Enigma Machine

Description

Introduction

The enigma was an encryption machine used in and post WWII. It used physical rotors to encode and decode message. My implementation is for the "Glühlampenmaschine" and later models; Complete with plugboard, rotors, and reflector. The enigma machine was deemed unbreakable at the time due it it's complexity but it's cipher is not secure by today's standards.

My Implementation

I have implemented the enigma machine as a command line tool using rust and standard library (std::env). My main goal was to create a command line interface to gain experience parsing arguments and flags to configure the encoding of the message. There are no other dependencies.

Soruces

• Wikipedia 1 - Enigma Page
• Wikipedia 2 - Rotors and Internals

Using

Example

This example will decode "JDPEN XCJJO" into Hello World. This can be found in the help page.

./enigma --rotor "EKMFLGDQVZNTOWYHXUSPAIBRCJ" V A --rotor "AJDKSIRUXBLHWTMCQGZNPYFVOE" E A --rotor "BDFHJLCPRTXVZNYEIWGAKMUSQO" Q A --reflector "YR UH QS LD PX NG OK MI EB FZ CW VJ AT" --message "JDPEN XCJJO"
OUTPUT: "HELLO WORLD"

Flags

--rotor | -r

Use --rotor ENCODING TURNOVER POSITION to add and configure a rotor.

ENCODING is the encoding of the rotor. This is a string of 26 characters. Each character is a letter in the alphabet. A letter can only be used once but can be used in any order.

TURNOVER is the letter that will cause the next rotor to turn. This is a single character.

POSITION is the starting position of the rotor. This is a single character.

You can have as many rotors as you want.

Example:

./enigma ... --rotor "EKMFLGDQVZNTOWYHXUSPAIBRCJ" D A --rotor "AJDKSIRUXBLHWTMCQGZNPYFVOE" F B --rotor "BDFHJLCPRTXVZNYEIWGAKMUSQO" E C``

--reflector | -rf

Use --reflector "PAIRS" to configure the reflector.

PAIRS represents the pairs of letters that are connected in the reflector (required for symmetrical encryption). Each pair are two letters separated by a space. Each letter can only be used once but can be used in any order.

The reflector must be included

Example:

./enigma ... --reflector "AB CD EF GH IJ KL MN OP QR ST UV WX YZ"

--message | -m

Use --message "MESSAGE" to set the message to be encoded.

MESSAGE is the message to be encoded. This is a string of characters. Any non-alphabetic characters will be ignored and passed through.

The message must be included

Example:

./enigma ... --message "HELLO WORLD"

--plugboard | -pb

Use --plugboard "PAIRS" to configure the plugboard.

PAIRS represents the pairs of letters that are connected in the plugboard. Each pair are two letters separated by a space. Each letter can only be used once but can be used in any order. You can have as many pairs as you want.

The plugboard is optional

Example:

./enigma ... --plugboard "AB CD EF GH IJ KL MN OP QR ST UV WX YZ"

--help | -h

Use --help to print the help page.

All other arguments will be ignored

Example:

./enigma --help

--state | -s

Use --state to print the finial state of the enigma machine after encoding the message.

This is optional

Example:

./enigma ... --state

Errors

I tried to make the error messages informative. I will not show them all here but this is an example:

$ ./enigma wooooop -rotor abcdefghijklmnopqrstuvwxyz a y -rotor abc a a
["$", "wooooop", "-rotor", "abcdefghijklmnopqrstuvwxyz", "a", "y", "-rotor", "abc", "a", "a"]
Error parsing rotor 2.
Encoding must be 26 characters long.

Building

Installation

Clone the repo, build and run. (Cargo required)

$ git clone https://GitHub.com/Andrew-McCall/enigma-rs.git
$ cd enigma-rs
$ cargo build

Cargo Build

Use cargo build --release to build the binary.

$ ./enigma [flags]

The binary will be located in target/release/enigma.

Cargo Run

Use cargo run --release -- [flags] to build and run the binary with one command.

License

MIT License Copyright (c) 2023 Andrew McCall