【作者】 傅建庆；

【导师】 平玲娣；

【作者基本信息】 浙江大学 ， 计算机科学与技术， 2010， 博士

【摘要】 近几年来,随着技术的不断发展和网络的日趋演进,各种无线技术在相互角逐的同时,也正在逐步走向互补融合。未来无线网络的发展趋势必然是在保留现有各种无线技术的基础上,通过一种统一的移动管理机制进行整合,从而为用户提供无时无刻、无所不在的网络接入服务。3G移动通信网络作为移动通信技术的代表,能在广域范围内提供较好的漫游服务,但是它提供的数据传输速率以及网络带宽较小,费用较高。WLAN作为另一种常见的无线接入网络,能提供相对较高的速率,适合于多媒体信息的传输,并且价格较低,但是它的网络覆盖范围较小。3G和WLAN的互联能充分发挥两者的互补特性,为用户提供更好的网络接入服务。实现3G和WLAN的互联是一个非常复杂的系统工程,需要考虑许多关键性问题,其中安全是需要重点考虑的问题之一。3G-WLAN互联网络需要一种与底层技术无关的接入认证和计费机制,在用户初次接入网络时,需要对用户进行合法性验证,在用户接受服务过程中,需要对用户安全地进行计费。本文主要基于对匿名认证和非否认性计费的研究,提出了对现有3GPP规范中的接入认证和计费协议的改进,取得了以下研究成果：(1)提出了一个针对3G-WLAN互联网络的WLAN匿名接入认证协议。协议基于代理签名和椭圆曲线加密技术,通过让部分用户设备随机地共享由归属网络分配的代理签名密钥对,实现了用户设备和3GPP AAA Server的相互认证,用户设备和3GPP AAA Server之间的主密钥协商,以及UE和WLAN接入网之间的会话主密钥安全分发,同时解决了原协议中存在的用户身份泄露、拒绝服务攻击和虚假接入点攻击等安全问题。(2)提出了一个针对3G-WLAN互联网络的WLAN接入快速重认证协议。协议采用双哈希链机制不但实现了用户设备和3GPP AAA Server之间的双向认证以及用户设备和WLAN接入网之间的会话密钥安全分发,还解决了原协议中WLAN接入网无法过滤非法认证请求、不能抵抗对归属网络的拒绝服务攻击的问题。接着针对重认证最大次数受限于哈希链链长的问题,提出了一种朴素可再生哈希链技术。与基于一次性签名的可再生哈希链技术相比,朴素可再生哈希链技术能有效降低哈希链再生引起的额外计算和通信负载。(3)提出了一种快速3GPP接入认证协议。协议在3GPP接入认证过程中充分利用了之前WLAN接入认证的结果,减少了用户设备和3GPP AAA Server之间的消息交互,降低了通信负载和能量消耗。同时由于省略了EAP-AKA过程,没有消耗认证矢量,因此也减轻了HSS/HLR的工作负担。(4)提出了一种基于哈希链的非否认性在线计费协议。解决了原在线计费协议中存在的用户设备和WLAN接入网之间计费纠纷的问题。针对长哈希链的高计算、存储负载,提出了基于二叉树的高效哈希链遍历算法,并实现了在任意链长下的遍历复杂度分析。分析结果表明,对长为n的哈希链进行遍历时,只需要[log2 n]+1大小的辅助空间,并且全部遍历所需的计算次数不大于n[log2 n]/2。此外算法还提供了时空复杂度转化机制,从而能在需要时进一步降低计算负载或存储空间。更多还原

【Abstract】 In recent years, as the growing of the technology and the evolution of the network, various wireless networks are gradually moving towards integration of complementary when at the same time compete with each other. It is the trend of the future wireless networks that providing a unified mobility management system to integrate these wireless network in order to provide ubiquitous network access services to the mobile users all the time. As the representative of mobile communication systems, the 3G mobile communication network can provide a good range of wide-area roaming, but it provides low data transfer rates and network bandwidth, and is expensive. As the most common wireless access technology, WLAN can provide a higher rate, is suitable to transmit large amounts of multimedia information, and is inexpensive, but the network coverage is small. The integration of 3G and WLAN can take full advantage of them, and provide users with better services.It is a very complicated system engineering to integrate 3G and WLAN network, needs to consider many key issues, one of which is security. In the network integrating 3G and WLAN, it is necessary to provide common authentication and billing mechanisms independent of the underlying wireless technology.In this dissertation, we studied anonymous authentication and undenial charging protocols in 3G-WLAN integrated networks, and several improvements to the standard proposed by 3GPP were put forward as follow.(1) An anonymous authentication protocol for WLAN Direct IP Access was proposed, which is based on proxy signature and the elliptic curve encryption, allows a pair of proxy signature keys to be shared among some mobile devices randomly, not only archives mutual authentication and master key agreement between user equipment and 3GPP AAA Server, distribution of the session master key between user and WLAN, but also addressing the security holes in the original protocol such as identity leak, DoS attacks and false AP attacks.(2) A new fast re-authentication protocol for WLAN Direct IP Access was proposed based on dual hash chains mechanism, which not only realizes the mutual authentication between user equipment and 3GPP AAA Server, the secure distribution of the session master key between user and WLAN, and anti-replay attack, but also achieves anti-DoS attack which can’t be provided by the original protocol. To resolve the issue that the maximum times of re-authentication is limited to the length of hash chain, we proposed a simple algorithm for hash chain regeneration, compared to one-time-signature-based algorithm, the proposed algorithm greatly reduces the computational load and communication load.(3) An efficient WLAN 3GPP IP access authentication protocol was proposed, which makes full use of the result of WLAN direct IP access authentication to avoid the duplicated mutual authentication between UE and the 3GPP AAA Server, reduces the computational load and communication load. At the same time, as EAP-AKA procedure is omitted, the proposed protocol does not require authentication vectors from HSS/HLR, which reduces the workload of HSS/HLR.(4) A non-repudiation offline charging protocol was proposed based on hash chain, which settles the matter that the original off-line charging protocol can’t resolve the billing dispute which would happen between the UE and WLAN or between the UE and the visited network. As the computing load or storage load will be high when the length of hash chain is long, we proposed an efficient hash chain traversal algorithm based on binary tree, and realized the complexity analysis. The analysis results show that, when the length of the hash chain is n, the auxiliary space that the proposed algorithm needs is |log2 n|+1, and the number of hash calculations that the proposed algorithm needs during traverse is not larger than n|log2 n|/2. Further more, the algorithm can reduce time complexity by increasing space complexity, visa verse.更多还原