[tor-bugs] #25381 [Core Tor/Tor]: Add crypto_rand_double_sign() in C and Rust

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#25381: Add crypto_rand_double_sign() in C and Rust
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     Reporter:  teor          |      Owner:  teor
         Type:  enhancement   |     Status:  assigned
     Priority:  Medium        |  Milestone:  Tor: 0.3.4.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:  tor-relay, privcount
Actual Points:                |  Parent ID:  #23061
       Points:  2             |   Reviewer:
      Sponsor:  SponsorQ      |
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 We need a function that returns 1.0 or -1.0 with equal probability, so we
 can avoid weird tricks that waste floating point precision.

 Since we want to use this in the laplace and guassian distributions, it
 needs to be implemented in both C and Rust.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25381>
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