Hans-Thilo_Schmidt

Hans-Thilo Schmidt (13 May 1888 – 19 September 1943) codenamed Asché or Source D, was a spy who sold secrets about the German Enigma machine to the French during World War II. The materials he provided facilitated Polish mathematician Marian Rejewski's reconstruction of the wiring in the Enigma's rotors and reflector; thereafter the Poles were able to read a large proportion of Enigma-enciphered traffic.