[tor-dev] Website Fingerprinting Defense via Traffic Splitting

[l.m]

Daniel Forster wrote:
> Hello Guys,
>
> it would be great if I could get a few opinions regarding my
> upcoming master thesis topic.
>
> My supervisor is Andriy Panchenko (you may know some of his work
> from Mike Perry's critique on website fingerprinting attacks).
> As a defense, we'd like to experiment with traffic splitting (like
> conflux- split traffic over multiple entry guards, but already
> merging at the middle relay) and padding.
>
> I know that the no. of entry guards got decreased from three to one.
> May it be worth the research or is the approach heading in a not so
> great direction w.r.t. the Tor Project's "only one entry node"
> decision? Or, actually, what do you think in general..?
I think it will be interesting to see how a client of Tor can be
fingerprinted by the guards chosen. In particular if the circuit
length tends to be three and you perform a merge at the middle node.
By watching the incoming n-tuple of guards, having chosen in advance
the role of middle-hop, can clients be identified through correlation
with exit traffic. I'm aware that the choice of guards can already
make a client fingerprintable--but how much more so in this case. This
might not be the adversary you're intending to address but is still a
consequence. Unless I'm reading your proposal incorrectly.

How might the possible threat be addressed. Perhaps a more robust
implementation of network coding and a revisit of circuit length. I'm
just throwing out thoughts. I too am interested in the application of
network coding to the goals of Tor. I'll be eagerly awaiting your
results. Good luck and thanks.

-- leeroy

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