Remembering History: The artist who created Kryptos, an enigmatic puzzle-in-a-sculpture in a courtyard at C.I.A. headquarters in Langley, Va., has decided that it is time for a new hint.

The artist who created Kryptos, an enigmatic puzzle-in-a-sculpture in a courtyard at C.I.A. headquarters in Langley, Va., has decided that it is time for a new hint.

The artist who created Kryptos, an enigmatic puzzle-in-a-sculpture in a courtyard at C.I.A. headquarters in Langley, Va., has decided that it is time for a new hint.