I have been working on an Android App quite a while now, starting from a simple idea.
A messenger where messages travel directly between phones with no servers in between. Using direct WebRTC encrypted connections (SRTP/DTLS), there are no servers that stores, reads, or relays content. Group chats use a gossip protocol where members relay to other members.
The only infrastructure the app touches is a signalling relay to set up the connection (no message content), a push notification to wake up a sleeping phone (also no content), and a TURN relay for restricted networks (encrypted packets only).
I wrote a detailed white paper explaining the full architecture: https://www.mindtheclub.com/white-paper.html
The app is in Open Testing on Google Play (1,000 tester cap): https://www.mindtheclub.com/beta-signup.html
I’m interested in this community's perspective on whether the architecture holds up.
i won't comment on your tor-to-cloudflare-to-google design because i haven't looked at it and don't expect i'll make time to anytime soon.
Lots of similar things are able to avoid cloud services entirely; your perceived need to use them is driven by your so-called "server-free" design which isn't really free of servers at all because, as the saying goes, "there is no cloud, just other people's computers".
You could also use Google's push notifications but make them optional, btw. Making the protocol have a hard dependency on that is a choice you are making.
having users' devices transmit fixed identifiers while moving around is terrible for privacy / great for surveillance, and firmly in the category of things which i not only do not recommend but implore people to not build. please don't.
But your landing page is still up, and still making unsubstantiated claims and encouraging users to trust in (aka rely on) a thing which is totally half baked. You are still peddling snake oil. You should fix that.
I see, now we're getting down to it :)
A few questions on that front:
About cloud services: The core idea behind the "server-free" design is to keep users' messages from ever touching the cloud. Wake-up notifications and signalling (metadata) do require some kind of cloud service before the peer-to-peer connection is established. The only way to avoid third-party cloud services entirely would be to build your own, though I'm not sure that would really change how the dependency is perceived from a client's perspective.
About Bluetooth: Messages are still end-to-end encrypted, anyway It’s a user choice, you don’t have to use it, and I found a lot of people appreciate this feature, Briar has it.
About the landing page: At least I’m clear I’m still in beta, evolving situation, anyway I’m working on the right wording.
About the questions:
given that the messages are encrypted, what is the advantage that you perceive in using "the cloud" (servers) only for signaling rather than transmitting the actual ciphertext through them? Wouldn't your "cloud" servers see "just the metadata" either way?
It saves some costs for you, but it comes at the cost of requiring users to be online at the same time to exchange messages... is there some other advantage that you see?
ah, so it will be the kind of "free open source software" which can only be used via Google Play 🙄
that's another thing you should inform potential users of explicitly, if you want to be honest.