Enigma rotor details

This article contains technical details about the rotors of the Enigma machine.

Understanding the way the machine encrypts requires taking into account the current position of each rotor, the ring setting and its internal wiring.

Physical design of rotors

Normalized Enigma sequences

In the following examples you can observe a normal step sequence and a double step sequence. The used rotors are (from left to right) I, II, III, with turnovers on Q, E and V. It is the right rotor's behavior we observe here (turnover V).

:"Normal sequence:"

* AAU — normal step of right rotor
* AAV — right rotor (III) goes in V—notch position
* ABW — right rotor takes middle rotor one step further
* ABX — normal step of right rotor

:"Double step sequence:"
* ADU — normal step of right rotor
* ADV — right rotor (III) goes in V—notch position
* AEW — right rotor steps, takes middle rotor (II) one step furter, which is now in its own E—notch position
* BFX — normal step of right rotor, double step of middle rotor
* BFY — normal step of right rotor

See also

Several unknown models of the Enigma machine have been discovered [...]
* http://home.comcast.net/~dhhamer/downloads/enigvar2.pdf

References

General references to Enigma rotors
* http://www.ellsbury.com/enigmabombe.htm
* http://www.ellsbury.com/ultraenigmawirings.htm
* http://www.ugr.es/~aquiran/cripto/museo/rotor.htm

References for commercial rotor wiring
* http://frode.home.cern.ch/frode/crypto/BPAbwehr/Abwehr_theft.html
* http://frode.home.cern.ch/frode/crypto/BPAbwehr/g-312.zip (Cryptologia January 2000)
* http://www.cripto.es/museo/rotor.htm

General category
* Rotor machine