一种改进的无可信中心的自认证多代理签密方案

AN IMPROVED SELF-CERTIFIED MULTI-PROXY SIGNCRYPTION SCHEME WITHOUT TRUSTWORTHY SYSTEM AUTHORITY

针对一种无可信中心的自认证多代理签密方案进行攻击,指出原方案中签密组内成员可以利用自身掌握的信息伪造出合法新消息,从而不具有其声称的不可伪造性。接着提出新的改进方法,利用有限域上离散对数问题的难解性,在会话加密过程中加入发送者私有数据。除了原方案一些安全特性外,经过分析,新方案具有不可伪造性、抗滥用性和不可否认性等优点。

By making the attacks on a self-certified multi-proxy signcryption scheme without trustworthy system authority, we point out that in original scheme, the unforgeability characteristic can not be preserved since the insider attackers inside the signcryption group can forge the new legal message with their own information. And we then propose a new scheme which is inspired by the intractability of discrete logarithm in finite field, that is, to insert the sender＇ s private data into the encrypted session. Apart from some security characteristics in the old scheme, our analysis shows that the new scheme also has the advantages of unforgeability, prevention of misuse and non-repudiation, etc.