[tor-dev] Researching Tor: Quantifying anonymity against a global passive adversary

George Danezis georged at gmail.com
Wed Jun 3 17:58:14 UTC 2015

Hello Florian,

I just saw your mail on tor-dev. The assumption a number of us have
been using in our work, is that if the adversary observes a circuit at
two different locations, then it can link it. This is a bit like
assigning a unique ID to each circuit, and assuming that seeing the
link / node on which the circuit operates, reveals this ID. Then you
can use techniques such a monte-carlo simulation to evaluate the
probability say Alice is talking to Bob as described in this paper:
The Bayesian Traffic Analysis of Mix networks.
Carmela Troncoso and George Danezis. ACM CCS 2009.

Also: what are your plans for the future? I am advertising a PhD on
this topic if that is something that would interest you:



On Wed, Jun 3, 2015 at 12:38 PM, Florian Rüchel
<florian.ruechel.tor at inexplicity.de> wrote:
> Hi there,
> I am currently writing my Master's thesis about Mix networks & Tor (was
> on list previously). I am currently at a point, where I'd like to
> practially quantify anonymity. That is, given a pcap, I want to anaylze
> how successful an adversary can determine whether a specific client
> talked to a specific service. Since I run all of this in a simulation
> (using Shadow), I have access to ground truth and can determine the
> traffic, network size, etc. arbitrarily.
> The idea behind all of this is to integrate a Mix relay on each Tor node
> and to watch how the adversarys success behaves. However, I have a hard
> time finding material on such attacks, i.e. papers that closely examine
> this scenario (and perhaps have conducted some simulation and/or
> measurements themselves, beyond simple theory). The thing is that this
> is only part of the research and I'd really prefer if I could build this
> upon work of others instead of starting from scratch.
> Do any of you know of such papers or corresponding research?
> Regards,
> Florian
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