Towards Efficient Traffic-analysis Resistant Anonymity Networks

Existing IP anonymity systems tend to sacrifice one of low latency, high bandwidth, or resistance to traffic-analysis. High-latency mix-nets like Mixminion batch messages to re-sist traffic-analysis at the expense of low latency. Onion routing schemes like Tor deliver low latency and high band-width, but are not designed to withstand traffic analysis. Designs based on DC-nets or broadcast channels resist traf-fic analysis and provide low latency, but are limited to low bandwidth communication. In this paper, we present the design, implementation, and evaluation of Aqua, a high-bandwidth anonymity system that resists traffic analysis. We focus on providing strong anonymity for BitTorrent, and evaluate the performance of Aqua using traces from hundreds of thousands of actual Bit-Torrent users. We show that Aqua achieves latency low enough for efficient bulk TCP flows, bandwidth sufficient to carry BitTorrent traffic with reasonable efficiency, and resis-tance to traffic analysis within anonymity sets of hundreds of clients. We conclude that Aqua represents an interesting new point in the space of anonymity network designs