Do you use Signal for chatting securely with friends and loved ones? Us too! We endorse it wholeheartedly, and rely on it for nearly all our communication.
But the vibes are deteriorating here in the US, and we should have a communications contingency plan for if Signal goes down.
You can move to any other service, but once it becomes popular enough to draw attention they might also get blocked as well. If it’s centralized, then the central servers can be blocked and it’s not longer working. If it’s decentralized and peer to peer, then the bootstrap nodes can be blocked and it’s no longer working.
Even if it’s self hosted and not advertised, the adversary can run active probes to detect banned services and block it if it detects any.
The only thing that can work reliably is something that can be concealed and can’t easily be detected.
A simple HTTPS website that runs a small blog, forum or an image board, can have a lot of bot traffic, and human traffic that makes the traffic analysis hard, it also provides plausible deniability if someone asks why you visit that site often, you can say that you are playing games or browse images there. Such website can have a secret interface that can be used as an interaction point for secure chatting (in a store and forward manner), which responds only if the requests are cryptographically signed by the participants, otherwise the server can play dumb and show a 404 error. Therefore an active prober can’t easily detect that the website hosts that interface the first place, because they cannot produce a signed request unless they manage to compromise one of the participants.
Threat analysis:
Someone should make an app that works this way. Only one tech savvy person of the given group need to set this up (preferably someone who alredy have a website), then others in the group can be invited into it and can use it without much friction.