Warren Kumari <warren@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.