🔐 Playfair Cipher Implementation (Python)

A complete and educational Python implementation of the Playfair Cipher encryption algorithm. This project demonstrates matrix generation, digraph processing, and classical substitution encryption & decryption using structured logic.

It is created as a learning and academic project to understand how classical digraph-based cryptography works internally, not as a production-ready security system.

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🧱 Project Structure

playfair-cipher-python/
│
├── assets/           # Screenshots
├── app.py            # Basic CLI Version
├── interactive.py    # Rich-powered CLI
├── requirements.txt  # Dependencies
├── LICENSE           # Project license
└── README.md         # Project documentation

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✨ Features

🔑 Key Matrix Generation

• Generates a 5×5 Playfair matrix using a keyword
• Merges J into I (standard academic convention)
• Fills remaining alphabet in correct order
• Automatically removes duplicate letters

🔒 Encryption

• Applies Playfair rules:
  • Same row → shift right
  • Same column → shift down
  • Rectangle rule → swap columns
• Produces correctly formatted ciphertext

🔓 Decryption

• Reverses Playfair encryption logic:
  • Same row → shift right
  • Same column → shift down
  • Rectangle rule → swap columns
• Outputs decrypted plaintext (including padding if present)

🧮 Educational Focus

• Clean and readable logic
• Modular and structured functions
• Ideal for beginners in cryptography
• No external dependencies

🎨 Rich CLI (Interactive Mode)

• Beautiful colored terminal UI using Rich
• Displays key matrix in a structured table
• Interactive prompts with validation
• Clean and readable output panels

⚡ Dual Mode Support

• 🧼 Basic CLI → Lightweight, no dependencies
• 🎨 Rich CLI → Enhanced UI with colors and panels

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🛠 Technologies Used

Technology	Role
Python 3	Core programming language
String Module	Alphabet handling
Matrix Logic	5×5 key table implementation
Rich	Styled CLI, colors, panels

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📌 Purpose of This Project

This project is built to:

• Understand classical Playfair cryptography
• Learn digraph substitution techniques
• Explore historical encryption algorithms
• Study matrix-based encryption systems

⚠️ This project is intended strictly for learning and demonstration purposes.

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▶️ How to Run

1️⃣ Clone the repository

git clone https://github.com/ShakalBhau0001/playfair-cipher-python.git

2️⃣ Navigate to the project folder

cd playfair-cipher-python

3️⃣ Install Dependencies

pip install rich

OR

pip install -r requirements.txt

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4️⃣ Running the Project

🧼 Basic CLI Version

python app.py

🎨 Rich Interactive Version

python interactive.py

5️⃣ Follow the prompts for Basic CLI Version

• Enter a keyword
• Choose direction:
  • E → Encrypt
  • D → Decrypt
• Enter your message
• View the result

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🔎 Example

Encryption :

Enter keyword: MONARCHY

Encrypt or Decrypt (E/D): E
Enter message: INSTRUMENTS

Encrypted: GATLMZCLRQXA

Decryption :

Enter keyword: MONARCHY

Encrypt or Decrypt (E/D): D
Enter message: GATLMZCLRQXA

Decrypted: INSTRUMENTSX

(Note: Final padding letter may appear during decryption.)

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⚠️ Limitations

• Not secure for real-world use
• Classical cipher (easily breakable)
• Does not automatically remove padding after decryption
• CLI-based interaction only

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🌟 Future Improvements

• Add automatic padding removal
• Add configurable I/J handling
• Add input validation for shift values
• Add file encryption support
• Create GUI version
• Combine into a classical cryptography toolkit

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⚠️ Disclaimer

This implementation is created for educational and learning purposes only. The Playfair Cipher is historically significant but cryptographically insecure and must not be used to protect real-world sensitive data.

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📸 Preview

1. Encryption

2. Decryption

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🪪 Author

Shakal Bhau

GitHub: ShakalBhau0001

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⭐ Support

If you like this project, consider giving it a ⭐ on GitHub!

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