[tor-bugs] #10969 [Core Tor/Tor]: Set of guard nodes can act as a linkability fingerprint

Tor Bug Tracker & Wiki blackhole at torproject.org
Tue Sep 12 20:32:39 UTC 2017

#10969: Set of guard nodes can act as a linkability fingerprint
 Reporter:  asn                                  |          Owner:
                                                 |  mikeperry
     Type:  defect                               |         Status:  closed
 Priority:  High                                 |      Milestone:  Tor:
                                                 |  unspecified
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:  fixed
 Keywords:  tor-client, tor-guard, XKEYSCORE,    |  Actual Points:
  prop259, SponsorU-deferred, QUICKANT           |
Parent ID:                                       |         Points:  large
 Reviewer:                                       |        Sponsor:
Changes (by isis):

 * status:  reopened => closed
 * resolution:   => fixed


 Replying to [comment:36 cypherpunks]:
 > Btw, did anything actually change between asn commenting "switching to
 one entry guard slightly improved the situation, but did not fix the
 issue. The new guard design did not fix the issue either." and nickm
 closing the issue with "Prop271 and its predecessors have made progress

 Yeah, there were several iterations of the new guard algorithm.
 [https://github.com/isislovecruft/guardsim Nick and I simulated several of
 the designs], and the simulations show a substantial improvement towards
 limiting the number of guards used.  If you need higher protections on a
 global passive adversary tracking your physical location at this time,
 consider using [https://github.com/isislovecruft/tordyguards something
 which rotates your state file depending on which network you connect to],
 or using a single bridge relay.  Please also keep in mind that your
 computer likely has numerous other fingerprints which a global passive
 adversary may use to track you, e.g. idiosyncrasies in your networking
 stack, kernel, times that networked cronjobs are executed, etc.

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/10969#comment:39>
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