[tor-bugs] #16297 [Tor]: Reduce Sybil harm while still getting use out of them

Tor Bug Tracker & Wiki blackhole at torproject.org
Mon Jun 8 19:52:01 UTC 2015


#16297: Reduce Sybil harm while still getting use out of them
-----------------------------+-------------------
     Reporter:  phw          |      Owner:  phw
         Type:  enhancement  |     Status:  new
     Priority:  normal       |  Milestone:
    Component:  Tor          |    Version:
   Resolution:               |   Keywords:  sybil
Actual Points:               |  Parent ID:
       Points:               |
-----------------------------+-------------------

Comment (by arma):

 Does the Valid flag still do what it used to do?

 That is, unless something changed, we have a substantial amount of this
 infrastructure in place, in that clients already know how to avoid nodes
 the lack the Valid flag for the entry or exit point.

 The HSDir part is tricky, first because I don't think Valid has much to do
 with it in its current definition, and second for the reason Nick points
 out, that our past definition of 'not valid' didn't consider HSDir a
 threatening role, so odds are good we'll miss some future similar case.
 It's not that tricky though since auths could choose to stop voting HSDir
 for a relay if they don't vote Valid for it.

 The DirPort one might be a bit trickier, since I don't think we have a
 "voting" procedure in the consensus about whether to list a dirport for a
 given relay or not. Rather, it's a deterministic process based on what the
 (signed) relay descriptor says. We could teach clients not to use inValid
 relays for directory questions, but that will splinter the anonymity sets.
 We could note that proper clients use directory guards, which have the
 Guard flag, and thus have the Valid flag, so we accidentally already
 solved it. Or we could make a new consensus method to put a '0' into the
 consensus instead of the dirport for inValid relays.

 So, in summary, let's use AuthDirInvalid and !invalid more often?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16297#comment:2>
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