@Landy_Dan The FOG CA was introduced to secure the connection between fog-client software and the FOG server. We use certificate based state of the art encryption for that. But you need to know that it is a self signed CA and not derived from an official authority.
Not sure if it’s wise (and even possible) to use that for your RADIUS project. Give it a try and see how far you get. Start by taking a look at all the certificate stuff in /opt/fog/snapins/ssl/ on your FOG server.