Affine Cipher - Encrypt

The Affine Cipher equation encrypts a string using the Affine cipher method and returns a string of ciphertext. 

INSTRUCTIONS: Enter the following

• (p) Plaintext - the message you wish to encrypt
• (a_k) Key 1
• (b_k) Key 2

Ciphertext (C): The encryption returns a string of ciphertext

The Math / Science

First, convert your string of letters into numbers corresponding to their position in the alphabet (A = 0, B = 1, C = 2, etc...).

Then, plug each number (representing a letter) into the formula below (p = number, a_k = key1, b_k = key2).

C = [(a_k x p) + b_k] mod 26

This formula will result in a list of numbers; take these numbers and convert them back into letters based on their position (0 = A, 1 = B, 2 = C, etc...).

The resulting character string is your ciphertext.