Rendezvous tunnel for anonymous publishing: Clean slate and tor based designs

Abstract

Anonymous communication, and in particular anonymous Peer-to-Peer (P2P) file sharing systems, have received considerable attention in recent years. In a P2P file sharing system, there are three types of participants: publishers that insert content into the system, servers that store content, and readers that retrieve content from the servers. Existing anonymous P2P file sharing systems confer partial anonymity. They provide anonymity to participant pairs, such as servers and readers or publishers and readers, but they do not consider the anonymity of all three types of participants. In this work we propose two solutions for anonymous P2P file sharing systems. Both of our solutions provide anonymity to all three types of participants. The proposed solutions are based on indexing by global hash functions (rather than an index server), dispersal of information, and three anonymity tunnels. Each anonymity tunnel is designed to protect the anonymity of a different user (publisher, server, or reader). In both solutions the reader and publisher tunnels are sender anonymity tunnels. In the first solution the third tunnel is a rendezvous tunnel, constructed by means of a random walk and terminating at the server. In the second solution, which is based on Tor, the third tunnel is built using Tor's hidden services. The first solution preserves anonymity in the presence of a semi-honest adversary that controls a limited number of nodes in the system. The second solution is based on Tor primitives, coping with the same adversary as that assumed in Tor. The second solution enhances Tor, ensuring publisher, server, and reader anonymity. © 2011 Springer-Verlag.