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13th USENIX Security Symposium — Abstract

Pp. 303–320 of the Proceedings

Tor: The Second-Generation Onion Router

Roger Dingledine and Nick Mathewson, The Free Haven Project; Paul Syverson, Naval Research Lab


We present Tor, a circuit-based low-latency anonymous communication service. This second-generation Onion Routing system addresses limitations in the original design by adding perfect forward secrecy, congestion control, directory servers, integrity checking, configurable exit policies, and a practical design for location-hidden services via rendezvous points. Tor works on the real-world Internet, requires no special privileges or kernel modifications, requires little synchronization or coordination between nodes, and provides a reasonable tradeoff between anonymity, usability, and efficiency. We briefly describe our experiences with an international network of more than 30 nodes. We close with a list of open problems in anonymous communication.
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