中文摘要：

网络编码在提高网络吞吐量方面有很大的优势,但是它极易受到污染攻击.目前针对此问题的多数解决方案都是针对有中心机制的网络.针对无中心机制的移动自组织网络,考虑移动自组网中节点的移动性和无固定的可信任第三方中心机制,结合已有的声誉机制研究,提出一种基于声誉机制的抗污染攻击方案对抗网络编码中的污染攻击.该方案采用对污染攻击进行检测和定位,在检测污染攻击存在的情况下,通过声誉机制对恶意节点进行定位,从而达到抗污染攻击的目的.通过实验仿真,与已有的方案进行比较,实验结果表明：针对无中心机制的方案在包的接收成功率上有一定提高,并且在多个恶意节点存在的情况下依然可以准确定位出恶意节点并将其隔离.

英文摘要：

Network coding is to apply innovative error-correction coding techniques in the network layer to improve network performance in both wired and wireless networks.It has been theoretically shown and experimentally demonstrated that if it is properly applied,it can significantly improve endto-end network throughput,and hence has attracted tremendous attention in the last fifteen years.Unfortunately,this technique also has some serious drawbacks.One of the major problems is its vulnerability to pollution attacks,where malicious nodes can inject corrupted packets to mess up with the decoding process.To deal with this serious problem,many schemes have been proposed in the literature,but most of them are centralized in the sense that a trusted central authority may be required.In this paper,we propose a novel distributed defense scheme based on some reputation mechanism by taking advantage of node mobility.The fundamental idea is to apply an effective reputation mechanism to locate potential malicious nodes whenever suspected polluted packets are detected.We have conducted extensive comparison studies of our proposed scheme and the existing ones,and demonstrated that the proposed scheme can achieve high successful packet delivery ratio by effectively locating and isolating the malicious nodes,even when there exist multiple malicious nodes in the network.