Vigenère Cipher Calculator

Calculates both the encryption and decryption of plain text using the Vigenère cipher, a polyalphabetic substitution method. Users input the message they wish to secure or recover, along with a keyword that dictates the shift pattern for each letter. The tool systematically applies this key across the entire message to produce the corresponding ciphertext or plaintext. This process demonstrates how repeating keywords transform simple Caesar shifts into a more complex and robust cipher system. Cryptographers and students studying classical ciphers utilize this utility to understand historical cryptography principles. It allows individuals to practice encrypting messages using known methods, providing a hands-on way to grasp polyalphabetic substitution theory. The calculator is useful for anyone needing to test or verify the security of text encoded with the Vigenère cipher algorithm.