面向半分布式P2P系统的可靠节点交换机制

P2P系统中广泛使用的来源交换(PEX)技术为系统用户提供了丰富的节点资源，加快了节点交换速度，同时也带来了不可避免的安全隐患，恶意节点可以通过来源交换对正常节点的邻居列表进行污染。首先分析了现有来源交换技术存在的安全隐患，讨论了导致这些安全隐患的核心因素；其次，以来源交换的安全性分析为基础，提出了一种面向半分布式P2P系统的安全节点交换机制。该机制借鉴基于信任评估的激励技术，通过给出超级节点的信任评估方案，引入节点来源信任的概念，以节点的来源交换信任值为支撑，控制节点间的来源交换。最后，对提出机制进行了实验性能分析。实验结果表明，由于网络异构性所存在的信任值错误计算问题，所提出的交换机制虽然会导致约2.5%比例正常的节点交换失效，但可大幅度降低正常节点参与恶意节点传播和污染的情况，从而在总体上提升了P2P系统的可靠性。

Reliable peer exchange mechanism based on semi-distributed peer-to-peer system

Peer Exchange (PEX) technique used vastly among Peer-to-Peer (P2P) systems brings more peers along with security leak. Malicious peer can pollute normal peer's neighbor table by exploiting peer exchange. First, this paper analyzed the leak and discussed the main reasons. Second, based on the analysis, a peer exchange mechanism based on semi-distributed peer-to-peer system was proposed. It introduced an approach to estimate the super node's trust value based on incentive mechanism. A concept of peer's source trust value, which is the foundation of the mechanism proposed in this paper, was proposed also. By using peer's source trust value, the goal of controlling peer exchange was finally achieved. The experimental results show that, due to the trust value miscalculation caused by the heterogeneity of the network, 2.5% good peers are denied being exchanged, pollution of good peers' neighbor table and passive infection from good peers are significantly reduced due to the mechanism proposed in this paper. System reliability is guaranteed then.