Kryptos

Kryptos stands outdoors on the grounds of the George Bush Center for Intelligence, the headquarters of the Central Intelligence Agency in Langley, Virginia. Jim Sanborn built it as a sculpture, a fountain and a ciphertext — a ciphertext being a piece of writing that has been scrambled on purpose, so that only someone who works out the method can read it. The main element is a curved sheet of copper with rows of letters cut clean through the metal. Water runs at its base, among granite, petrified wood and quartz. It was dedicated on 3 November 1990.

The letters are not decoration. They spell out four encrypted passages, and most of the work uses a Vigenère cipher. That cipher works like this. You choose a keyword and write it over and over above your message. Each letter of the keyword tells you how far along the alphabet to push the letter beneath it. A keyword letter of B pushes one place, C pushes two, and so on. Because the keyword keeps changing as it repeats, the same letter in the message turns into different letters in the code, so the usual trick of counting which letters appear most often does not crack it. Here the keyword is Kryptos, the sculpture’s own title, taken from the Greek word for hidden.

Cryptanalysts — people who break codes without being given the key — have read three of the four passages. The fourth has not been read by anyone who has said so publicly. Sanborn has released four clues to it over the years, each narrowing the problem without giving the answer. He has also said that a fifth message will only become available once all four passages have been solved.

As an object, the piece asks for two kinds of looking. Close up, the copper behaves like a page: rows of characters, a text you try to read and cannot. Step to the side and the same sheet is a screen, its cut-out letters holes that let light and air through, so the message reads as solid metal from one side and as gaps from the other. The fountain keeps the site in motion; the sound and the water carry on regardless of whether anyone is any closer to the answer. The stone and wood work at a slower speed. Petrified wood is once-living timber whose fibres have been replaced by mineral over long stretches of time. Quartz is crystal. Granite is rock from deep in the earth. None of them carries writing, yet each holds a record of change. So the sculpture stages two sorts of hiddenness side by side: one locked into language, one simply old and mineral.

The setting matters. At an intelligence agency, concealing and revealing information is the daily job. Sanborn put a public artwork on that ground and made it keep part of itself back. Employees and visitors pass a text that will not open to them. That is the point of the work rather than a defect in it.

What can be stated firmly is narrow. The maker, the date, the materials, the site, and the count of four passages with three solved are secure. What the solved passages ultimately mean for the artist or the Agency, and any proposed reading of the fourth, remain guesswork. The sculpture does not need those guesses. It works on the plain visible fact of a copper page that has only been part read, standing in stone and water at a place where reading other people’s messages is power.