Kryptos' final code remains unsolved. The CIA sculpture's creator is auctioning the solution

BOSTON (AP) — When Jim Sanborn was commissioned to create a sculpture at CIA headquarters, he wanted to do something that spoke to its world of spies and secret codes.

The result was a 10-foot-tall, S-shaped copper screen called Kryptos that resembles a piece of paper coming out of a fax machine. One side features a series of staggered alphabets that are key to decoding the four encrypted messages on the other side.