一种门限签密方案的分析与改进

摘要

Through the cryptanalysis of a generalized group-oriented threshold signcryption scheme, it is found that the scheme can not resist conspiracy attack, and KDC can forge valid threshold signcryption at random. It is not provided with semantic security. The third party can decrypt signcryption. An improved scheme is proposed, which overcomes the security drawbacks and retains the merits of the original scheme.%对一种面向群组通信的通用门限签密方案(P-L-L方案)进行密码分析,发现该方案容易遭受合谋攻击,并且密钥分配中心可以任意伪造有效的门限签密,不具有语义安全性.提出了一种改进方案,新方案克服了P-L-L方案的安全漏洞,可以有效抵抗合谋攻击和伪造攻击.