fcu

A cmd based program which greatly simplifies breaking any kind of codes or making one by yourself.
It's modular, which means you can add your own ciphers via json files.
You can also visit our reddit or support this project.

Installation

You need to have both node and npm installed.
Once that done just type npm i -g fcu into the cmd.
The -g flag is very important, without it the program won't work at all.

Usage

If installed correctly you can just type FCU into the console (at any directory) and you should see the list of available commands.

FCU list

This command will display all installed ciphers, sorted by the type.
Syntax: FCU l

Type is represented by an arrow from input type to output type. For example, Txt -> Img requires input in form of text, and will output data in form of an image (for example QR code works this way).
If types are divided by commas it means that multiple inputs are required.
If there is a ? before a type, it means it's a "background" input - it will be used in encoding, but won't be recovered in decoding.

E.D.L. (Estimated Data Loss) is also displayed next to each cipher. It indicates how much data (on average) can be lost due to using the cipher.

FCU encode/decode

The basic encoding/decoding command.
Syntax: FCU e/d <cipher> <source> <target>

It will use provided input, encode/decode it using selected cipher and then save to the output path.
If the command is used without <source> and <target> arguments it will display help for given cipher, with a list of all available flags. For text, input can be either a path to a .txt file or the text itself. Output path can also be left empty to display results directly in the console.
For image, both input and output have to be a path to the image file.

For example, command FCU encode Rot13 -r 5 "Wow!" "file.txt" would input Wow!, encode it using Rot13 (with rot set to 5) cipher and then save it to file.txt.

In case of encode command, after encoding program will automatically decode the result and compare it to the input file. This way it can detect how much data was lost due to the use of the cipher.

FCU sequence encode/decode

This command will perform few encodings/decodings at once.
Syntax: FCU s e/d <source> <target> [ciphers...]

The last argument should be a list of ciphers to be used (in proper order).
Ciphers can be used with flags, but it requires both cipher name and all it's flag to be inside ", for example "Rot13 -r 5".
This command also checks data loss, but instead of doing it for each cipher, it checks the whole sequence at once, making the results more precise.

FCU test

Runs diagnostic tests on a cipher.
Syntax: FCU t <cipher> or FCU t all

Making your own ciphers

The package contains a very detailed documentation on how to make your own ciphers.
It can also be opened using FCU doc.