[cryptography] NIST Randomness Beacon

[Peter Gutmann]

Warren Kumari <warren at kumari.net> writes:

>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…

You could do it with a physical one-way function.  Take a photo of the victim
on top of the WTC and you know that it can't have been occurred after 9/11. To
generalise it, photograph the victim in front of some documented object and
then destroy the object.  I'm assuming in the movie-plot scenario that someone
who's kidnapped a victim won't worry about blowing up a statue in a park or
performing whatever the physical one-way operation is.  Depending on how evil
your movie-plot villain is (and how convoluted the plot will get), he/she
could kill random strangers after photographing them with the victim, in order
to fix a point in time.

Peter.