Research On Security And Anonymity Protection Mechanisms Under DHT Network

With the promotion and popularity of P2 P technology, the security and privacy issues o f P2 P network are also increasingly prominent, and the malicious nodes in P2 P network ha ve brought great impacts on users and normal operation of the whole P2 P network. In rece nt years, research based on P2 P anonymous communication protocol attracted much attention.The strength of anonymous of communication systems is an important indicator to judge a nonymous technologies, and it also has important significance to improve and perfect anony mity systems.This thesis describes the basic principles and characteristics of DHT network as well as the basic concepts of anonymous communication technologies; gives a qualitative and quantitative analysis of the degree of anonymity; describes the main anonymous mechanism and the typical anonymous communication systems, pointing out research status, trends and problems of anonymous communication system.Secondly, for Kad network, which is the typical application of DHT network, the vulnerabilities and security issues in Kad network have been analyzed and researched. Given three Kad network-based attacks: asymmetric bandwidth attacks, routing pollution attacks and index pollution attacks. They are validated through the design and implementation of prototype systems, and with the corresponding defense strategies.Finally, for the DHT network privacy protection issues, this thesis proposes a new anonymous communication protocol based on DHT network, A-DHT, in order to obtain a strong anonymity, reduce costs in anonymous communication and improve efficiency. Resource release, resource search and resource transmission are considered in the design of anonymous mechanism in A-DHT. It introduces session key mechanism and random forwarding mechanism of forwarding probability decreasing geometric to achieve strong anonymity of the entire system and transmission efficiency. By calculation and theoretical analysis to anonymity, it shows that A-DHT protocol has a better anonymity at the same time it ensures the transmission performance and network efficiency.