Just Kill Me..
and entails extending IMAP (b.1986) to create secure, authenticated group chat.
No, please, make it stop.
It's like these people who think PKI is about indentity as opposed to securing a two-way communication and we end up with the shitshow that is is EV,
STOP making protocols do things they're not intended to do. Just stop. You overcomplicate the protocol and it ends up being useless at the thing you wanted to do anyway, and nobody will use it.
There are plenty of secure "chat" protocols that work very well, we don't need this. Also nothing but anybody who thinks people use Facebook for chat in great numbers is a tool. Go back to sleep.