I'm very curious as to how humans can directly decode encrypted pictures. Do they stare at it for 10 minutes and go "ah, there it is". ... About 10 years ago there was a Scientific American article about visual encypherment. The decoder required no computing hardware. A one time pad was available at both ends in the form of an array of 1000 by 1000 random black or white pixels in the form of a transparency. When it was time to code a black and white image an array of pixels were produced with each

At 10:07 5/11/94 -0700, Paul E. Baclace wrote: pixel being black with a probility proportional to the darkness at that point of the 'plain-image'. That was exclusive ored with the one time pad. This yielded a random set of black and white pixels and was transmitted physically by insecure courrier. It it reached the destination it would ideally be exclusive ored with the other copy of the one time pad. The receiver could more easily align the cypher-image with the one time pad and see a fairly good image. This yields the 'and' function in place of the 'xor' and provides about half of the image quality in the information theortic sense.