CIA Experts Still Spooked by Kryptos Puzzle

The Kryptos puzzle at CIA headquarters in Langley, Va.; it's been six years since the last breakthrough. Copyright James Sanborn. Used with permission. hide caption
The Kryptos puzzle at CIA headquarters in Langley, Va.; it's been six years since the last breakthrough.
Copyright James Sanborn. Used with permission.The Fourth Passage
The significance of the initial question-mark character -- as a beginning or a spacer -- is hotly debated by Kryptos sleuths.
?OBKRUOXOGHULBSOLIFBBWFL
RVQQPRNGKSSOTWTQSJQSSEK
ZZWATJKLUDIAWINFBNYPVTTM
ZFPKWGDKZXTJCDIGKUHUAUEK
CAR
Note:There are no breaks in the sequence.
For 15 years, a bronze sculpture in the CIA's courtyard has taunted amateur and professional code-breakers alike. Kryptos is a copper wall that features four long coded passages. Cryptographers from the National Security Administration and the CIA have cracked the first three.
But it's been six years since anyone reported progress, and sculptor Jim Sanborn claims to be the only man alive who knows the solution. Meanwhile, thriller writer Dan Brown is stoking interest: The dust jacket for his The Da Vinci Code featured clues hinting at Kryptos's significance, and Brown has suggested his next novel may somehow feature it.
Around the world, fans of puzzles and codes are racing to solve Kryptos. A Yahoo discussion group devoted to the puzzle, now boasting 500 members, is growing.