Adapting P2P Mixnets to Provide Anonymity for Uplink-Intensive Applications

Anonymity in Web and Internet communication is a widely investigated problem. Mixnets represent certainly the most concrete and effective approach to achieving the above goal. In general, the drawback of these approaches is that anonymity has a price in terms of traffic overhead and latency, when the global adversary model is adopted. On the Internet, to achieve scalability and not to require relevant infrastructure and networkprotocol changes, only P2P overlay protocols can be used. In recent years, we are seeing a change in Internet traffic. Due to IoT, cloud storage, WSN, M2M, etc., uplink traffic is increasingly growing. An interesting problem to address is whether this new traffic configuration may enable new strategies for improving the effectiveness of P2P mixnet-like approaches. In this paper, we investigate this problem, by considering the most representative Internet-scale P2P mixnet, called Tarzan, which is designed to obtain strong anonymity while preserving low-latency applications. We experimentally demonstrate that changing the cover traffic from bidirectional to unidirectional by making tunnels cyclic is advantageous in the case of uplink-intensive applications. The outcomes of the paper can thus give a contribution to improve mixnet-based approaches in the future Internet.