Secrecy at CIA headquarters extends all the way to the courtyard. Kryptos, a granite-and-copper sculpture by Washington artist Jim Sanborn, was quietly installed last November near a new building on the agency's grounds. Taxpayers financed the $250,000 work, but that does not guarantee public access. Sanborn's sculpture features a 2,000-character encoded message that is believed to have been penned by a well-known writer whose name has not been disclosed. Besides the artist and the author, only CIA director William Webster knows what the top-secret phrase says, according to an agency spokesman. The CIA does not allow the general public to visit its Langley, Va., compound, so Kryptos is on view only for employees or authorized visitors. Ironically, the Sanborn sculpture constitutes what the CIA calls its "Tribute to Information."