I'm wondering if to prevent the possibility of a compromised SSL certificate leading to the potential for sensitive information disclosure if it might be prudent to further encrypt data being passed over SSL.
Imaginary scenario: two web applications. One is a web application, the other is an application supplying an authentication API.
The web app sends an HTTPS POST to the authentication API containing username and password. It's encrypted via SSL.
However, couldn't that data be sniffed if an attacker was to compromise the SSL cert?
My thought is to add another level of encryption -- e.g. we have an additional public/private key pair and we encrypt all the information in the POST by that as well.
That would mean that an attacker who had compromised your SSL cert would need to find an additional private key in order to break the communication.