On Thu, 15 May 2008, Timothy Murphy wrote:
> My impression is that while random number generation based on
> quantum theory sounds a nice idea, in practice a mathematical
> pseudo-random number generator is probably much more reliable, and
> certainly much simpler.
>> By definition, it is impossible to test if a source is random; What
> reason do you have to suppose your "Zener approach" (which I didn't
> really understand) produces random output?
>> I haven't seen any evidence that intelligently designed
> pseudo-random number generators have ever caused any problem.
> Personally, I'd trust Knuth much more than any DIY device.
Trust a mathematician to put their faith in the abstract over the
I don't have my Knuth handy to be more specific, but my (terribly
bad) memory of it is:
- He details some of the tests that exist to detect patterns and help
detect non-random data.*
- The Knuth work describes PRNG techniques that are seriously old
(50s or 60s) - I've got this nagging voice in my head that says
that those PRNGs, that were once state-of-the-art, have long been
found to have weaknesses, but I dont know for certain.
If we can't determine randonmess, why should trust the output of a
man-made algorithm that /seems/ random over measurements of physical
processes that we apparently have good reason to believe /are/
Just evolutionary advances in one field would be enough to render
those PRNGs flawed, while it would need major, revolutionary advances
in the other to undermine the empirical, physical-process based RNGs.
* And methinks all PRNGs, such as the openssl one, should constantly
self-test their output in this way. Perhaps then it wouldn't have
taken nearly 2 years to detect that Debian was shipping a getpid()
** The engineering to measure things seems less hard than the math,
to me anyway.
Paul Jakma paul at clubi.iepaul at jakma.org Key ID: 64A2FF6A
An engineer is someone who does list processing in FORTRAN.
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