【摘要】 对两个高效的无证书签名方案进行了安全性分析,证明了这两个方案都是不安全的。对于第一个方案,类型Ⅰ敌手可以利用公钥替换伪造任何用户对任意消息的签名。对于第二个方案,它不仅在类型I敌手攻击下不安全,而且在类型Ⅱ敌手攻击下也不安全。类型Ⅱ敌手即恶意KGC可在系统参数生成阶段利用预选目标用户的身份生成含有陷门信息的系统参数,然后计算该目标用户的私钥并伪造对任意消息的签名。更多还原

【Abstract】 This paper analyzed two efficient certificateless signature schemes.It indicated that the two schemes were insecure.For the first scheme,a Type I adversary could forge a valid signature for any message of any user by substituting the target user’s public key.For the other scheme,it was vulnerable against both Type I and Type Ⅱ adversaries.After generating the trapdoor system parameters according to the identity information of a pre-selected target user,the Type II adversary(malicious private key generator) was able to compute the user’s private key and forge a signature on any message of the user.更多还原