At what stage of the SSL/TLS handshake is the DHE and RSA used and what is the purpose of using a pre-master secret when you could just use RSA to exchange the symmetric key (i.e. AES) for further communications. I am confused how DHE, AES and RSA fuse into the SSL/TLS handshake process. Is there a handshake with purely RSA, purely DHE or both.
You can use RSA to exchange the keys, But the problem is, it does not provide perfect forward security. This is what may happen if you use RSA for key exchange. If someone is able to store your SSL session and if he can get the server private key, He can get the secret key generated by the SSL session. So he can decrypt the entire SSL session.