[Secdispatch] Multicast architectures for the web

[Ben Schwartz <[e-mail]>]

Regarding draft-krose-multicast-security, I think the most productive step
would be to start with an architecture that sits on top of WebTransport in
unmodified browsers.  WebTransport's support for unreliable datagrams opens
up a lot of novel possibilities for application-layer multicast (e.g.
holding less state at the splitter, backfiling lost segments directly from
the origin), and raises some interesting questions about how to implement
content security most naturally.  This can all be done without browser
changes.

If a system like this can be clearly defined, deployed, and measured, I
think that greatly increases the likelihood of some of this functionality
being moved down into the web itself.  There's a long history of page-layer
innovations being moved into the browser (e.g. crypto in JS -> WebCrypto,
asm.js -> WebAssembly), and experiments with solutions within the page can
help us to identify the bottlenecks that really need to be alleviated.

--Ben Schwartz