Rendezvous tunnel for anonymous publishing

Abstract

Many anonymous peer-to-peer (P2P) file sharing systems have been proposed in recent years. One problem that remains open is how to protect the anonymity of all participating users, namely, reader, server and publisher. In this work we propose a novel solution for a P2P file sharing system. Our solution provides overall anonymity to all participating users. Servers in our system store shares of documents, and each share is reached through a rendezvous tunnel between the server and an address given by a hash of the document's name. To publish a document, the publisher first divides the document into shares, for each share finds the address of the entrance to the tunnel by hashing the document's name. Next, the publisher uses anonymous communication to reach the entrance of the rendezvous tunnel. We then use a random walk and an anonymous key exchange scheme to set keys along the rendezvous tunnel. The publisher finishes by inserting the shares into the servers through the rendezvous tunnels. A reader wanting to retrieve the document operates in a similar manner. The reader finds the address of the entrance to the rendezvous tunnels by hashing the document's name. Then, the reader uses anonymous communication to reach the entrance of the tunnels, retrieves the shares anonymously and reconstructs the document.The novelty of this work is threefold. First, we introduce an anonymous key exchange protocol secure against an honest but curious adversary. The anonymity of the protocol is proved on the basis of the Decisional Diffie Hellman (DDH) problem. Second, we propose two solutions to build the rendezvous tunnel: basic and advanced. The basic solution is *