Cryptanalysis of the Enigma Bletchley Park to describe the network that used the same Enigma setting sheets. Initially these were recorded using coloured pencils and were given the names "red", "light blue" etc., and later the names of birds such as "kestrel". During World War II the settings for most networks lasted for 24 hours, although towards the end of the war, some were changed more frequently. The sheets had columns specifying, for each day of the month, the rotors to be used and their positions, the ring positions and the plugboard connections. For security, the dates were in reverse chronological order down the
Enigma machine Enigma variant was a four-wheel unsteckered machine with multiple notches on the rotors. This model was equipped with a counter which incremented upon each key press, and so is also known as the "counter machine" or the "Zählwerk" Enigma. Enigma machine G was modified to the "Enigma I" by June 1930. Enigma I is also known as the "Wehrmacht", or "Services" Enigma, and was used extensively by German military services and other government organisations (such as the railways) before and during World War II. The major difference between "Enigma I" (German Army version from 1930), and commercial Enigma models was