was based on the Discrete Logarithm Problem (DLP).

Key words: certificateless signature, cryptanalysis, Discrete Logarithm Problem (DLP), random oracle model, existential unforgeability

摘要： 无证书公钥密码体制不需要证书对公钥进行认证，同时也克服了基于身份密码体制中存在的密钥托管问题。通过对一个没有双线性对的无证书签名方案进行了安全性分析，指出其对KGC攻击是不安全的。然后，对原方案进行了改进，改进后的方案同样没有对运算。改进方案的安全性基于离散对数困难问题。

关键词: 无证书签名, 密码学分析, 离散对数问题, 随机预言机模型, 存在性不可伪造