Edward Hebern, despite never working for the US government, underpinned several important components of the United States’ cryptologic success in World War II.
As early as 1915 Hebern experimented in cipher generation by wiring two electric typewriters together. This early work was the germ of the idea for Hebern’s most significant invention—the wired rotor, which was a Bakelite disk with 26 equally spaced contact studs on each face, connected by wires so that electrical current entering one side of the rotor would exit from a different position on the other. Hebern learned to wire his rotors to produce as flat of a polyalphabetic frequency distribution as possible.
Both the US Army and US Navy tested Hebern’s invention for use in military cryptography and studied his new machines. Together, the services developed the joint Army/Navy Converter M-134-C (SIGABA) / MARK II ECM, arguably WWII’s most secure cryptographic device.
The Army Security Agency said, “Hebern invented the type of rotor which is used in many rapid, electrical, rotor cryptographs of the Army and Navy…. Hebern’s machine first brought the physical embodiment of this principle to the attention of the Army and Navy in a form so practical that it has never been abandoned.” Navy Captain Laurance Safford summed up Hebern’s contribution this way: “Hebern has never received adequate recompense for his part in the development of the [ECM]. He is the original inventor.”
Hebern was the first inventor in the United States to patent the wired rotor, which both the army and navy acknowledged as essential to the development of SIGABA, arguably the most secure cipher machine of World War II.