Enigma simulators

Introduction

As soon as I got interested in cryptology, I wanted to write computer programs to make the encryption algorithms that I was discovering a reality. One of the first programs I wrote simulated the Enigma.

There are many models of the Enigma. The Crypto Museum website describes them all. In addition, for each of these models there are often different sets of rotors.

Panorama of my simulators

The Enigma Model D

This is the most popular commercial Enigma model. This model was used by the Austrian army as well as by the Italian and Spanish (Franco's) army. It was also used by the Germans to protect the communications of railways (Railways Enigma). In these cases, the rotor wiring has been changed.

The Enigma I / Enigma M3

The Enigma I is the machine used by the German Army and Air Force. The main difference with the commercial version is the addition on the front panel of a plugboard which greatly improves security. This machine uses 5 rotors (I,II,III,IV,V). The navy was using the M3 model. There is no fundamental difference between these two models. They are compatible. The M3 model has on the other hand three additional rotors (VI,VII,VIII).

The Enigma M4

This is an evolution of the previous model and is moreover compatible with it (the reverse is not true). Safety is enhanced by the addition of a fourth rotor. On the other hand, to be able to use the M3 and transform them into M4, the reflector of the M3 (UKW B) is replaced by two elements: a new reflector but thinner and a rotor but also thinner than the others rotors and which therefore must be put on the side of the new reflector.

The Enigma Model G

This Enigma, used by the Abwehr, is special in several ways. It works much like the commercial Enigma (it has no Steckers) but the rotors turn more frequently than in the latter. On the other hand it uses specific rotors, not usable in other models.