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

Tor Bug Tracker & Wiki blackhole at torproject.org
Thu Sep 14 22:44:22 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:

Comment (by teor):

 Replying to [comment:42 isis]:
 > Replying to [comment:41 cypherpunks]:
 > > Replying to [comment:40 cypherpunks]:
 > > > Hi isis, I'm again reopening this ticket because the fundamental
 problem in the title and description ("set of guard nodes can act as a
 linkability fingerprint") remains unfixed.
 > > > I just checked a friend's laptop (Debian stable, tor and when it got online it immediately connected to four
 guards. I don't know why, but I suspect it's because (like most laptops)
 it is sometimes not connected to the internet. (Some time later, it
 remained connected to two of them.)
 > >
 > > Sorry but that doesn't disprove what Isis said, Prop271 was
 implemented in Tor 0.3.0.x and not 0.2.9.x which your laptop's friend had.

 It is likely that at least 2 of the 4 "guards" are:
 * directory authorities
 * fallback directory mirrors
 * directory guards

 That's why your client disconnected from 2 of them after downloading the
 consensus, certificates, and descriptors.

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/10969#comment:43>
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