CS Research Talk: Client-Location-Aware Path Selection in Tor

Aaron Johnson
U.S. Naval Research Laboratory
Computer Scientist

Wednesday, September 29, 2021
11:30a.m. – 12:30 p.m.
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In Person @
800 22nd Street NW, Washington, DC, 20052
SEH Room 2000

Abstract

Much research has investigated improving the security and performance of Tor by having Tor clients choose paths through the network in a way that depends on the client's location. However, as we describe in this talk, this approach can lead to serious deanonymization attacks and performance degradation. As a solution to these problems, we present the CLAPS system for performing client-location-aware path selection. CLAPS puts a strict bound on the leakage of information about the client's location, where the other systems could completely reveal it after just a few connections. It also guarantees a limit on the advantage that an adversary can obtain by strategic relay placement, which we demonstrate to be overwhelming against the other systems. Finally, due to a powerful formalization of path selection as an optimization problem, CLAPS is approaching or even exceeding the original goals of algorithms to which it is applied, while solving their known deficiencies.

Bio

Dr. Aaron Johnson is a computer scientist at the U.S. Naval Research Laboratory. His research interests include private communication and privacy-preserving data analysis. He has performed foundational mathematical research in the area of anonymous communication by modeling and analyzing the security of onion routing. He has also applied mathematically-rigorous privacy-preserving methods to publishing sensitive genetic and network data. Much of his work has been focused on the Tor network, which is an onion-routing network used by millions of users daily to secure their communications. He designed several improvements to Tor, including denial-of-service defenses, faster onion services, privacy-preserving network monitoring, and improvements to Tor's path selection. Many of these results have been incorporated into the Tor network and provide enhanced security, performance, and utility to its many users. Dr. Johnson received his Ph.D. in 2009 from the computer science department at Yale University and completed postdoctoral training at the University of Texas at Austin.