[tor-bugs] #17799 [Core Tor/Tor]: Use a better PRNG unless OpenSSL starts using a better one on their own.

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#17799: Use a better PRNG unless OpenSSL starts using a better one on their own.
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  nickm
     Type:  defect                               |         Status:  closed
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  unspecified
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  unspecified
 Severity:  Normal                               |     Resolution:
 Keywords:  tor-relay, tor-client, prng,         |  worksforme
  crypto, review-group-34                        |  Actual Points:  5
Parent ID:                                       |         Points:  5
 Reviewer:  asn                                  |        Sponsor:
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Changes (by nickm):

 * status:  new => closed
 * resolution:   => worksforme


Comment:

 > Nick also told me something about future OpenSSL releases changing their
 RNG algorithm too, but I could't find info about this...

 From the OpenSSL 1.1.1 changelog:

 {{{
   *) Grand redesign of the OpenSSL random generator

      The default RAND method now utilizes an AES-CTR DRBG according to
      NIST standard SP 800-90Ar1. The new random generator is essentially
      a port of the default random generator from the OpenSSL FIPS 2.0
      object module. It is a hybrid deterministic random bit generator
      using an AES-CTR bit stream and which seeds and reseeds itself
      automatically using trusted system entropy sources.

      Some of its new features are:
       o Support for multiple DRBG instances with seed chaining.
       o Add a public DRBG instance for the default RAND method.
       o Add a dedicated DRBG instance for generating long term private
 keys.
       o Make the DRBG instances fork-safe.
       o Keep all global DRBG instances on the secure heap if it is
 enabled.
       o Add a DRBG instance to every SSL instance for lock free operation
         and to increase unpredictability.
      [Paul Dale, Benjamin Kaduk, Kurt Roeckx, Rich Salz, Matthias St.
 Pierre]
 }}}

 So yeah, I think it's fine for us to drop this.  No worries; I had fun
 writing the code, but I don't need to maintain it forever.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17799#comment:69>
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