Cryptology and the origins of spread spectrum: Engineers during World War II developed an unbreakable scrambler to guarantee secure communications between Allied leaders; actress Hedy Lamarr played a role in the technology

Deep in the guarded labyrinth of the newly constructed Pentagon, an army lieutenant with top security clearance inserts a voltohmmeter probe into a horse-shoe-shaped, 7-foot-high panel of electronic equipment. The apparatus is top secret; the room where it sits, with its polished tile floor, is windowless.