On Nov 11, 2013, at 6:28 PM, Peter Gutmann <pgut...@cs.auckland.ac.nz> wrote:
> Warren Kumari <war...@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. Ok, cute, thank you -- still suffers from the "I take a photo of the object, then blow it up. Three weeks later I print out the photo and take a photo of the victim in front of it" attack, but I like the idea... > 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. Yeah, this seems like the best -- I make a video showing an interaction of the victim with the random strangers and then kill the strangers. The interaction part mitigates the "take a photo and then place victim in front of printout" attack. I'm assuming a *very* evil villain, whose primary weakness are an inability to use photoshop / Gimp and a flair for overly complex plots. He has, however read Peter's Evil Overlord List - http://www.eviloverlord.com/lists/overlord.html W > > Peter. > -- "Go on, prove me wrong. Destroy the fabric of the universe. See if I care." -- Terry Prachett _______________________________________________ cryptography mailing list cryptography@randombit.net http://lists.randombit.net/mailman/listinfo/cryptography
