Mealy String Obfuscator

This project contains code and a test program used to create a Mealy automata giving as input a string. The aim of the project is to provide a simple method to generate this kind of automata and to use it in order to obfuscate sensitive strings.

Download

• Source code
• Download binary

Usage

The MealyAutomata.fs file is the class in charge for the creation of the Mealy automata. The project MealyDeObfuscator is a simple C application that use the output generated in order to deobfuscate a given string.

Once downloaded the binary you can use the program by invoking:

StringObfuscator.exe supersecretpassword

The result of this operation will be:

      -=[ Mealy String Obfuscator ]=-
Copyright (c) 2017 Antonio Parata - [@s4tan][3]

Input text: supersecretpassword
Input: 1,0,0,0,0,1,1,0,0,0,0,0,1,0,0,0,0,1,0, Int: 135265
Output: {{'e', 's'}, {'u', 'e'}, {'p', 'u'}, {'e', 'a'}, {'r', 'r'}, {'c', 'p'}, {'t', 's'}, {'s', 't'}, {'s', 'e'}, {'w', 's'}, {'o', 's'}, {'d', 't'}, {'p', 'u'}}
Automata: {{6, 1}, {2, 5}, {3, 9}, {4, 7}, {0, 11}, {4, 7}, {2, 9}, {8, 9}, {9, 8}, {10, 7}, {4, 5}, {12, 1}, {12, 12}}

Now you can use the above output to deobfuscate the string. Below a simple C program that do this:

#include "stdafx.h"

void deobfuscate(char* text, int length, int key, char automata[][2], char output[][2])
{
	int v = 0, state = 0, i = 0;
	for (i = 0; i < length; i++)
	{
		v = key & 1;
		key >>= 1;
		text[i] = output[state][v];
		state = automata[state][v];
	}
	text[i] = '\0';
}


int main()
{
	char text[20];
	int key = 135265;

	char automata[][2] =
	{{6, 1}, {2, 5}, {3, 9}, {4, 7}, {0, 11}, {4, 7}, 
	{2, 9}, {8, 9}, {9, 8}, {10, 7}, {4, 5}, {12, 1}, 
	{12, 12}};

	char output[][2] =
	{{'e', 's'}, {'u', 'e'}, {'p', 'u'}, {'e', 'a'}, 
	{'r', 'r'}, {'c', 'p'}, {'t', 's'}, {'s', 't'}, 
	{'s', 'e'}, {'w', 's'}, {'o', 's'}, {'d', 't'}, 
	{'p', 'u'}};

	deobfuscate(text, sizeof(text)-1, key, automata, output);

	printf("Output: %s", text);
	return 0;
}

Compile

In order to compile the source code you should have installed Visual Studio >= 14 (2015 version). Once downloaded the source code just run the build.bat script file. You will find the compiled binaries in the build folder.

Test library

Once that you have compiled the code you should check that everything is ok. The MealyObfuscatorTest just try to obfuscate and deobfuscate 1000 strings. Run it to be sure that the generated automata is correct.

License information

Copyright (C) 2014-2017 Antonio Parata