Data Encryption Standard (DES) Implementation

Project Overview

This project implements the Data Encryption Standard (DES) algorithm from scratch in C# using Visual Studio. It provides functionality to encrypt and decrypt text-based PDF files. A GUI application allows users to input a file, encrypt it, and then decrypt it using the DES algorithm, following the OOP paradigm.

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Features

1. Encrypt and Decrypt PDF Files

   • Accepts a text-based PDF file as input for encryption or decryption.
   • Generates encrypted or decrypted PDF files as output.

2. Custom DES Implementation

   • DES Key Scheduling with 16 rounds of keys.
   • The first 8 characters of full name(MAHNOORI) are used as the 64-bit master key.

3. Neat GUI Application

   • Simple interface to select files, execute encryption/decryption, and save outputs.

4. No External Libraries for DES

   • The DES algorithm, including key scheduling and bit-level operations, is implemented from scratch.

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How to Use

1. Prerequisites

• Install Visual Studio (2022 or later).
• Install .NET Framework or .NET Core SDK compatible with your project.

2. Build and Run

• Clone or download the project files.
• Open the solution (DES_Encryption.sln) in Visual Studio.
• Build the project (Ctrl+Shift+B) to generate the executable file.
• Run the application (F5).

3. Steps to Encrypt/Decrypt

1. Launch the application.
2. Select the input PDF file containing text.
3. Choose to either encrypt or decrypt the file.
4. Save the resulting encrypted or decrypted PDF.

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Technical Details

• Key Scheduling:
  Generates 16 round keys from the 64-bit master key derived from the first 8 characters of the user’s full name.

• Encryption/Decryption Process:

  • Split the data into 64-bit blocks.
  • Perform an initial permutation (IP).
  • Apply 16 rounds of Feistel cipher using the generated round keys.
  • Execute a final permutation (IP-1).

• File Handling:
  Reads the text from the input PDF, processes it using DES, and writes the output to a new PDF.