Currently it encrypts the stream using TLS, just swap out that encryption key with one only known to the participants. Generate and share a symmetric key for th

Currently it encrypts the stream using TLS, just swap out that encryption key with one only known to the participants. Generate and share a symmetric key for the call (under the hood, of course; users should never have to deal with this unless they actively seek out the key verification feature) and things would work exactly the same from there, the server just needs to forward traffic. It might currently not work in a browser because native TLS is way faster than doing the crypto in JavaScript, but in principle it should be equally heavy whether you make it end-to-end-encryption or encrypt-to-server.