VigenereCipher

A library to code and decode Vigenère ciphers.
The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution.
In a Caesar cipher, each letter of the alphabet is shifted along some number of places; for example, in a Caesar cipher of shift 3, A would become D, B would become E, Y would become B and so on. The Vigenère cipher consists of several Caesar ciphers in sequence with different shift values.

Plaintext : ATTACKATDAWN
Key : LEMONLEMONLE
Ciphertext: LXFOPVEFRNHR