密钥管理和代理签名的相关研究

【作者】 张忠；

【导师】 徐秋亮；

【作者基本信息】 山东大学 ， 计算机应用技术， 2005， 硕士

【摘要】 本文的主要内容分为两部分,第一部分讨论多播安全的一个核心问题——组密钥管理;第二部分讨论代理签名,尤其是门限代理签名体制的设计以及安全性分析。 多播是Internet上许多应用的基础,因此成为当前研究的一个热点问题。安全是多播研究中急需解决的问题,其中最为核心的问题就是多播组的密钥管理。目前已有的组密钥管理协议主要包括组密钥分配协议和组密钥协商协议,总体来说,他们各有优缺点,适用于不同的情况。本文首先介绍了组密钥管理的概念以及分类,并在组密钥分配方案的三类中各选一个经典的协议做了详细的论述和分析,主要包括GKMP、LKH和Iolus方案,随后又讨论了两种经典实用的组密钥协商方案——GDH和TGDH。在充分分析现有方案的前提下,文章提出虚拟动态子群的概念,并构建了基于LKH的分配式虚拟动态子群组密钥管理方案和基于GDH的协商式虚拟动态子群组密钥管理方案,用以解决一些复杂群组结构的组密钥管理需求,如网格的虚拟群组(VOs),微软解决方案MSF(Microsoft Solution Framework)组织结构等。 本文的另一个主要内容是代理签名,它作为一种新型的数字签名方案,首先是由Mambo et al.在1996年提出,在一个典型的代理签名方案中,原始签名者授权代理签名者代表其产生有效的代理签名,验证者在验证代理签名有效性的同时验证授权。 近年来,许多学者又将门限机制和代理签名相融合,提出各种门限代理签名方案。在一个(t,n)门限代理签名方案中,当且仅当至少有t个代理签名人联合,可生成一个有效的代理签名。本文按照代理签名研究的发展顺序,回顾并分析了经典的代理签名及门限代理签名方案。匿名的门限代理签名方案在抵抗合谋攻击方面一直没有很好的办法,1999年Sun Hung-Min提出了具有已知签名人的门限代理签名方案,试图通过可追踪的机制解决合谋攻击问题。2000年Hwang,Lin和Lu等人指出Sun的方案依然会受到合谋攻击的威胁,并提出一个改进方案,但于2004年Tzeng等人指出他们的方案会遭受原始签名人伪造攻击,并提出一个新的改进方案,很可惜该方案不能正常执行。本文对Hwang等人的方案做了另一个新的改进,然后分析指出新方案既能有效的抵抗合谋攻击,也不会受到原始签名人伪造攻击的威胁。合谋问题的另一解决思路是通过引入SA,首次提出是在Hsu等人的方案中。但于2004年Yang等人指出Hsu等人的方案效率不高,并提出改进方案。本文对Yang等人的方案进行了分析,指出他们的方案会遭受原始签名人伪造攻击,并进一步给出两种改进方案。文章最后给出一种新型的门限代理签名方案,具有众多优良的性质。更多还原

【Abstract】 The content of this thesis consists of two parts. The first part discusses the key element of multicast security—Group Key Management, and the second part talks about Proxy Signature, especially about the design and cryptanalysis to Threshold Proxy Signature Scheme.As the basis of many current Internet applications, multicast has become a hottest research topic now. Security is an important issue of multicast, and group key management is the key one of most safety demands. At present, group key management mainly divided into goup key distribution and group key agreement, both of them have their own character and can be used in different applications. Firstly, the concept and category of group key management will be presentated in this thesis. Secondly we discuss five classic group key management schemes: GKMP, LKH, Iolus, GDH and TGDH. Finally based on existing protocols, we propose the concept of virtual dynamic security subgroup, then design distributed virtual dynamic subgroup scheme (DVDSG) and agreed virtual dynamic subgroup scheme (AVDSG), which can efficient meet the requirement of security to complex group structures, such as Microsoft Solution Framework (MSF) and Virtual-Organizations (VOs) which are based on grid.Another content of this thesis is proxy signature, The concept of the proxy signature scheme was first introduced by Mambo et al. in 1996, which allows the original signer delegates her/his signing capability to a designated person, called a proxy signer. The proxy signer could stand proxy for the original signer to generate signatures, referred to as proxy signatures.Following the development of the proxy signature scheme, the threshold proxy signature scheme was also widely studied recently. A (t, n) threshold proxy signature scheme allows at least t proxy signers of a proxy group to sign messages on behalf of the original signer. Since there is no efficient means for anonymous threshold proxy signature to withstand the conspiracy attack during long time, Sun Hung-Min proposed an efficient nonrepudiable threshold proxy signature scheme with known signers in 1999, which tryed to solve it through track. In 2000, Hwang et al. pointed out the Sun’s scheme still suffered from the threat of the conspiracy attack then proposed a secure nonrepudiable threshold proxy signature scheme (called as HLL scheme hereafter) to improve Sun’s scheme. In 2004 Tzeng et al. showed a forge attack against HLL scheme and proposed an improvement scheme to remedy HLL scheme. Unfortunately, Tzeng et al.’s scheme did not work, so we propose a new improvement of HLL scheme. Anothermethod to solve the conspiracy attack was importing SA, which worked out by Hsu et al. in 2001, and in 2004 Yang et al. proposed an improvement scheme with high efficiency. In this thesis we point out a cryptanalysis of their scheme. Furthermore, we improve the security of the threshold proxy signature scheme which remedies the weakness of Yang et al.’s scheme. In the end we propose a more efficient scheme without SA, which is secure against the conspiracy attack and original signer’s forgery attack.更多还原