[tor-bugs] #4900 [Tor Relay]: Use a more randomized hash function for our hash tables

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#4900: Use a more randomized hash function for our hash tables
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 Reporter:  nickm         |          Owner:                    
     Type:  defect        |         Status:  new               
 Priority:  normal        |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Relay     |        Version:                    
 Keywords:  dos security  |         Parent:                    
   Points:                |   Actualpoints:                    
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 (This is NOT about using a new cryptographic hashing algorithm.)

 There's been some good work recently [1] about the class of DOS attacks
 where you know the hash algorithm that's going to be used for putting data
 into a hash table, so you provide a whole bunch of known-to-collide inputs
 so that the hashtable operations will become O(N) rather than O(1).

 To avoid this class of attacks, we ought to have some sort of a per-run
 random tweak on the data-hashing functions we use for our hash tables.

 [1] http://events.ccc.de/congress/2011/Fahrplan/events/4680.en.html

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4900>
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