A server sends information to a client that allows the client to establish a first key at the client. The server then receives a session ID that has been encrypted using the first key. The first key is then established at the server, which can then decrypt the session ID using the first key. After the server validates the session ID, it determines a second key that is different from the first key. The server then receives the session ID encrypted with the second key, and decrypts the session ID encrypted with the second key.