[rtcweb] Use case change request: Identity in multiuser calls

[Harald Alvestrand <[e-mail]>]

In draft-ietf-rtcweb-use-cases-and-requirements, I would like to extend 
one part of the scenario "4.3.3 Video conferencing system with central 
server".

I would like to add one more paragraph:

"All participant are authenticated by the central server, and authorized 
to connect to the central server. The participants are identified to 
each other by the central server, and the participants do not have 
access to each others' credentials such as e-mail addresses or login IDs".

This is necessary in order to drive use cases that resemble Google 
Hangout, where it is a requirement that people are able to participate 
without disclosing their Google login IDs to each other.
(in the particular case of Hangout, the display name on their profile 
*is* disclosed ... but that's a different matter)

The reason I think this is important is that it feeds directly into the 
discussion of what WebRTC needs to authorize: The final source or 
destination of media, or the identity of the handler at the first hop. 
In at least the case of Hangouts, the requirement is to *not* authorize 
the final source or destination.

Not sure yet how to formulate that as a requirement, and not sure yet if 
it applies to the cases without a central server, such as 4.2.6. We may 
have to decide.

                         Harald