page_title: Polish Enigma double
section_title: First double
hierarchical_section_title: Polish Enigma double / First double
caption_attribution_description: Polish copy of Enigma made by Biuro Szyfrow
context_page_description: A Polish Enigma "double" was a machine produced by the Polish Cipher Bureau that replicated the German Enigma rotor cipher machine. The Enigma double was one result of Marian Rejewski's remarkable achievement of determining the wiring of the Enigma's rotors and reflectors.
context_section_description: The Polish Cipher Bureau recognized that the Germans were using a new cipher. The Germans had mistakenly shipped a cipher machine to Poland; their attempts to recover a shipment raised the suspicions of Polish customs, and the Polish Cipher Bureau learned that the Germans were using an Enigma machine.  The Bureau purchased a commercial Enigma machine, and it attempted but failed to break the cipher.
  In December 1932, the Polish Cipher Bureau tasked Marian Rejewski with breaking the Enigma cipher machine.  A French spy had obtained some material about the Enigma, and the French had provided the material to the Polish Cipher Bureau.  By that time, the commercial Enigma had been extended to use a plugboard.  Rejewski made rapid progress and was able to determine the wiring of the military Enigma.  The Bureau modified its commercial Enigma rotors, reflector, and internal wiring to match the military Enigma.  The commercial Enigma did not have a plugboard, but the plugboard could be simulated by relabeling the keys and the lamps.  The result was the first Enigma double.
caption: Prewar Polish Enigma double
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