enigmacrack

enigmacrack

Cryptanalysis tools to break Enigma ciphers

Table of Contents

• Usage
• Options
  • Enigma Settings
  • Cryptanalysis Settings
• Methods
  • Index of Coincidence
  • N-Grams
• Targets

Usage

enigmacrack method target [options] ciphertext

Options

Enigma Settings

Flag	Description
-w rotors	Set the rotor configuration (e.g. 'I II III').
-p positions	Set the initial rotor positions (e.g. 'ABC').
-u reflector	Set the reflector (e.g. 'B').
-s plugboard	Set the plugboard pairs (e.g. 'ABCDEF').

Cryptanalysis Settings

Flag	Description
-c plaintext	Set the known plaintext.
-C position	Set the position of known plaintext.
-d path	Load dictionary words from the given file. Dictionary must contain one word per line, be sorted alphabetically, and be all uppercase.
-l language	Set the language ('english' or 'german', for IOC method).
-m float	(REQUIRED) Set the minimum score threshold.
-M float	(REQUIRED) Set the maximum score threshold.
-n file	Load n-grams from the given file.
-x	Assume X-separated words in plaintext.

Methods

ioc

This method uses Index of Coincidence for cryptanalysis. The Index of Coincidence measures how likely it is to draw two random letters from a given text. As correct settings are discovered, intermediary plaintexts should approach the established Index of Coincidence value for its language.

Utilizing this method, it is possible to decrypt ciphertext with no known settings in a short amount of time, given we know the language the source text was written in. This requires some user intervention, however.

ngram

Use n-grams for cryptanalysis. n-grams may be generated from a corpus using the genngrams script.

Targets

Target	Description
rotor[1-3]	Crack the rotor (Walzen) configuration. Index indicates which rotor to crack.
rotors	Crack all rotor configurations.
position[1-3]	Crack an initial rotor position.
positions	Crack all initial rotor positions.
reflector	Crack the reflector (Umkehrwalze).
plugboard	Crack a plugboard (Steckerbrett) setting.