【摘要】 简述了代理签名及其应用的发展状况,对Lee等提出的两种新的改进的代理签名方案的安全性进行了分析,并且提出了一些针对这两个方案的攻击方法,分析了其受攻击的根本原因。针对两个方案的这些缺陷,我们提出了两个新的改进方案,而且对新的方案的安全性和复杂性进行了分析,通过分析得到在不增加复杂性的前提下,安全性得到加强,能够抵挡本文中列出的所有攻击。并且其安全性等于解离散对数,因此新的改进方案是安全的。更多还原

【Abstract】 The paper briefly describes the characteristics and development of the proxy signatures.And then analyzes the security of the two Lee et al proposed improvement proxy signatures based on the MUO schemes,but we find there are some ways to attack the new schemes.To avoid these attacks,we revise the two schemes,which could resist all the attacks that we list.Finally through analysis the new schemes,we get the conclusions that the new schemes security equal to the difficult of the discrete logarithm problems,and the complexity as the same of the previous ones.更多还原