Vigenère Cipher in Python

This project implements a Vigenère cipher in Python. The script can both encrypt and decrypt text using a provided key.

Features

• Encryption and Decryption:
  Uses a Vigenère cipher algorithm to shift characters based on a repeating key.

• Flexible Input:

  • Converts all letters to lowercase before processing.
  • Leaves non-alphabet characters (such as spaces, numbers, or punctuation) unchanged.

• Reusable Functions:
  Contains helper functions encrypt() and decrypt() that wrap the main vigenere() function.

How It Works

1. Vigenère Function:
   For each letter in the input message, the function:

   • Finds the corresponding letter in the key (cycling through the key with modulo arithmetic).
   • Determines the shift (offset) using the position of the key letter in the alphabet.
   • Applies the shift (addition for encryption, subtraction for decryption) to the message character.

2. Encryption vs. Decryption:
   The function takes an optional parameter direction:

   • A value of 1 encrypts the text.
   • A value of -1 decrypts the text.

Usage

1. Clone the Repository:

   git clone https://github.com/yourusername/your-repo-name.git
   

2. Navigate to the Project Directory:

   cd vigenere_Python_Cypher
   

3.Run the Script:

python vigenere.py

*(Make sure you have Python 3 installed on your system.)*

Contributing

Contributions are welcome! Feel free to fork this repository, improve the code, or add new features. When submitting pull requests, please include a brief description of your changes.

License

This project is open source and available under the [MIT License]

Credits

• g3tech
• freecodecamp