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CrypTool by Ali Burhan | https://github.com/ab-ratul/
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An Interactive Cryptographic Engine & Vulnerability Scanner

Built by Ali Burhan | https://github.com/ab-ratul/cryptool

CrypTool is a Python-based command-line interface (CLI) application designed to demonstrate the fundamental mechanics of data confidentiality. Developed as part of the DecodeLabs Industrial Training Kit (Project 2: Basic Encryption & Decryption), this tool transforms static text into secure ciphertext using mathematical obfuscation and actively audits its own security through automated brute-force scanning.

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📑 Table of Contents

1. Features
2. Cryptographic Architecture
3. For Recruiters: Technical Highlights
4. Getting Started (Beginner Guide)
5. Usage & Shortcuts

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✨ Features

• Caesar Cipher Engine: Implements mono-alphabetic substitution using a user-defined integer shift key.
• Vigenère Cipher Evolution: Upgrades static defense to polyalphabetic substitution using a dynamic string keyword, mitigating standard frequency analysis attacks.
• Automated Vulnerability Scanner: Simulates a penetration testing environment by brute-forcing ciphertext (Caesar) to expose the "single point of failure" in basic ciphers.
• Dynamic Network I/O: Fetches a 10,000-word English dictionary directly from GitHub at runtime to perform intelligent plaintext identification.
• Audit Logging: Automatically records successful dictionary-attack breaches (timestamp, shift key, and payload) to a local compromised_data.txt file.
• Resilient CLI: Features global keyboard shortcuts, strict input validation, and network timeout fallbacks to ensure an error-free user experience.

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🧮 Cryptographic Architecture

This tool operates on the Input-Process-Output (IPO) model, converting standard raw ASCII text into integers before applying modular arithmetic.

The core mathematical transformation for the Caesar Cipher relies on a symmetric key $n$ and character position $x$:

• Encryption: $E_n(x) = (x + n) \pmod{26}$
• Decryption: $D_n(x) = (x - n) \pmod{26}$

By preserving non-alphabetic characters (spaces, punctuation) and seamlessly wrapping the alphabet using the modulo operator (% 26), the engine prevents mathematical overflow and maintains data integrity during the encryption lifecycle.

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🎯 Technical Highlights

If you are reviewing this code, here is what this project demonstrates:

• Object-Oriented Programming (OOP): The core logic is encapsulated within a CryptographicEngine class, making the code modular, reusable, and easy to integrate into larger security frameworks.
• Offensive Security Tooling: The vulnerability scanner mimics real-world password cracking tools (like Hashcat). It sanitizes raw data, splits strings, and scores potential plaintexts against a loaded dictionary to automate the identification of compromised data.
• Exception Handling & Fault Tolerance: The script is fortified with try-except blocks. If the external dictionary URL goes offline, the tool silently falls back to a hardcoded micro-dictionary without crashing. Invalid user inputs are caught and handled gracefully.
• Custom Interrupt Signals: Implements a custom exception (ReturnToMenu) bound to Ctrl+B, showcasing advanced control flow manipulation within Python's standard while loops.

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🚀 Getting Started

Prerequisites

You only need Python 3.x installed on your system. No external pip libraries are required; the script relies entirely on standard built-in Python libraries (os, time, urllib, datetime, sys).

Installation

1. Clone the repository to your local machine:

   git clone https://github.com/ab-ratul/cryptool.git

2. Navigate into the project directory:

cd cryptool

3. Run the application:

python cryptool.py

💻 Usage & Shortcuts

Upon launching, you will be greeted by the CrypTool interactive terminal. Enter a number between 1 and 6 to select your desired cryptographic module.

Global Keyboard Shortcuts

To make navigation fast and professional, the following shortcuts are hardcoded into the input listener:

Ctrl + C: Instantly safely terminate the application from anywhere.

Ctrl + B + Enter: Abort the current operation and immediately return to the main menu banner.

Example Workflow: Testing the Scanner

Select Option 1 and encrypt the phrase:

Security architecture is critical with a shift of 5

Copy the resulting ciphertext.

Select Option 5 and paste the ciphertext. Press enter!

Watch as the tool brute-forces 25 keys, identifies the english words, isolates the correct payload, and writes the compromise to your local log file. The log file is saved in the same folder as compromised_data.txt