Consider the level privacy of an interoperable / federated network is only as good as the node with the lowest level of privacy. The moment you connect to Meta infra, you’re feeding it data, including but not limited to who you talked with, when you online, your message frequency, and possibly a whole lot more. Then they can start linking other bits to form a complete profile of you.
It is just slightly better than installing WA., and also part of tge reasons why many Mastodon and Lemmy server refuse to federate with Meta Threads.
Key? Oh, welcome to the land of GPG/OTP where platform and protocol doesn’t matter. Good luck finding a friend willing to deal with this just to talk to you though. And loose some important security features like forward secrecy and double ratchet.
So you want self hosted? And what you mean by changing the encryption? Changing the encryption protocol and encryption algorithm are two different thing. OMEMO is kind of de facto for XMPP. Last I checked it seems doesn’t let you choose the cipher suite like TLS 1.2 does. You can spin another if you have the capability to do so but not recommend.
There is always a cost to security. How much you and your recipent ready to pay?
And, what you mean by “secure”? E2EE is basic. How about meta data? Or resilient to DPI? How about correlation attacks? Then the directory server. And the operator of the server. Where they located can be a factor too.
There can be a milion factors that can contribute to security. You can have it all but I don’t know if such thing exist or not. For each factor, you gain some security but loss some in other places. You need to pick and choose what you need.
Actually it is more than a local problem. Since Recall shipped with opt-out, means every computer will have this enabled. Even if you truned it off, the computer on the other end may still capture your data.
Say you said something here, regret about and delete it, but right before a user have Recall enabled see it and can just dig out your now deleted comment. Not good. This applies to HIPAA data or not.
This is essentailly a local search engine that index everything you see and others said in near real time, without repecting robots.txt.