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Re: Template language for random string generation

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From Ian Kelly <ian.g.kelly@gmail.com>
Date Sun, 10 Aug 2014 10:38:16 -0600
Subject Re: Template language for random string generation
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On Aug 10, 2014 6:45 AM, "Devin Jeanpierre" <jeanpierreda@gmail.com> wrote:
> > * Uses SystemRandom class (if available, or falls back to Random)
>
> This sounds cryptographically weak. Isn't the normal thing to do to
> use a cryptographic hash function to generate a pseudorandom sequence?

You mean in the fallback case, right?  I'm no crypto expert, but I've never
heard of SystemRandom being contra-recommended for crypto, and even the
Python docs recommend it.

The output of even a cryptographically strong hash isn't going to have any
more entropy than the input, so if the input is predictable then the output
will be also.  One approach I'm aware of, which is used by Django, is to
hash the RNG state along with the time and a local secret In order to
reseed the RNG unpredictably whenever randomness is required. That creates
a configuration burden in order to establish the secret, though.

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Thread

Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-08 02:01 -0700
  Re: Template language for random string generation Chris Angelico <rosuav@gmail.com> - 2014-08-08 19:22 +1000
    Re: Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-08 02:42 -0700
      Re: Template language for random string generation Ned Batchelder <ned@nedbatchelder.com> - 2014-08-08 07:20 -0400
        Re: Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-08 06:02 -0700
      Re: Template language for random string generation Chris Angelico <rosuav@gmail.com> - 2014-08-08 21:29 +1000
        Re: Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-08 06:03 -0700
  Re: Template language for random string generation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-09 00:08 +1000
  Re: Template language for random string generation Skip Montanaro <skip@pobox.com> - 2014-08-08 09:35 -0500
    Re: Template language for random string generation cwolf.algo@gmail.com - 2014-08-08 11:43 -0700
      Re: Template language for random string generation Nick Cash <nick.cash@npcinternational.com> - 2014-08-08 20:28 +0000
  Re: Template language for random string generation Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-08 16:03 -0600
    Re: Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-08 23:52 -0700
      Re: Template language for random string generation Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-09 01:49 -0600
      Re: Template language for random string generation Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-09 01:57 -0600
  Re: Template language for random string generation Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-08-10 05:43 -0700
    Re: Template language for random string generation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-11 02:31 +1000
      Re: Template language for random string generation Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-08-10 11:28 -0700
        Re: Template language for random string generation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-11 12:22 +1000
          Re: Template language for random string generation Chris Angelico <rosuav@gmail.com> - 2014-08-11 12:31 +1000
          Re: Template language for random string generation Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-08-11 00:01 -0700
      Re: Template language for random string generation Chris Angelico <rosuav@gmail.com> - 2014-08-11 05:25 +1000
      Re: Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-10 22:06 -0700
        Re: Template language for random string generation Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-11 08:58 +0100
    Re: Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-10 09:34 -0700
      Re: Template language for random string generation Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-10 10:47 -0600
        Re: Template language for random string generation Paul Wolf <paulwolf333@gmail.com> - 2014-08-10 21:56 -0700
      Re: Template language for random string generation Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-08-10 11:48 -0700
  Re: Template language for random string generation Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-10 10:38 -0600

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