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Re: Exhausted

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On Thu, 17 Mar 2016 10:34:03 +1000, John Larkin  
<jjlarkin@highlandtechnology.com> wrote:

> On Wed, 16 Mar 2016 17:17:46 -0700, dplatt@coop.radagast.org (Dave
> Platt) wrote:
>
>> In article <epsjeb928pv3n7d6m4j583t8fnmbbrjsad@4ax.com>,
>> John Larkin  <jjlarkin@highlandtechnology.com> wrote:
>>
>>> I wonder if there is a public random data generator somewhere on the
>>> internet. You could use ping times or something as a source of
>>> randomness.
>>
>> I think you'd find that the entropy available from ping times is
>> rather poor.  There are more sources of correlation than you might  
>> expect.
>>
>>> Any online webcam should provide a lot of noise.
>>
>> One classic approach was to aim a webcam at a Lava Lamp, or one of the
>> similar amusements that were filled with a glitter-loaded liquid.
>> Taking two frames several seconds apart, and calculating the
>> difference, produced some reasonably decent entropy.
>
> A busy city street scene should be pretty noisy. Any camera will have
> lots of per-pixel noise, and lots of pixels.
>
>>
>> Getting really *good* random entropy is surprisingly difficult,
>> especially if you're concerned about having it *stay* random in the
>> face of attacks, outside interference, "pulling", etc. which can make
>> it more predictable.
>
> If you have a long-length (say, something like 256 bits) pseudo-random
> number generator, you can mush in some external randomness source
> (like a webcam, a sound card, a ring oscillator, whatever) and make it
> randomly jump all around its state sequence. Do that 64 times with
> different register lengths and noise sources and xor.
>
>
>

Digitizing screen shots of an aquarium would provide the same thing - just  
don't try to save on hardware by digitizing a screen saver.

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Exhausted  "David Eather" <eather@tpg.com.au> - 2016-03-16 15:53 +1000
  Re: Exhausted Klaus Kragelund <klauskvik@hotmail.com> - 2016-03-16 01:07 -0700
  Re: Exhausted George Herold <gherold@teachspin.com> - 2016-03-16 06:04 -0700
    Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-17 00:16 +1000
      Re: Exhausted Allan Herriman <allanherriman@hotmail.com> - 2016-03-16 16:35 +0000
        Re: Exhausted George Herold <gherold@teachspin.com> - 2016-03-16 11:15 -0700
          Re: Exhausted Allan Herriman <allanherriman@hotmail.com> - 2016-03-17 12:11 +0000
      Re: Exhausted mrdarrett@gmail.com - 2016-03-17 10:37 -0700
        Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-18 07:25 +1000
          Re: Exhausted mrdarrett@gmail.com - 2016-03-17 15:05 -0700
    Re: Exhausted Winfield Hill <hill@rowland.harvard.edu> - 2016-03-16 07:32 -0700
      Re: Exhausted George Herold <gherold@teachspin.com> - 2016-03-16 08:04 -0700
        Re: Exhausted Winfield Hill <hill@rowland.harvard.edu> - 2016-03-16 08:16 -0700
        Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 10:32 -0700
          Re: Exhausted George Herold <gherold@teachspin.com> - 2016-03-16 11:08 -0700
            Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 12:30 -0700
              Re: Exhausted Clifford Heath <no.spam@please.net> - 2016-03-17 06:47 +1100
                Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 17:01 -0700
                Re: Exhausted Clifford Heath <no.spam@please.net> - 2016-03-17 07:01 +1100
                Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 17:27 -0700
                Re: Exhausted Piotr Wyderski <peter.pan@neverland.mil> - 2016-03-17 17:35 +0100
                Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-17 10:13 -0700
                Re: Exhausted Clifford Heath <no.spam@please.net> - 2016-03-18 11:38 +1100
                Re: Exhausted dplatt@coop.radagast.org (Dave Platt) - 2016-03-16 17:17 -0700
                Re: Exhausted Lasse Langwadt Christensen <langwadt@fonz.dk> - 2016-03-16 17:21 -0700
                Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 17:39 -0700
                Re: Exhausted "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-03-16 21:24 -0500
                Re: Exhausted Phil Hobbs <pcdhobbs@gmail.com> - 2016-03-16 20:51 -0700
                Re: Exhausted George Herold <gherold@teachspin.com> - 2016-03-16 20:21 -0700
                Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 21:16 -0700
                Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 17:34 -0700
                Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-18 07:31 +1000
                Re: Exhausted rickman <gnuarm@gmail.com> - 2016-03-17 00:01 -0400
                Re: Exhausted Clifford Heath <no.spam@please.net> - 2016-03-17 14:09 +1100
                Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-17 09:01 -0700
                Re: Exhausted Piotr Wyderski <peter.pan@neverland.mil> - 2016-03-17 17:46 +0100
                Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-18 07:33 +1000
                Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-18 07:35 +1000
                Re: Exhausted Piotr Wyderski <peter.pan@neverland.mil> - 2016-03-18 11:44 +0100
      low-voltage low-current noise sources Winfield Hill <hill@rowland.harvard.edu> - 2016-03-16 08:10 -0700
  Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-16 08:35 -0700
    Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-18 07:52 +1000
      Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-17 15:35 -0700
        Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-18 09:09 +1000
          Re: Exhausted John Larkin <jjlarkin@highlandtechnology.com> - 2016-03-17 16:54 -0700
          Re: Exhausted George Herold <gherold@teachspin.com> - 2016-03-17 17:40 -0700
            Re: Exhausted mixed nuts <melopsitticus@undulatus.budgie> - 2016-03-17 22:37 -0400
        Re: Exhausted "David Eather" <eather@tpg.com.au> - 2016-03-18 09:09 +1000
        Re: Exhausted George Herold <gherold@teachspin.com> - 2016-03-17 17:29 -0700

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