[tor-bugs] #25756 [Core Tor/Tor]: EARLY_CONSENSUS_NOTICE_SKEW of 60 is too strict for some drifting dirauth clocks

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#25756: EARLY_CONSENSUS_NOTICE_SKEW of 60 is too strict for some drifting dirauth
clocks
-------------------------------------------------+-------------------------
 Reporter:  Dbryrtfbcbhgf                        |          Owner:
                                                 |  catalyst
     Type:  defect                               |         Status:
                                                 |  assigned
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.4.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.3.2.10
 Severity:  Normal                               |     Resolution:
 Keywords:  clock-skew, s8-errors, 034-roadmap-  |  Actual Points:
  proposed                                       |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
                                                 |  Sponsor8-can
-------------------------------------------------+-------------------------

Comment (by catalyst):

 From dir-spec.txt:
 {{{
    VA-DistSeconds-VoteSeconds: The authorities exchange votes.

    VA-DistSeconds-VoteSeconds/2: The authorities try to download any
    votes they don't have.

    VA-DistSeconds: The authorities calculate the consensus and exchange
    signatures.

    VA-DistSeconds/2: The authorities try to download any signatures
    they don't have.

    VA: All authorities have a multiply signed consensus.
 }}}
 So `VA-DistSeconds` is the earliest that a dirauth with a skewed clock
 could possibly release a valid consensus, assuming that the other dirauths
 don't have skewed clocks.  We probably shouldn't decide that a consensus
 is "early" before that time.  (We probably should add some tolerance as
 well.)

 If multiple dirauths have skewed clocks the story gets more complicated.
 Maybe it'll be rare enough to avoid thinking about for now?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25756#comment:17>
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