Study Of Structured P2P Anonymous Communication System

Recently, the security demands for network application have become higher and higher. Cryptography can provide confidentiality of information, but is unable to stop the attackers to obtain sensitive information by analyzing network traffic. Anonymous communication, being able to protect the identities of the communication participants or hide their communication relationships, has satisfied the security needs of people and achieved more and more attentions. The development of P2P technology has spurred people to introduce anonymous communication technology into P2P network. However, the study of anonymous communication based on P2P has aimed at anonymity and system scalability at present. People have considered little on revocable anonymity abusing and penalty mechanism on selfish behavior and this has influenced system anonymity and efficiency.Based on detailed study and analysis of PGACS system, the P2P grouping anonymous communication system, in order to improve the controllability of selfish behavior and anonymous abusing behavior in anonymous system, this paper proposes CACS (controllable anonymous communication system based on structured P2P) with two layers architecture design and implementation, where peers are partitioned into groups to organize the network. According to peer's hashing mapping of IP address, the peers with same suffix are grouped into same group. On these grounds, the system consists of several groups and each user can join one group. The system assigns initial credit to new peer, and dynamically adjusts the credit according to two quotas, the length of peer's online time and offered service for other peers. CACS has achieved revocable anonymity by exploiting cryptography and penalty mechanism against selfish behaviors.The CACS system was implemented on JXTA architecture. By introducing the main architecture, the composition of the system and the design of each module, implementation procedures of each module and the key functions have been explained in detail. The validity of the basic modules has been tested in real environment. PeerSim, the simulate tool of P2P network, has been used further to simulate the system in a large-scale. Both theoretical analysis and simulation results show that the system could provide the same anonymity as PGACS, and the number of selfish nodes and malicious nodes has little effect on the performance of the system.Finally, the paper concludes and discusses the future work of research.