Additive Cipher

http://demonstrations.wolfram.com/AdditiveCipher/ The Wolfram Demonstrations Project contains thousands of free interactive visualizations, with new entries added daily. The mono-alphabetic substitution cipher provides the simplest form of cryptography, where the cipher alphabet is simply a rearrangement of the plaintext alphabet. In an additive cipher, the cipher alphabet is a shift of the plaintext alphabet. Contributed by: Shawna Martell