[tor-bugs] #30092 [Core Tor/Tor]: Add a probability-to-apply field for circuitpadidng machines

Tor Bug Tracker & Wiki blackhole at torproject.org
Mon Apr 22 11:13:08 UTC 2019


#30092: Add a probability-to-apply field for circuitpadidng machines
-------------------------------------------------+-------------------------
 Reporter:  mikeperry                            |          Owner:  (none)
     Type:  enhancement                          |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.4.1.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  wtf-pad, tor-relay, tor-cell,        |  Actual Points:  0.5
  padding, 041-proposed                          |
Parent ID:  #28634                               |         Points:  2
 Reviewer:  asn                                  |        Sponsor:
                                                 |  Sponsor2-can
-------------------------------------------------+-------------------------

Comment (by asn):

 BTW as a more general comment in this ticket, we should think a lot before
 we use this feature because the overhead danger is high (depending on the
 probability) and reaping the benefits is not always as straightforward.

 For example, consider using this feature for ticket #28634 to make general
 circuits look more random and blend in with random-lookin HS circuits. In
 that case, it's true that we increase the false positive rate of
 identifying a single intro or rend circuit, but if you look at the whole
 HS circuit dance, you can see that an HS client starts using 2 circuits at
 the same time (intro and rend, let's ignore hsdir for now). This ticket
 won't make normal clients start using 2 circuits at once, so even tho a
 single circuit might look random if the `probability` triggers, the fact
 that it's missing the second circuit  might still act as an identifier in
 that the session is not actually an HS dance and it's faking it.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/30092#comment:7>
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