TitleStrong, Scalable Anonymity in Dissent
Publication TypeConference Paper
Year of Publication2012
AuthorsWolinsky, D. Isaac, H. Corrigan-Gibbs, B. Ford, and A. Johnson
Conference NameTenth USENIX Symposium on Operating Systems Design and Implementation (OSDI '12)

Current anonymous communication systems exhibit a trade-off between weak anonymity among many nodes, via onion routing, or strong anonymity among a few nodes, via DC-nets. To addresses this trade-off we introduce Dissent, a practical anonymity system that increases by 1-2 orders of magnitude the anonymity set sizes achievable using traffic-analysis-resistant techniques. Dissent's design achieves these gains via a client/server architecture, in which many unreliable clients partially offload communication and computation costs to a smaller and more robust, but decentralized, set of servers. Clients trust only that at least one server in the set is honest, but need not know or choose which server to trust. Unlike the quadratic costs of prior peer-to-peer DC-nets schemes, Dissent's client/server design reduces communication and processing costs to linear in the number of clients, and hence in anonymity set size. Further, Dissent's servers can unilaterally ensure progress, even if clients respond slowly or disconnect at arbitrary times, ensuring robustness against client churn, tail latencies, and DoS attacks. On PlanetLab, Dissent scales to 2,000 online participants and offers latencies as low as 3 seconds for network sizes of 500. An anonymous Web browsing application also shows that Dissent's performance suffices for interactive communication within smaller local-area groups.

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