[cryptography] NIST Randomness Beacon

Warren Kumari warren at kumari.net
Mon Nov 11 12:26:33 EST 2013

On Nov 10, 2013, at 3:15 AM, andrew cooke <andrew at acooke.org> wrote:

> the idea of a service that provides data unknown before a certain date (like a
> photo of a recent newspaper) was suggested here -
> http://rachelbythebay.com/w/2012/08/29/info/

Ok, so the "take a photo of the victim with todays newspaper" is a common (and fairly clever) kidnapping movie trick.
Presuming the kidnappers / attackers cannot use photoshop, this sets an *earliest* timestamp for an event[0].

I've often wondered if there is a clever way to do the inverse -- basically to have a "latest" timestamp? This seems like a much harder problem -- 'm looking for a "movie plot" type solution that the public can easily understand…

The best solution I've heard so far (assuming, just like the kidnapping scenario that the attacker doesn't know how to use photoshop!) is to take the photo outside, at night with a number of celestial bodies in the frame… 
Another solution is to take the photo / proof at a large, well documented and difficult to recreate event -- something like a presidential inauguration ceremony, large concert, etc.

Anyone have any other cute tricks?

And no, I don't actually need a solution here, it's just a thought experiment...

[0]: It's not an actual timestamp, I could e.g take a photo of the newspaper from April 1912 to "prove" I was alive when the Titanic sank :-).

> for fun, i implemented that here - http://colorlessgreen.net/ (the random
> value is updated every 50000 secs, roughly, and encoded as a "memorable
> phrase")
> of course, in this case, a PRNG was used, and i am not NIST (so i am not
> guaranteeing unpredictability ot autonomy to the same extent!), and the output
> is only ~50 bits in size.
> as far as i know, no-one uses it for anything...
> andrew
> On Sat, Nov 09, 2013 at 08:28:17PM -0800, d.nix wrote:
>> surely someone here has an opinion...
>> http://www.nist.gov/itl/csd/ct/nist_beacon.cfm
>> :-)
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The above email is neither interesting or relevant, but at least it provided no new information.

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