Basic String Cryptography

A couple of simple cryptography techniques.

These are three *very* simple codes for implementing the most rudimentary encryption method possible.

CRYPTOSHIFT.m implements a monoalphabetic shifting substitution encryption. It takes two arguements: the string to be encoded and the amount to shift each letter. To decode, shift backward the same amount you shifted forward.

CRYPTOSUBCODE.m generates, from an input string, a coded string and a key. The key represents the random substitutions made, and is used by CRYPTOSUBDECODE.m along with the encoded string to decode a string.