[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: 0.2.7.x-final
Component:  Tor          |        Version:  Tor: unspecified
 Severity:  Normal       |     Resolution:
 Keywords:               |  Actual Points:
Parent ID:               |         Points:
  Sponsor:               |
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Comment (by cypherpunks):

 Now the build on precise is failing with
 {{{
 ../src/common/crypto.c: In function 'crypto_strongest_rand':
 ../src/common/crypto.c:2530:1: error: stack protector not protecting local
 variables: variable length buffer [-Werror=stack-protector]
 cc1: all warnings being treated as errors
 }}}

 It looks like using `SHA512_DIGEST_LENGTH` indirectly isn't working. Why
 wasn't it used directly? And why is `SHA512_DIGEST_LENGTH` used while the
 rest of the Tor code base uses `DIGEST512_LEN`?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17694#comment:22>
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