Advanced Encryption Standard (AES) Implementation

A robust, pure-Python implementation of the Advanced Encryption Standard (AES). This project provides a transparent look into the inner workings of symmetric-key cryptography, supporting multiple key lengths and operating modes.

🚀 Features

• Variable Key Lengths: Full support for AES-128, AES-192, and AES-256.
• Operating Modes:
  • ECB (Electronic Codebook): Standard block-by-block encryption.
  • CBC (Cipher Block Chaining): Enhanced security using an Initialization Vector (IV) to prevent pattern recognition.
• Zero Dependencies: Built using standard Python libraries—no external installations required.
• Educational Design: Clean code structure following the official FIPS 197 specification.

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🛠 How It Works

The implementation handles the four main stages of the AES round transformation:

1. SubBytes: A non-linear substitution step using a lookup table (S-box).
2. ShiftRows: A transposition step where rows of the state are shifted cyclically.
3. MixColumns: A mixing operation that operates on the columns of the state.
4. AddRoundKey: The state is combined with a round key using bitwise XOR.

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💻 Getting Started

Prerequisites

• Python 3.6 or higher.

Installation

Clone the repository to your local machine:

git clone [https://github.com/4rn4vk/Advanced-Encryption-Standard-AES-.git](https://github.com/4rn4vk/Advanced-Encryption-Standard-AES-.git)

cd Advanced-Encryption-Standard-AES-

🚀 How to Use

Follow these steps to encrypt or decrypt your data using the script:

1. Locate the "Code Compiler" Section: Open AES_Final.py and scroll to the bottom of the file.

2. Configure Your Inputs:

   • Find the Encryption or Decryption print statements.
   • Input your Plain text (for encryption) or Cipher text (for decryption) as a string.
   • Input your Key as a string (ensure it is 16, 24, or 32 bytes long).

3. Toggle CBC Mode: * Do not modify the arguments inside the print statements.

   • Instead, change the boolean flags directly under the Code Compiler heading:

   # Set to True for CBC mode, False for ECB mode
   CBC_encryption = True
   CBC_decryption = True

4. Run the Script: Execute the file in your terminal:

   python AES_Final.py

5. View Results: The encrypted or decrypted value will be printed directly to your console.

Note: The script automatically handles the key expansion and round calculations based on the key string length you provide.