[tor-bugs] #22422 [Core Tor/Tor]: Add noise to PaddingStatistics

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#22422: Add noise to PaddingStatistics
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 Reporter:  teor          |          Owner:
     Type:  defect        |         Status:  new
 Priority:  High          |      Milestone:  Tor: 0.3.1.x-final
Component:  Core Tor/Tor  |        Version:  Tor: 0.3.1.1-alpha
 Severity:  Normal        |     Resolution:
 Keywords:  privcount     |  Actual Points:
Parent ID:                |         Points:  0.5
 Reviewer:                |        Sponsor:
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Changes (by teor):

 * cc: robgjansen, amj703 (added)
 * keywords:   => privcount


Comment:

 Replying to [comment:6 mikeperry]:
 > To know how many padding cells to expect for a client, we need
 information on how long an average client's connection lasts,

 Using closed connections to count clients (and also not quite the time
 interval you're after):
 "Tor has about 700 thousand unique clients connecting to the network
 during an average 10-minute interval."

 > how often they make connections during a 24 hour interval,

 "Compared to Tor’s own estimate of about 1.75 million clients per day in
 May 2016..., this suggests that the client population turns over about 2.5
 times a day."

 > and what percentage of the time those connections are idle. Do we have
 this data?

 "Somewhat surprisingly, we found that about 130 thousand clients have in-
 active circuits during an average 10 minutes."

 (That is, closed connections with no circuits with more than 8 cells
 either sent or received.)

 > Also, is there a good example of where we add noise in a way
 successfully calculates how to hide a single client's activity? It would
 be helpful to have a reference to work off of.

 Pages 7-8 of the PrivCount paper give the theory behind differential
 noise.
 I am not sure where to find anything similar in the tor code.
 When we add noise, we've done it inconsistently and arbitrarily in the
 past.

 Perhaps Rob or Aaron can help?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22422#comment:7>
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