[tor-bugs] #17694 [Tor]: Hash PRNG output before use, so that it's not revealed to the network

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#17694: Hash PRNG output before use, so that it's not revealed to the network
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 Reporter:  teor         |          Owner:
     Type:  enhancement  |         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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Changes (by nickm):

 * status:  needs_information => needs_revision


Comment:

 Okay, I still think I'm right, but after an IRC discussion with ioerror,
 I'm a bit concerned about the number of smart cautious people who disagree
 with me.

 I think our best move forward here is:
   * Never do anything raw with the system entropy, except feeding it into
 a PRNG or a hash.
   * Whenever the PRNG might be exposed, hash it first.  Split
 crypto_rand() into crypto_rand() and crypto_rand_exposed().
   * Amend specifications with a note on PRNG usage, describing the above.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17694#comment:8>
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