[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 yawning):

 Replying to [comment:4 nickm]:
 > See the second patch on my branch. :)

 Spiffy.  Minor quibble with the code, don't use KECCAK_MAX_RATE like that
 (Yeah, I should have renamed it/hid it).  Since you're instantiating
 SHAKE128, `KECCAK_TARGET_TO_RATE(128)` is what you want (Or 168, which is
 the SHAKE128 rate in bytes).

 It'll still work, but you're lowering your security level.  My improved
 version of the branch will be more opaque to avoid this confusion/pitfall
 and provide shake128_init/absorb/squeeze/free functions.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17799#comment:5>
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