THE AFFINE CIPHER - ENCRYPTING & DECRYPTING

    My GitHub code : https://github.com/devmecha/THE_AFFINE_CIPHER

The affine cipher is a type of monoalphabetic substitution cipher, wherein each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter. The formula used means that each letter encrypts to one other letter, and back again, meaning the cipher is essentially a standard substitution cipher with a rule governing which letter goes to which. As such, it has the weaknesses of all substitution ciphers. Each letter is enciphered with the function F(x) = (ax + b) mod m, 
where modulus m is the size of the alphabet and a and b are the key of the cipher.