Authentication of encoder using FMS URL

I would like to use either the FMS URL (i.e. rtmp://server/application/) or the stream name as a method of authentication.

Is it possible to restrict to an application (e.g. livepkgr) based on the FMS URL or the stream name entered in the encoder? This seems to be the method used by YouTube. If not, can the username and password for a stream be saved in a profile.xml file for use by the encoder?