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[tor-bugs] #4900 [Tor Relay]: Use a more randomized hash function for our hash tables
#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
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4900>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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