[Beowulf] OT: public random numbers?

Robert G. Brown rgb at phy.duke.edu
Sat Aug 13 10:51:46 PDT 2011

On Fri, 12 Aug 2011, Leif Nixon wrote:

> On 12 August 2011 17:58, David Mathog <mathog at caltech.edu> wrote:
>> After posting I thought of one other source of more or less random
>> verifiable numbers - the scores of sporting events.  These are not
>> always generated every day, and are seasonal for the various sports.
>> They are however highly verifiable and when multiple events are grouped,
>> pretty much impossible to "fix" to preselected digits.
> Have you looked at RFC3797? Not sure if it has any solutions for you, but it
> at least discusses the same problems.

If people know how you are going to pick the seed of your rng, and know
the rng, and know (or measure) the distribution function from which your
seed is being drawn, they can easily transform the game into a non-zero
sum game with advantage over all of those that don't do all of that.

The only way to avoid this sort of thing is to pick your seed from a
flat, unpredictable distribution.  Unpredictable (in it's purest sense)
includes flat, but the score distribution of almost any sporting event
is, I'm pretty sure, not flat.

That's why I really don't like the idea of running a lottery off of data
like this.  No state lottery could ever be certified on top of this sort
of data.

I'll tell you what.  Piggy back your lottery to theirs.  Powerball games
occur every day all over the US.  Pick your seed from the last 10 digits
of one of those games.  They are announced, publicly available on
websites (I'm pretty sure), and if they aren't certifiably random,
something is seriously wrong.  In any event they are usually generated
from an easily understandable random physical process that is almost
certainly flat as well as unpredictable.

Then pop it into your favorite AES-based or threefish based RNG, or cook
up something yourself with even more rotors, spin it a while, and out
comes your lottery winner -- basically a transmogrification of public
state lottery number, but that's an ADVANTAGE, not a disadvantage...


> -- 
> Leif Nixon                       -            Systems expert
> ------------------------------------------------------------
> National Supercomputer Centre    -      Linkoping University
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Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu

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