[tor-bugs] #20012 [Core Tor/Tor]: Stop upgrading client to intro connections to ntor

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#20012: Stop upgrading client to intro connections to ntor
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  teor
     Type:  defect                               |         Status:
                                                 |  merge_ready
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.2.9.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tor-hs, TorCoreTeam201608, review-   |  Actual Points:  0.2
  group-8                                        |
Parent ID:                                       |         Points:  1
 Reviewer:                                       |        Sponsor:
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Comment (by teor):

 Replying to [comment:3 andrea]:
 > This looks okay to merge; I am curious under what circumstances an HS
 learning which consensus version a client has could be a realistic attack
 though?

 I'm not sure it's a realistic attack by itself, but it does reduce the
 anonymity set of clients: since there are 72 (or is it 75? or more if
 their clock is slow?) possible consensuses a client could be using, this
 is a significant distinguisher. (Clients should be using one of ~3 recent
 consensuses if they can download one.)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20012#comment:4>
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