A system and method for a web browser to convert an unencrypted character string into a cipher-text string combines a public-key encryption algorithm with a unique and constantly changing salt key. A private “server-key”, a public “client-key” and a server session ID are generated by the server, and the client-key and the session ID are sent to the browser with the code used to encrypt the message. The session-based string can be a randomly generated set of characters which changes between established user sessions and the salt key can be formed from the server session ID string. The server contains the matching code necessary to decrypt the stream using the private key.