Enigma Simulator

An npm module for Enigma Machines. It can simulate a Wehrmacht Enigma I and Kriegsmarine M3 and M4 variants.

Install

npm install enigma-simulator

Example Usage

Require the enigma-simulator module:

var enigma = require('enigma-simulator');

Create a Wehrmacht Enigma I Machine with a B reflector and rotors III, II, I with default positions and ring settings:

var e1 = enigma();
e1.encodeString('ABC'); // 'FUV'

Or create an Enigma machine with your own settings (rotors, positions, ringSettings, reflector, plugboardPairs):

var m3 = enigma(['IV', 'I', 'III'], [3, 5, 20], [7, 12, 14], 'C', 'AS TH LR');
m3.encodeString('ABC'); // 'IRD'

Create a Kriegsmarine M4 Enigma Machine:

var m4 = enigma(['Gamma','III','II','I'], [0,0,0,0], [0,0,0,0], 'BThin');
m4.encodeString('ABC'); // 'BPF'

Documentation

enigma()

Syntax

enigma(rotors, positions, ringSettings, reflector, plugboardPairs)

Output

Returns an instance of EnigmaMachine.

Parameters

rotors Optional. An array of strings which represent the rotor types to use in which position (left to right). Available rotors are:

Rotor	Encoding	Turnover	Notes
'I'	EKMFLGDQVZNTOWYHXUSPAIBRCJ	Q	Wehrmacht Enigma I
'II'	AJDKSIRUXBLHWTMCQGZNPYFVOE	E	Wehrmacht Enigma I
'III'	BDFHJLCPRTXVZNYEIWGAKMUSQO	V	Wehrmacht Enigma I
'IV'	ESOVPZJAYQUIRHXLNFTGKDCMWB	J	Kriegsmarine M3
'V'	VZBRGITYUPSDNHLXAWMJQOFECK	Z	Kriegsmarine M3
'VI'	JPGVOUMFYQBENHZRDKASXLICTW	Z & M	Kriegsmarine M4
'VII'	NZJHGRCXMYSWBOUFAIVLPEKQDT	Z & M	Kriegsmarine M4
'VIII'	FKQHTLXOCBJSPDZRAMEWNIUYGV	Z & M	Kriegsmarine M4
'Beta'	LEYJVCNIXWPBQMDRTAKZGFUHOS		Kriegsmarine M4, fourth rotor, didn't rotate, used with thin reflectors
'Gamma'	FSOKANUERHMBTIYCWLQPZXVGJD		Kriegsmarine M4, fourth rotor, didn't rotate, used with thin reflectors

The array expects 3 items (to simulate the Wehrmacht Enigma I or Kriegsmarine M3) or 4 items (for the Kriegsmarine M4). If the Enigma Machine is initialized with four rotors, it is assumed the left-most rotor is a Beta/Gamma rotor in an M4. Therefore the left-most rotor will not rotate.

Defaults to [III, II, I].

positions Optional. An array of integers [0..25] which represent the positions of the rotors. Defaults to [0, 0, 0].

ringSettings Optional. An array of integers [0..25] which represent the ring settings (or Ringstellung) of the rotors. Defaults to [0, 0, 0].

reflector Optional. A string which represents the reflector type used. Available reflectors are:

Reflector	Encoding	Notes
'B'	YRUHQSLDPXNGOKMIEBFZCWVJAT
'C'	FVPJIAOYEDRZXWGCTKUQSBNMHL
'BThin'	ENKQAUYWJICOPBLMDXZVFTHRGS	Kriegsmarine M4
'BThin'	RDOBJNTKVEHMLFCWZAXGYIPSUQ	Kriegsmarine M4

Defaults to 'B'.

plugboardPairs Optional. A string containing a list of pairs of letters separated by spaces. This represents the letters that should be switched on the plugboard (or Steckerbrett). Defaults to an empty string (no substitutions).

EnigmaMachine.encodeString()

Syntax

enigmaMachine.encodeString(text)

Output

Returns a string which is the encoding/decoding of text.

Parameters

text The text to encode/decode. The text is required to only contain uppercase letters from the latin alphabet.

Learn More

A good introduction to the Enigma Machine is this Numberphile video. You can find out more about the details of the inner workings of the machine on Dirk Rijmenants' website. One of the more complex quirks of the Enigma Machine's mechanism is the "double step". You can see this in action in this video.

Contributors 🎉

mrpjevans