There are various protocols that allow you to have privacy-enhanced chat.
Those can be either 2-party chat such as:
or multiparty chat such as:
- GOTR (2013 spec and 2008 ones)
But nowadays many protocols, alongside with Instant Messaging (IM), support multi-party video and voice exchange such as Skype and Google Hangouts. What protocols exist to ensure the security properties on applications for privacy-enhanced multi-party/teleconference application?
I am asking because teleconference applications are lag-sensitive ones and there is the real-time factor as well. Also, the data flow is stream based ones instead of message-based ones so ratcheting per message - like signal does - is a no-go (because there is no message concept, to begin with).
The common key for the VoIP group can be done via exchanging special messages and running a Group Key Authentication protocol but what about forward secrecy and the transcript integrity protection messages?
Do you know any protocols that support multi-party VoIP as well (even academic purpose-oriented ones without any practical value)?