Cashmere: Resilient Anonymous Routing

Li Zhuang
Feng Zhou
Ben Y. Zhao
Antony Rowstron

ACM/USENIX 2nd Symposium on Networked Systems Design and Implementation (NSDI 2005)

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Paper Abstract

Anonymous routing protects user communication from identification by third-party observers. Existing anonymous routing layers utilize Chaum-Mixes for anonymity by relaying traffic through relay nodes called mixes. The source defines a static forwarding path through which traffic is relayed to the destination. The resulting path is fragile and shortlived: failure of one mix in the path breaks the forwarding path and results in data loss and jitter before a new path is constructed. In this paper, we propose Cashmere, a resilient anonymous routing layer built on a structured peer-to-peer overlay. Instead of single-node mixes, Cashmere selects regions in the overlay namespace as mixes. Any node in a region can act as the MIX, drastically reducing the probability of a mix failure. We analyze Cashmere's anonymity and measure its performance through simulation and measurements, and show that it maintains high anonymity while providing orders of magnitude improvement in resilience to network dynamics and node failures.