hellfelix / cipher

An attempt at making a cipher, just to try it out

Enigma

Introduction

For this project, the aim was to create an Enigma-like cipher that lacked the weeknesses of the original Enigma machine

The basic idea is the same, although I have modified it in a few ways in order to hopefully make the cipher stronger.

This is my take on the Enigma machine.

The fatal flaw of Enigma

Upon insistance that a letter would not be encoded as itself, the "Reflektor" was added. This "rotor" would have each character "reflect" (be arbetraraly encoded) upon having gone through all three rotors before once again going through the rotor.

This made sure that no letter could come out the other side having been encoded as itself. Of course, this made no sense and added no additional security, quite the opposite. In fact, it made it much easier to recognize patterns within an encoded message.

Improvements upon the Enigma Machine

In order to improve upon the Enigma machine, I have made some changes to the original concept

1. No Reflektor

First and most obvious is the removal of the "Reflektor". Instead, I have modified the encoding to include five rotors as opposed to the traditional three, althought each rotor only encodes the letter once, meaning that each character is still encoded five times not including the plugboard. The difference of course being that the character can (in some unlikely cases) come out the other side as itself. Because this cipher lacks the Reflektor, one cannot simply decode the message by running it through the machine again the way that Enigma used to. Instead, the decoding is a separate process in which the program encodes backwards, quite litteraly. When decoding, the program reverses the positioning of the rotor and runs the message through, always yielding the original message because the pairings remain the same forewards and backwards. Note: This not being a physical machine, I could technically have added as many rotors as I wanted. I decided to stick with five because I couldn't be bothered making more imputs for the rotor positions and notches. Also, inputting starting positions and notch positions for like 50 rotors would be a nightmare.

2. Inclusion of more characters

The original Enigma machine included only the 26 letters of the alphabet (not even including space-bar). Not only did this make the messages difficult to read after deciphering (because the message would be a long string of words with no spaces between them), it also drastically dragged down the number of possible encryptions possible. For this project, I have included all of the characters supported by the firefox console i.e. ASCII table values 32 through 126. This allowes messages to include spaces between each word and punctuation while contributing to the overall "randomness" of the encrypted message. The plugboard has also been modified to reflect the added characters.

3. Rotation of the rotors

The original Enigma machine would turn its rotors only once that previous rotor had made one full revolution. This was because each rotor would have a notch, and only once that notch was in the correct position, could the next rotor turn. Once again, I have the benefit of not working with a physical machine. In the settings menu, one can input between 1 and 95 notch position for each rotor that would yield a rotation of the next rotor. This issue was somewhat of my own making though, because increasing the number of possible characters also means that a full rotation of each rotor takes much longer. Thus, the rotors will spin less often. Adding this extra level of security has the added benefit of the rotors not always spinning the same amount given a message of some length.

Usage

This section will cover how to use the cipher

Settings

Clicking the "Settings" button will bring the client to the settings Screee. Here, you can change the settings of the cipher.

Rotors

Each rotor has two possible modifications:

1. Initial position
   This is where the client can input the initial position of the rotor. For instance, an initial position of 15 would have the rotor turn 15 times before encoding the input.
   With no input, the rotors will default to 1.
2. Notch positions
   This is where the client can specify the notch positions in which rotors will turn. More details can be found in the section about the rotation of the rotors.
   With no input, the notch positions will all default to 1.

Plugboard

The plugboard works pretty much identically to the original Enigma machine. Upon typing a character into the input for another character, the plugboard will "link the two up" in both ends of the encoding/decoding process. Upon linking two characters, the two will turn light green to indicate that they are linked.
The plugboard can be reset by clicking the "Reset" button.
For every character, if no input is specified, it will be linked to itself.
Note that inputting the same character for two other characters might break the cipher. This can be fixed by resetting the plugboard.

Input/Output

On the main screen, there are two sets of input and output areas. The first one encodes and the second decodes. As long as the settings stay the same, the decoding should yield the original message. More on how this works can be found in the section about No Reflektor.