https://docs.google.com/spreadsheets/d/1-UlA4-tslROBDS9IqHal...
We also only assume the published Signal binaries match the published source code. Moxie and team have exclusive control of the signing keys and Moxie said he will fight any third parties like F-droid doing from-source signed binaries outside the Google/apple ecosystems in spite of the accountability and removed SPOF it would offer.
If you choose to use a non Google/Apple platform or a freedom-respecting architecture like RISC-V or OpenPOWER you don't get to be on the Signal network.
This eliminates me from being able to use Signal. Talked to moxie at length about this but in the end he repeatedly admits he has no problem cutting off the few to enforce his vision for the many. He also frequently implies he sees himself as the only entity worthy of running the world's communications systems.
He is a smart guy and means well, but he is naive. Benevolent dictators are always replaced by less benevolent ones eventually. There is nothing stopping what happened to WhatsApp happening to Signal. You also have to trust the pinky swear offered by the Signal Foundation that they won't dump the keys from their SGX enclaves using any of a myriad of design flaws, and that they, their ISP, datacenters, and any three letter orgs tapping them will all throw away all the TVP/IP level metadata that centrally flows to their systems.
With Matrix OTOH, if those that host a given set of binaries/servers go evil or we simply want control of our metadata for sensitive channels, we can just use one of the alternative independent clients or a fork, switch to our own server or one run in a country or by an entity we trust more. We also still will be able to reach our social graph, just like switching an email provider.
Democratic control is messy, but I will take it over a benevolent dictator any day.
As for documentation, matrix.org documents the API and design choices of Matrix extensively and they welcome people making alternative clients and bridges to other networks because they believe the only safe and sustainable network services are open ones.
