[tor-bugs] #6232 [Analysis]: Make entropy-over-time graph

Tor Bug Tracker & Wiki torproject-admin at torproject.org
Thu Jul 5 10:07:54 UTC 2012


#6232: Make entropy-over-time graph
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 Reporter:  arma         |          Owner:              
     Type:  enhancement  |         Status:  needs_review
 Priority:  normal       |      Milestone:              
Component:  Analysis     |        Version:              
 Keywords:               |         Parent:              
   Points:               |   Actualpoints:              
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Comment(by robgjansen):

 Diversity has 2 dimensions: bandwidth and location. We should capture
 both.

 '''Bandwidth diversity''' means how likely each relay will be chosen based
 on Tor's current bandwidth-weighting scheme. Highest bandwidth diversity
 means each relay is chosen with the same probability.

 '''Location diversity''' means how likely a relay belongs to a specific
 geographic authoritative entity. Highest security means that each
 geographic authoritative entity controls the same number of relays.

 When analyzing the '''actual diversity of a given Tor network''' (i.e.
 consensus), we should include both bandwidth and location. One way to do
 this is to use entropy of bandwidth per authoritative location. For
 example, we can split the Internet into location (i.e. countries or ASes)
 and add up all the bandwidth for the relays in that location. Then, we can
 compute the entropy for each location.

 Now since entropy alone probably lacks meaning in terms of diversity, we
 would also like to know the '''maximum diversity of a given Tor network'''
 (i.e. consensus) we could ever hope to obtain (under this analysis
 approach). This can be computed by taking the total bandwidth in the
 consensus or some other interval and equally distributing it to all
 locations. Then compute the entropy of each location, and sum them to find
 the maximum diversity of the network during that consensus or interval.

 Finally, we quantify the '''degree of diversity of the network''' during
 an interval as the current diversity divided by the maximum diversity
 during that Interval. This will allow us to know how close to optimal we
 currently are. The current diversity and maximum diversity entropy graphs
 are probably also useful.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6232#comment:12>
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