【作者】 卢三超；

【导师】 王林；

【作者基本信息】 西安理工大学 ， 电路与系统， 2007， 硕士

【摘要】 随着网络技术的飞速发展，用户端系统资源的丰富以及网络带宽的快速增加，传统的Client／Server网络应用模式中服务器的性能瓶颈以及单点失效的问题不仅限制了用户端资源的充分利用，同时越来越无法满足新的分布式应用的需求。而Peer-to-Peer(P2P)网络在协同工作、分布式信息共享、大规模并行计算等方面显示出独特优势，使其成为新的发展热点。虽然目前的P2P网络比传统的C／S有着诸多的优势，但其分布式的网络结构和非集中化管理的网络模式，也给网络带来了许多问题。如对整个网络的管理、监控都非常困难，许多P2P应用程序都对其对等设备只有微弱的控制能力，很容易导致整个网络陷入混乱无序的状态。并且因P2P网络高度的自治性和动态性也导致了许多安全策略方面的问题。显著的表现为应用中大量欺骗行为的存在以及不可靠的服务质量，网络的可用性差。在现实中人们很容易信任eBay这样的大型网站是安全的，而在P2P网络中共享的资源都是由网络的另一端某个素不相识的节点自愿提供的，且节点都是以自由和匿名的方式登陆，系统很难知道加入的节点是否是恶意节点，是否被攻击者控制等，因此建立一个有效的信任系统来管理网络是必要的。关于P2P信任模型的研究始于上世纪90年代后期，但由于已提出的信任模型结构复杂，对用户行为的要求也相对严格，其算法在对等网络里难以实现。基本上都停留在理论研究阶段，并不能推广到对等网络中去应用。本文将建立一种基于幂律的信任模型，这个模型利用了节点过去在网络中的历史经验，建立了两个节点之间的信任关系，更加有效的去解决网络中信任关系，而其算法比较简洁，比一些具有复杂算法的信任模型更适合在现实网络中的应用。该模型能够增强网络可用性，具有结构简单、可靠性强的优点。随后研究了如何在对等网络中建立信任系统，讨论了建立信任系统要考虑哪些问题以及具体的实现过程。更多还原

【Abstract】 With the developing technology of network, enriching resource of consumer node system and increasing bandwidth of network, the problems brought by servers’ function obstacle and nodes’ losing efficiency in traditional Client/Server model not only restrict us to make the best of consumer node’s resource but also cannot meet the need of distributed pattern. And the advantage shown at the collaboration, distributed information communion, large-scale parallel computing in Peer-to-Peer (P2P) network is so particular that it becomes a developmental hot point.Although there is a lot of advantage in P2P network compared with traditional C/S network, its distributed structure and nonconcentrated management also bring some questions to itself. Such as it is difficult to administer or control the whole network, and many application procedures have faint ability to dominate P2P equipments, it is easily to plunge the net into disordered state. At the same time, the problems of some security strategies are resulted in the altitude autonomous rule and dynamic manner of P2P. Especially, there are lots of cheating behaviors, unreliable quality of service and low usability of network. We usually believe that large-scale website, as eBay, is safe in practice, but in the P2P network, things are not like that. The shareable resource is provided by a complete unknown node which land the network freely and anonymously in the P2P, so it is hard to know the node is vicious or not, whether to be controlled, and therefore it is necessarily to make a reputation system to manage the P2P network.The research of reputation model began at last century 90s. The algorithm is hard to realize in the P2P because of complicated model in reputation system and strict demand for free consumers, and the study is rested on theory and cannot be spread. The thesis has set up a reputation model system based on power-law. This model makes fully use of the past experience of node itself and builds reputation relation between two interactional nodes, so it is effectively to solve the problem of lack trust in P2P network. Furthermore, this algorithm is compactly and more useful when apply it in real network, and this model can enhance P2P’s usability and make it more sampler and trustable. Follow then, how to build the reputation system in P2P network is studied, and we also discuss the problem that we meet and explain the process of building the reputation system.更多还原