Scalable Anonymous Communication System

With the rapid growth and public acceptence of the Internet as a means of communication and information dissemination, concerns about privacy and security on the Internet have grown. Anonymous Communication, since it can protect the identities of the communication participants and hide their communication relationships, has become an essential requirement for many on-line Internet applications and one of the hot spots of research for the network security researchers. However, the research has mainly focued on the anonymous effectiveness, many anonymous communication systems pay little attention to the extra cost of system management and thus affect the scalability of the system.In order to improve the scalability of the anonymous communication system Crowds, this paper has put forward the design and implementation of an anonymous communication system: the SCACS system. The system stems from the divide-and-conquer approach that partitions the network into anonyizing cliques. Each user of the system can join in several of the cliques and initiates the establishment of a random path by selecting users from these cliques. The paper has brought forward two hashing and partition management mechanisms based on two different logical topologies and made qualitative comparisons between them. The two mechanisms are the partition management mechanism based on 2-dimensional coordinate space and the mechanism based on consistent hashing. For the SCACS system based on 2-dimensional coordinate space, the basic functions and implementation procedures of each module have been explained in detail and the system has been evaluated by simulation. The paper also makes quantitative analysis of anonymous effectiveness and the extra cost of system management. The results derived from both probability analysis and simulation test indicate that the new systems can keep almost the same anonymity degree as the original system while efficiently increasing the scalability of the system by decreasing the cost of management. When there are many cliques in the system, the mechanism based on cosistent hashing can help to determine in which cliques each user joins in a more effective mode and improve the efficiency of user location.Finally, the paper sums up the work during the design and development, and discusses the future work of research.