2001-07-13 02:00:00 UTC
I had an idea some time ago that it would be possibly to create a crossword in which each clue consisted of the answer encrypted. You'd have to decrypt the clues in such a way that they fitted together in the crossword.
Of course, you'd be able to solve the crossword by assuming that each clue was encrypted with a one-time pad, working out any combination of words that fitted the crossword, and working out the pads that would gain the answers you wanted.
It would probably be more effective if you were given the algorithm and if all the clues were encrypted using the same key. It would also help if the algorithm was reasonably weak. Impossible challenges aren't usually very enjoyable.