[tor-bugs] #17591 [Tor]: Use channel padding to obscure circuit setup

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#17591: Use channel padding to obscure circuit setup
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     Reporter:  mikeperry    |      Owner:  mikeperry
         Type:  enhancement  |     Status:  new
     Priority:  Medium       |  Milestone:
    Component:  Tor          |    Version:
     Severity:  Normal       |   Keywords:  mike-can
Actual Points:               |  Parent ID:
       Points:               |    Sponsor:
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 We could use the code from #16861 to pad more often during circuit setup
 to defend against circuit fingerprinting by someone who is watching the
 guard node. This would be somewhat complicated, as it would need special
 timers that could be called more often than once per second (or could
 chain off eachother), but it could be done.

 On the client side, it could be done from any of the onionskin or circuit
 launching calls. On the relay side, we probably would need some logic
 around padding more often so long as we're still getting RELAY_EARLY
 cells, or similar.

 It's also debatable in general as to if circuit fingerprinting is still
 successful if you're just watching the guard. If it's not, this may not be
 worth doing (since it won't protect anyone from a malicious or compromised
 guard).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17591>
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