Solving the Enigma: History of Cryptanalytic Bombe

Chapter 1. About the Enigma

As the German military grew in the late 1920s, it began looking for a better way to secure its communications. It found the answer in a new cryptographic machine called "Enigma." The Germans believed the encryption generated by the machine to be unbreakable. With a theoretical number of ciphering possibilities of 3 × 10¹¹⁴, their belief was not unjustified.^[1] However, they never reached that theoretical level of security. Nor did they count on the cryptanalytic abilities of their adversaries.

The Enigma machine based its cipher capabilities on a series of wired rotor wheels and a plugboard. Through a web of internal wiring, each of the 26 input contacts on the rotor were connected to a different output contact. The ...