Is there a self-hosted end-to-end encrypted messaging platform that also supports attaching files, images or other stuff along the messages?
It seems that OMEMO is not there yet.
In current XMPP usage, the E2EE stuff like OMEMO is only used to transfer a password. That password is used to encrypt the content which is uploaded to a http server associated (and often built into) the XMPP server. A http link is sent to the other end and that link is used to download the content.<p>The double transfer is slow, but experience has shown that direct connections between clients simply can not be made completely reliable in the current network environment.