How Polish Mathematicians Broke the Enigma Cipher

The paper gives a personal view of work in the Polish Cipher Bureau from 1932 to 1939 as mathematicians worked to decipher the codes of the military version of the Enigma. The author, who was a participant, relates details of the device and the successes and frustrations involved in the work. He also describes mathematical principles that enabled him and his colleagues to break successive versions of the Enigma code and to construct technical devices (cyclometers and "bombs") that facilitated decipherment of Enigma-coded messages.