Editing Rotor machine (section)

===Invention===
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The concept of a rotor machine occurred to a number of inventors independently at a similar time.

In 2003, it emerged that the first inventors were two [[Royal Netherlands Navy|Dutch naval officers]], Theo A. van Hengel (1875–1939) and R. P. C. Spengler (1875–1955) in 1915 (De Leeuw, 2003). Previously, the invention had been ascribed to four inventors working independently and at much the same time: [[Edward Hebern]], [[Arvid Damm]], [[Hugo Koch]] and [[Arthur Scherbius]].

In the [[United States]] [[Edward Hugh Hebern]] built a rotor machine using a single rotor in 1917. He became convinced he would get rich selling such a system to the military, the [[Hebern Rotor Machine]], and produced a series of different machines with one to five rotors. His success was limited, however, and he went [[bankrupt]] in the 1920s. He sold a small number of machines to the [[US Navy]] in 1931.

In Hebern's machines the rotors could be opened up and the wiring changed in a few minutes, so a single mass-produced system could be sold to a number of users who would then produce their own rotor keying. Decryption consisted of taking out the rotor(s) and turning them around to reverse the circuitry. Unknown to Hebern, [[William F. Friedman]] of the [[United States Army|US Army]]'s [[Signals Intelligence Service|SIS]] promptly demonstrated a flaw in the system that allowed the ciphers from it, and from any machine with similar design features, to be cracked with enough work.

Another early rotor machine inventor was Dutchman [[Hugo Koch]], who filed a [[patent]] on a rotor machine in 1919. At about the same time in [[Sweden]], [[Arvid Gerhard Damm]] invented and patented another rotor design. However, the rotor machine was ultimately made famous by [[Arthur Scherbius]], who filed a rotor machine patent in 1918. Scherbius later went on to design and market the [[Enigma machine]].