[tor-bugs] #2653 [Tor]: Support more stable guards for live CDs

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#2653: Support more stable guards for live CDs
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 Reporter:  nickm        |          Owner:                  
     Type:  enhancement  |         Status:  new             
 Priority:  normal       |      Milestone:  Tor: unspecified
Component:  Tor          |        Version:                  
 Keywords:  tor-client   |         Parent:                  
   Points:               |   Actualpoints:                  
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Comment(by rransom):

 Replying to [comment:1 rransom]:

 > > One (approximate) solution is to pick guard nodes based on the first N
 nodes sorted by H(Seed|NodeID).  This doesn't do weighting correctly,
 though.
 >
 > We can do weighting by computing H(GuardID | 0), H(GuardID | 1), ...,
 H(GuardID | !GuardWeight - 1) for each guard, and then choosing the
 closest guard to H(Seed | 0), the closest not-yet-chosen guard to H(Seed |
 1), and so on.
 >
 > Further improvements are needed to make GuardIDs seed-dependent, make
 each guard's GuardID change at pseudo-random times, and possibly make each
 guard-selection value (the H(Seed | i) above) change at pseudo-random
 times as well.

 ‘Simultaneous rational approximation’ of the selection-probability
 distribution might make the performance of this technique somewhat less
 horrific.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/2653#comment:11>
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