[tor-dev] Proposal 302: Hiding onion service clients using WTF-PAD

Tom Ritter tom at ritter.vg
Thu May 16 13:36:12 UTC 2019

On Thu, 16 May 2019 at 11:20, George Kadianakis <desnacked at riseup.net> wrote:
>     3) Duration of Activity ("DoA")
>       The USENIX paper uses the period of time during which circuits send and
>       receive cells to distinguish circuit types. For example, client-side
>       introduction circuits are really short lived, wheras service-side
>       introduction circuits are very long lived. OTOH, rendezvous circuits have
>       the same median lifetime as general Tor circuits which is 10 minutes.
>       We use WTF-PAD to destroy this feature of client-side introduction
>       circuits by setting a special WTF-PAD option, which keeps the circuits
>       open for 10 minutes completely mimicking the DoA of general Tor circuits.

10 minutes exactly; or a median of 10 minutes?  Wouldn't 10 minutes
exactly be a near-perfect distinguisher? And if it's a median of 10
minutes, do we know if it follows a normal distribution/what is the
shape of the distribution to mimic?


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