LANGLEY, Va. -- They spent more than three decades cracking foreign codes for the ultrasecret National Security Agency. Now, Dennis McDaniels and Ken Miller may have met their match in a peaceful courtyard in suburban Virginia.
This is not just any courtyard. It joins the new and old buildings of the Central Intelligence Agency, the NSA's sister agency and long-time rival. In one corner rises "Kryptos," a 10-year-old sculpture of curving bronze and petrified wood -- and inscribed with a secret message. McDaniels, Miller and an assortment of other sleuths, including a physicist at the CIA, have been trying to decipher it off and on for eight years.
To the untrained eye, "Kryptos" is a jumble of seemingly random letters on a grillwork greening with age. But code-breakers view it as a rock climber would a towering and unexplored sheet of granite.
McDaniels and Miller were part of a four-member NSA team that almost reached the top of that cerebral cliff before they became stranded in December 1992, unable to spot a fissure that would propel them those final feet.
They were able to decipher three of the code's four parts, 768 characters. The final 97 characters remain a mystery. The decoded messages include a poetic passage referring to "subtle shading" and "the absence of light," the longitude and latitude for CIA headquarters, and the breathless account of archaeologist Howard Carter on opening King Tut's tomb in 1922.
"We always believe it will be broken," says McDaniels, a quiet and affable retired cryptanalyst, who still tinkers with the remaining section while lying on his couch at home watching television.
"You couldn't be in this business if you didn't think it was possible," adds Miller, a trim former Marine who served in a reconnaissance unit in Vietnam before spending 31 years on the less hazardous duty of code-breaking.
When the final section is decrypted there will still be work to do. The four passages in the sculpture pose a riddle whose solution is in the office of CIA Director George J. Tenet, one more secret passed down from his predecessors.
"Kryptos," Greek for "hidden," is the work of Washington sculptor James Sanborn, whose work often employs cryptograms. One of his cryptic sculptures was unveiled last month outside the Smithsonian's Hirshhorn Museum; another perplexes students and faculty at the University of Connecticut.
To complete his sculpture at the CIA's parklike headquarters, Sanborn turned to Ed Scheidt, the agency's retired chief of cryptology, known among the shadowy types as the "Wizard of Codes."
Scheidt spent several months designing a code, though not as indecipherable as those employed to protect government secrets.
"Its intent was to last roughly five years; it was modeled along those lines," says Scheidt. As the message progressed on "Kryptos," he made the passages tougher to break.
"There was a change in the methodology," he says. "It was intentional."
Without providing details, Scheidt says the riddle's answer addresses the painstaking work of gathering and analyzing intelligence. In this veiled world, what seems apparent can be a distortion and the truth is learned by peeling back the layers, much like deciphering "Kryptos," Scheidt explains.
When the sculpture was unveiled in November 1990, then-CIA Director William H. Webster praised Sanborn's work. "You have captured much of what this agency is all about," he said. "We like to be tested. And we enjoy a challenge."
And apparently the CIA likes to challenge others to mental gymnastics.
Two years after the ceremony, Adm. William O. Studeman, the CIA's deputy director and a former NSA director, asked whether the NSA's cryptanalysts had the intellectual muscle to solve the "Kryptos" mystery.
"He laid the challenge down, 'You guys are so hot, let's see how hot you are,'" recalls Miller, who refers to a small black notebook that includes key dates and developments in their quest.
The NSA's director, Vice Adm. John M. "Mike" McConnell, announced the challenge during a ceremony inside the agency, then called for the creation of a team of cryptanalysts to try to break the code.
Miller headed the four-member group. They worked on their own time, during lunch hours, before and after work. They e-mailed each other hints and gathered in the cafeteria to pore over the hidden text.
They used a personal computer to do the "grunt work" of cryptanalysis, looking for the "frequency distribution" of various letters that might help unlock the mystery. By the end of November 1992, the team broke three of the four sections. McDaniels solved part three on his living-room couch. The NSA team worked on the code for another month without making further headway.
"It's always frustrating," says Miller.
"Still is," adds McDaniels.
NSA officials contacted their CIA counterparts early in 1993 and told them that three sections had been broken. What was the CIA's response? Were CIA employees also working on it?
The codebreakers never asked. They live in a don't-ask-questions culture, solving problems and remaining in the shadows.
"It just sat dormant and we walked away from it, as we do with any of our successes," Miller says matter-of-factly.
Last year, news accounts revealed that two others had unlocked most of the "Kryptos" mystery: CIA physicist David Stein, in February 1998, and Jim Gillogly, a California computer scientist, last June. They, too, failed to uncover the fourth section.
Though the NSA team was the first to decipher the three sections of "Kryptos," CIA spokesman Tom Crispell quickly points out that Stein completed his work with paper and pencil -- and without the benefit of a computer. Crispell was uncertain whether others at the agency are also working on "Kryptos."
Stein is "the only person I'm aware of," he says. "There was never a formal undertaking to solve this riddle."
Scheidt and Sanborn receive occasional letters and e-mail asking for clues and offering solutions -- some outlandish. One man in France is convinced that "Kryptos" has a biblical connotation and sees a serpent superimposed on the letters. Another would-be cryptographer argues that the embedded message refers to the War of 1812.
"Lots of harebrained schemes," says Sanborn, who hopes that one day the entire message will be revealed.
"I'd love to have somebody do it entirely," he says. "It's going to be tough."
While Stein could not be reached for comment, Gillogly remains hopeful that he will be able to solve the final section with his Pentium II computer.
A past president of the American Cryptogram Association, Gillogly has been hooked on secret messages since he was a child. He finds this one particularly troublesome.
"It's difficult because there's no hint about what kind of cipher this is," he says.
Meanwhile, McDaniels continues to flop on his couch with a pad and paper, when he's not playing volleyball or visiting his grandchildren. Miller also continues to "scratch at it."
Old habits die hard for cryptanalysts.
"You can lay it down," Miller says, "but you can't leave it alone."