[onerng talk] Chaoskey presentation at LCA2017
iang
iang at iang.org
Sat Jun 17 09:15:30 BST 2017
Understood what you're asking for but actually it is impossible or
impractical.
There is no test that can say something is random. There is a test that
says, I can't see pattern X. And there are tests that say we can't see
patterns X-Z. That's because of the nature of randomness - it can't be
predicted therefore you can't predict that it wasn't created.
In more practical terms, take a psuedorandom generator like a cipher,
and just feed it your known password. The result is psuedo-random - it
is guaranteed to show no pattern. But it's not random because it is
reproducible by anyone who knows the password. E.g., a "RNG" could be
built with a cipher and the key "NSABACKDOOR" and it would always appear
random but be precisely non-random.
So how do we solve this problem in practice? We solve it by (a ) using
multiple sources that are not visible to the same attacker, then (b)
feeding each uncorrelated source into a "mixer" and (c) feeding the
output of that into a psuedo-random-number-generator, which generates
RNs for the user.
http://iang.org/ssl/hard_truths_hard_random_numbers.html
OneRNG the provides a great source to that end, as in practical systems
we mostly have poor RNGs in the operating system but we can mix in
additional entropy.
iang
On 14/06/2017 19:35, bsr wrote:
> Post by bsr: Chaoskey presentation at LCA2017: OneRNG Talk: OneRNG
> OneRNG <http://lists.onerng.info>
>
> Photo of bsr <http://lists.onerng.info/p/bsr>
> *Chaoskey presentation at LCA2017*
> <http://lists.onerng.info/r/topic/2fWDsknCPfL2tqPTVsVmlU>
> by *bsr* <http://lists.onerng.info/p/bsr>
> in *OneRNG Talk* <http://lists.onerng.info/groups/onerng-talk>
>
> ------------------------------------------------------------------------
> Very good presentation but I found Keith's comments about testing for
> randomness a bit disconcerting, specifically how the noisy but
> non-random image containing Pi passes DieHarder testing. When I look
> at the noisy image on the right I see three dots with three vertical
> traces and also a weak horizontal line, although he says there are two
> dots. The point is that the image is clearly not random upon a quick
> visual inspection and yet he says when he ran the image through
> DieHarder it said, "Oh yes, that's completely random". Are there any
> other (better?) software tools that exist for testing/verifying
> randomness? It seems to me that this a catch-22. Short of building
> another hardware entropy generator that we accept as truly random (a
> reference standard to compare against) how can we verify true
> randomness? And how would we know our chosen rng standard is truly
> random to begin with? It seems hardware measuring decay would be truly
> random but I'm dubious about a fish tank standard - my black skirt
> tetras are quite territorial ;)
>
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