From DC-Nets to pMIXes: Multiple Variants for Anonymous Communications

Current systems providing anonymous communication with low latency are based on relay-networks. Since a single relay can betray its users, it is necessary to use several relays for each communication which distributes the trust among them. This increases the complexity of the protocols as well as the latency, and lowers the throughput to the one of the worst link used. On the other side, such distributed systems are more difficult to attack and can manage large sets of users. In this paper, we proposed a non-distributed approach by presenting the first relay for anonymous communication that cannot betray its users, the pMIX. The scalability for this relay is reduced as the computational cost grows in O(n²) (n being the number of users connected to it) and therefore pMIXes can only be used to form small anonymity sets. In this paper we present different variants for the pMIX that lower the computational cost either to O(ntimesm) or to O(m²) (m being the number of simultaneous communications). This allows a pMIX to deal with larger groups of users having a small amount of simultaneous communications