[tor-bugs] #17799 [Tor]: Hash All PRNG output before use

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#17799: Hash All PRNG output before use
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 Reporter:  teor    |          Owner:
     Type:  defect  |         Status:  needs_revision
 Priority:  Medium  |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor     |        Version:  Tor: unspecified
 Severity:  Normal  |     Resolution:
 Keywords:          |  Actual Points:
Parent ID:          |         Points:
  Sponsor:          |
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Comment (by nickm):

 I think their performance is likely to be worse, but their space usage is
 likely to be better.  If I'm doing the math right, and we're using
 SHAKE-128 or equivalent, and we assume that we want to have 2^256^
 security against backtracking attacks, I get 166.7 bytes per Keccak-f call
 with 4K memory usage, and they get 152 bytes,with somewhere between 200
 and 400 bytes of memory usage.

 (I'm also assuming that reseed events are comparatively uncommon.  If
 that's wrong, oops!)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17799#comment:10>
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