RTSP server with TLS and multi cast

HI Guys,
I know How to multicast with RTSP gstreamer. Actually, I know how to use TLS with RTSP. But I Need multicast with TLS In RTSP. I know TLS works with TCP and multicast works with UDP but I think maybe RTSP servers use TLS to share key for crypto and Hmac and digital signature for sending compressed frames. Please recommend me to have security with RTSP server in multicast mode.
Thanks so much.

No body can help?