Security Package

he project is a library offering secure encryption and decryption algorithms utilizing four classical methods: Caesar cipher, Vigenère cipher, Substitution cipher, and Playfair cipher. It adheres to clean code principles and employs object-oriented programming (OOP) best practices.

The core of the project is an abstract Cipher class serving as the foundation for all ciphers, alongside a main class demonstrating their use. The Cipher abstract class encompasses common methods like key management, encryption, decryption, and key validation. Each of the four ciphers extends this class, implementing its own encryption and decryption logic. Users can customize inputs such as keys and messages.

The Caesar cipher substitutes each plaintext letter with another letter a fixed number of positions down the alphabet. The Vigenère cipher, a more intricate polyalphabetic cipher, uses multiple Caesar ciphers with shifting based on a keyword. The Substitution cipher replaces each letter with another according to a predefined table. The Playfair cipher encrypts letter pairs using a 5x5 grid and digraphs.

The main class offers a straightforward command-line interface for user interaction, enabling message and key input, cipher selection, and encryption or decryption. It also includes test cases to ensure the accuracy of the encryption and decryption processes.