A Tune-up for Tor: Improving Security and Performance in the Tor Network

The Tor anonymous communication network uses selfreported bandwidth values to select routers for building tunnels. Since tunnels are allocated in proportion to this bandwidth, this allows a malicious router operator to attract tunnels for compromise. Since the metric used is insensitive to relative load, it does not adequately respond to changing conditions and hence produces unreliable performance, driving many users away. We propose an opportunistic bandwidth measurement algorithm to replace selfreported values and address both of these problems. We also propose a mechanisms to let users tune Tor performance to achieve higher performance or higher anonymity. Our mechanism effectively blends the traffic from users of different preferences, making partitioning attacks difficult. We implemented the opportunistic measurement and tunable performance extensions and examined their performance both analytically and in the real Tor network. Our results show that users can get dramatic incr...

• Type: Conference
• Year: 2008
• Where: NDSS
• Authors: Robin Snader, Nikita Borisov
• Keywords: Computer Networks, NDSS 2008, Opportunistic Bandwidth Measurement, Tor Anonymous Communication, Users Tune Tor