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Re: What happened to radtard?

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On 31/07/15 13:24, Richard Heathfield wrote:
> On 31/07/15 12:07, Paul N wrote:
> 
> <snip>
> 
>> If the data were truly random, you'd expect about
>> the same amount of each byte, so if there is a big
>> difference between the most and least fequent values
>> that would sugest that there's *something* going on.
> 
> That's right. Thing is, "about the same amount of each byte" is a bit
> nebulous, isn't it? I'm not quite sure how to express this, but I want
> to be able to decide, in a binary (yes/no) fashion, whether there's
> *something* going on, in a programmatic or at least numerical way. How
> much something does there need to be (how much departure from a flat
> distribution) before it's *something* rather than just something?
> 

Of course, even with different frequencies for different bytes, it could
be a random process (think of rolling two dice and adding them, for a
simple example).

The first step, I think, would be to draw two graphs - one ordered by
frequency, and one ordered by byte.  That might give you some inspiration.

But without any more information, or a clear outstanding pattern, it's a
lost cause.  There is no way from what you have that you could
distinguish line noise from a gzip'ed Shakespear play.

>> Beyond that, you could compare with the frequencies
>> of letters, to see if it might be a simple substitution
>> cypher (each letter replaced with a particular different one).
> 
> Er, yeah, that's relevant too, I guess, but the day I have trouble
> cracking a simple substitution cipher is the day I hang up my keyboard. :-)
> 

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Thread

What happened to radtard? Chad <cdalten@gmail.com> - 2015-07-31 02:26 -0700
  Re: What happened to radtard? Richard Heathfield <rjh@cpax.org.uk> - 2015-07-31 10:47 +0100
    Re: What happened to radtard? Paul N <gw7rib@aol.com> - 2015-07-31 04:07 -0700
      Re: What happened to radtard? Richard Heathfield <rjh@cpax.org.uk> - 2015-07-31 12:24 +0100
        Re: What happened to radtard? David Brown <david.brown@hesbynett.no> - 2015-08-05 11:08 +0200
          Re: What happened to radtard? Walter Banks <walter@bytecraft.com> - 2015-08-12 14:03 -0400
        Re: What happened to radtard? Paul N <gw7rib@aol.com> - 2015-08-05 15:29 -0700
      Re: What happened to radtard? leif.roar@dimnakorr.com - 2015-08-06 03:31 -0500
  Re: What happened to radtard? fir <profesor.fir@gmail.com> - 2015-07-31 08:10 -0700
    Re: What happened to radtard? Chad <cdalten@gmail.com> - 2015-07-31 23:05 -0700

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