gpg: failed to create temporary file '/var/lib/lurker/.#lk0x56d4b100.hantslug.org.uk.11030': Permission denied
gpg: keyblock resource '/var/lib/lurker/pubring.gpg': Permission denied
gpg: Signature made Wed May 14 23:12:09 2008 BST
gpg: using DSA key 20ACB3BE515C238D
gpg: Can't check signature: No public key
On Wed, May 14, 2008 at 09:56:01PM +0000, Nick Chalk wrote:
> Peter Alefounder <p_alefounder@???> wrote:
> > Why are pseudo-random numbers used anyway? Is it
> > beyond the wit of man to devise a bit of
> > hardware that would produce genuine random
> > numbers?
>
> What is a "genuine" random number?
>
> I browse a cryptography mailing list. A while ago,
> there was a long, heated, and highly mathematical
> debate on what exactly constitutes randomness, and
> how to test for it. It appears that there is no
> definite answer to either question, even from
> noted researchers in the field.
It's obviously a difficult problem because Knuth had an entire
chapter (large chunks of one volume) on the generation of
pseudo-random numbers in The Art of Computer Programming. :)
> > I am not an electronic engineer, but I
> > understand that a Zener diode can be used to
> > generate white noise.
>
> True - RF noise figure meters use wideband noise
> diodes to generate a test signal. They're
> exceedingly expensive, though, and need a highly
> stable bias voltage to operate.
>
> As Hugo noted, there are some ICs that incorporate
> noise sources - I suspect they use some variant on
> the biased diode technique. The difficulty in the
> design, I expect, is keeping the bias and output
> signal clean. It's no good making a wideband white
> noise source if your output signal contains
> interference from the decidedly non-random clocks,
> and buses.
The VIA one claims to use "frequency variations in a group of
unlocked oscillators". I know almost nothing about electronics, so I
won't claim to understand what that means in practice. :)
Interestingly, pictures of the latest ERNIE (premium bond number
generator) show little other than what looks like a standard ATX PC
motherboard. I suspect that they may be using a board with a
430-series Intel chipset on it. The HRNG on those systems is very
slow (<100 bits/sec) compared to the VIA ones (Mb/s in bursts -- don't
know what the sustained rate is).
Hugo.
--
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
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