Re: using white noise for cryptography
On Thu, Mar 13, 2003 at 08:14:57PM -0500, Jason Healy wrote:
> At 1047600013s since epoch (03/13/03 19:00:13 -0500 UTC), sean finney wrote:
> > On Thu, Mar 13, 2003 at 11:43:54PM +0100, martin f krafft wrote:
> > > 1. is there already a package that enables this?
> >
> > not that i know of.
>
> While there isn't a package, there is a guy who is doing this on a computer:
>
> http://www.random.org/
>
> Perhaps he'd share his source code?
>
> He also has links to this site:
>
> http://www.cs.berkeley.edu/~daw/rnd/
>
> Which had the following interesting-looking links about audio:
>
> ftp://ftp.dnai.com/users/shipley/audio_rand.tar.gz
> http://www.cs.berkeley.edu/~daw/rnd/audio-entropyd
>
> None of those are white-noise RNG (like the one you described), but
> they may still fit the bill for your needs.
>
"White noise" is a theoretical ideal that is never realized in
practice. White noise is a signal that has the same power level at
every frequency. In any real analog circuit, there is an upper half
power frequency, and in most there is also a lower half power
frequency. In a digital sampler there is also Nyquist folding
frequency, which is half the sampling frequency. You should be
knowledgeable about all this theory before you embark on this project.
But the randomness that is derived from computer OS data logging is
also surely not truly random either. The package that captures entropy
has some fancy footwork to extract good randomness from the raw
data. It should be possible to speed the creation of randomness by
feeding noise data from an analog amplifier into this process, but be
sure you feed it in at the right place. Where is that place? Ask an
expert on the entropy pool stuff in the kernel. Randomness is a tricky
business!
And if you do produce a system that is "theoretically perfect", be
sure to test its output quite thoroughly for randomness before you
make the claim. There have been many embarising failures in this line
of work, and they are not well documented!
Good luck!
--
Paul E Condon
pecondon@quiknet.com
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