Add encryption strategy to streams

[haghighatcs]

Streamer can easily be abused for pirating content, in particular copyrighted music.
a very basic, yet quite effective method is to encrypt the sensitive assets.
we can encrypt the mp3 contents server-side using some key, send it to the client, and let the client's js code decrypt and play it.
the client can still download the encrypted mp3 file, but without the proper decryption algorithm it's a useless file.

[reyraa]

This is a valid concern and I think we should further discuss it as a Discussions section here. Once we came to a conclusion we can update the ticket description and implement it.