[tor-project] May 2018 report for the metrics team

Kate Krauss ailanthus at riseup.net
Mon Jun 25 17:29:33 UTC 2018

Hello metrics folks:

I wanted to note that this talk took place today in DC on Tor metrics;
here is the abstract:

Just an FYI--hope everyone is enjoying their summer.



3:40 p.m. - 4:05 p.m.
Speaker: Ryan Wails (U.S. Naval Research Laboratory)
Title: Tunable Transparency: Secure Computation in the Tor Network
Abstract: Tor is a widely popular tool for online privacy. Despite its
focus on privacy, Tor benefits from some transparency about the
operation of its network. Measurements of Tor help direct its
developers, inform its users, and guide policymakers. Existing
approaches to making these measurements, including Tor's current
techniques, are limited in the types of measurements that can be made.
    We present a system that uses secure multiparty computation (MPC)
protocols to give Tor full power to tune its transparency, that is, to
compute any function of its relays' observations while keeping the
observations themselves private. Our system scales to Tor's thousands of
relays, provides security depending only on Tor's core trust assumption
that a large fraction of its bandwidth is honest, and efficiently makes
use of Tor's network and computational resources. We demonstrate how to
use our system to compute two broadly-applicable statistics: the median
of relay inputs and the cardinality of set-union across relays. We
implement our protocols and experimentally test their performance in
networks like Tor using the Shadow simulator. Our experiments show that,
for a network of Tor's current size, a median can be computed in 25
minutes, given 11 hours of preprocessing, and that set-union cardinality
can be computed in 13 seconds, given 7 hours of preprocessing.


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