“Where is Waldo?”, or “Security by Origami”
This is an interesting excersize in security:
A friend of mine gave me a riddle this morning regarding “Where’s Waldo?”. The riddle is as follows:
You and a friend play “Where’s Waldo?”. You solve the puzzle before your friend, and you want to prove to your friend you solved the puzzle, without giving him any hints. How do you do this?
Zero knowledge? Geographic descriptions? Riddles? Hashes?
How do you let your friend know that you solved it, without helping out? What is your solution to this problem? Be creative and leave comments.
Math not required (please) but allowed (if you must).