So... can PFS be enabled in Matrix at all?

Continuing the discussion from IM/RTC: Perfect Forward Secrecy Requirement:

We should figure out how exactly to do this and consider documenting it on the site, according to Matthew it should be possible to set the session duration to 1, possibly with a custom state upon room creation? I also just found out that it doesn’t even seem like knows whether this is possible in existing rooms:


The other thing we should probably document is the default session length. I read it was 100 messages but I’m not totally sure, but that would mean that Matrix provides forward secrecy, just in batches of 100 messages instead of per-message, which is still probably better than alternatives which lack forward secrecy in any form.

Not sure if it makes sense to document this when it all sounds very experimental. It may create a false sense of security. I would refrain from it unless someone who actually has the authority and knowledge of the cryptography to say something about this has commented on this.