Hill Cipher Web Application

A modern web application for encrypting and decrypting text using the Hill Cipher algorithm. This tool provides an intuitive interface for matrix-based cryptography operations.

Features

Encryption

• Text to number conversion using A=0, B=1, ..., Z=25 mapping
• Support for variable size key matrices (2x2 to 5x5)
• Automatic padding with 'X' for incomplete blocks
• Real-time matrix validation
• Modular arithmetic operations (mod 26)
• Visual feedback for successful encryption

Decryption

• Support for decrypting Hill Cipher encrypted text
• Automatic matrix inverse calculation
• Matrix invertibility checking
• Error handling for non-invertible matrices
• Input validation for matrix dimensions
• Clear visual feedback for results

How It Works

Encryption Process

1. Enter your plaintext (only letters A-Z are accepted)

2. Select matrix size (2-6)

3. Enter your key matrix values row by row

4. Click "Encrypt" to get your ciphertext

Decryption Process

1. Enter the ciphertext
2. Select the same matrix size used for encryption
3. Enter the same key matrix used for encryption
4. Click "Decrypt" to recover the plaintext

Installation and Setup

1. Clone the repository:

git clone https://github.com/yourusername/hill-cipher-app.git
cd hill-cipher-app

2. Run the application:

python app.py

3. Open your browser and navigate to:

http://localhost:5000

Requirements

• Python 3.x
• Flask
• NumPy

Technical Details

Matrix Operations

• The application uses NumPy for efficient matrix operations
• Modular arithmetic is implemented for all operations (mod 26)
• Matrix invertibility is checked before processing
• Determinant calculations are performed with proper modular arithmetic

Error Handling

• Invalid matrix dimensions
• Non-invertible matrices
• Invalid input characters
• Matrix parsing errors
• Server communication errors

Contributing

Feel free to submit issues and enhancement requests!