Simpler, "pen and paper" style ciphers and substitution-style codes - all automated and running in your browser. Let's say that you need to send your friend a message, but you don't want another person to know what it is. You can use a full-blown encryption tool, such as PGP. If the message isn't that important or if it is intended to be decrypted by hand, you should use a simpler tool. This is a