Kryptos is not a cipher device, but a sculpture that bears one of the most famous unsolved encrypted messages in the world.
It sits inthe CIA headquarters at Langley, Virginia, and was made by artist Jim Sanborn.
It is comprised of four copper panels, with letters cut out to form the encrypted text.
Around the panels are some rocks, petrified wood, plants, and a small pool of water.
There are also copper slabs with morse code.
The Cipher
The cipher text is made up of 4 parts, dubbed K1 to K4.
The first three have been deciphered before the year 2000, but K4 remains unsolved .