ZG离线TTP公平非否认协议的安全性分析及改进

Analysis and improvement of ZG off-line TTP non-repudiation protocol

对ZG离线TTP(trusted third party)公平非否认协议及其一种改进方案进行了分析,针对原协议因引入协议有效期而存在消息延迟攻击的问题以及改进方案存在子协议被滥用的问题,提出2种新的改进方案。2种方案侧重点不同,分别适用于不同的场景,能够保证非否认性和公平性的同时,避免消息延迟攻击和子协议被滥用。第一种方案适合于对协议效率要求比较高,而且协议被滥用不会影响参与协议主体的利益的情况;第二种方案可用于需要防止子协议被滥用的情况。

Based on the weakness of ZG off-line TTP(trusted third party) non-repudiation protocol because of using pro-tocol deadline, the improvement of the ZG off-line TTP non-repudiation protocol was given, which eliminated the delay-ing resolve request attack and ensured non-repudiation and fairness.Therefore, two kinds of improvement of ZG off-line TTP non-repudiation protocol were given, which had different point of focus.Among them, the first one could eliminate delaying message attack in ZG protocol;the second one also had the property of preventing the abuse of sub-protocol be-sides eliminating delaying message attack.The first one is suitable for electronic payment and certified email, but the second one is suitable for digital contract signature.