【作者】 冯真；

【导师】 张红旗；

【作者基本信息】 解放军信息工程大学 ， 计算机应用技术， 2006， 硕士

【摘要】 由于P2P网络具有开放性、匿名性等特点，P2P网络中资源的质量很难保证，有些恶意节点利用P2P网络大肆传播病毒、木马等。为此，本文通过信任和声誉系统的方法来解决P2P网络中资源提供节点的可信问题，从而避免节点盲目地下载资源。 论文重点分析了现有的一些P2P环境下的声誉系统，如Xrep、PeerTrust、Pablano等，并设计了一种增强型声誉系统。该声誉系统由信任评估模块和安全传输协议组成。与典型的声誉系统相比，该声誉系统除了评估信任时考虑的因素更全面外，还提出了将信任分为若干个状态，处于不同状态时评估信任的算法会有所区别，这样，所得出的信任值更加精确合理。论文对所设计的声誉系统的安全性进行了分析，并使用Java编程模拟了该系统。从模拟的结果可以看出，使用本文声誉系统时节点的交互成功率不仅较未使用声誉系统时大大提高，而且比Pablano声誉系统也有所改进，尤其是在恶意节点比较多的情况下。 最后，在声誉系统应用中，本文引入了自动信任协商，即将基于信任计算的方法与基于证书的方法结合起来，并就如何结合做了一些探讨。可以看出，自动信任协商的引入降低了单纯依靠声誉系统时存在的风险，保证了敏感信息传输的高可靠。更多还原

【Abstract】 The resources in P2P networks are not dependable because of the open and anonymity nature of P2P networks, some malicious peers may propagate viruses and Trojan horses via P2P networks. In this paper, the approach of trust and reputation systems is used to solve the trustworthiness problems of resource providers in P2P networks, so as to avoid downloading resources blindly.In this paper, some reputation systems in P2P environment at present are analyzed, such as Xrep、 PeerTrust、 Pablano, etc, and an enhanced reputation system is designed. The designed reputation system consists of a trust evaluation module and a secure transport protocol. Contrast to most reputation systems, not only more comprehensive factors are considered on evaluating trust, but also divides trust into a few states, the algorithm of evaluating trust is different at different trust state. So, the trust value is more precise and reasonable. In this paper, we analyze the security of the designed reputation system, and simulate the system by java programs. From the result of simulation, it can be proved that the success rate of peers’ interactions with our reputation system is not only greatly improved contrast to without, but also better than Pablano reputation system, especially when there are a lot of malicious peers.Finally, automated trust negotiation is introduced to the application of reputation system, in other words, the method based on trust evaluation and the method based on credentials are integrated, then the approaches of integration are discussed. It is concluded that the introduction of automated trust negotiation has reduced the risk of depending on reputation systems only, so the dependability of sensitive information transportation is guaranteed.更多还原