Modified TypeX machine

The British TypeX Enigma machine was based on the commercial German Enigma. By January 1943 Bletchley Park had 78 TypeX machines. Bletchley Park used a Mk II version fitted with special drums, for decoding German Enigma messages as well as for encyphering Ultra output before it went overseas. The machine's greater complexity and Britain's better cypher discipline ensured that TypeX was never broken by the Germans.