What does it say about the Central Intelligence Agency that its agents can crack the secret codes of enemy nations but can't unravel a coded sculpture sitting outside their cafeteria window?

It says, perhaps, that artist Jim Sanborn, who created the cryptographic sculpture named Kryptos that sits on CIA grounds, could have a career in covert operations if he ever grows tired of stumping the experts.

It's been nearly 15 years since Sanborn installed the 12-foot-high, verdigrised copper, granite and wood sculpture inscribed with four encrypted messages at the CIA's Langley, Virginia, headquarters in 1990. And it's been seven years since anyone made progress at cracking its code.

Can you solve the puzzle?