what matters is that the server has a unique id for you and the person you're talking to, and that id can then be mapped to the phone number that was initially collected. That's all the server needs to identify the real identity of the people you communicate with
the key point missing in the middle here though is that the IDs aren’t what matters: it’s having the ability to link those IDs
and i agree, being able to link you->your phone number->your user ID->message->recipient ID->recipient phone number->recipient as an individual is a problem
but again, sealed sender break that chain: there is cryptographically no way to link your user ID to the message you’ve sent
it’s literally impossible for them to build a social graph from your messages
It's not a question of what the server needs minimally
again, i agree… kinda… i put that there to show that you don’t actually need the sender to achieve the goal of delivering the message. it was part of the explanation of why sealed sender works, rather than a point to be made by itself
what the server could be doing if it was set up maliciously. The sealed sender does not solve this problem in any way shape of form
would you be able to explain how it doesn’t?
sealed sender divorces your user ID from any message you send… your messages can not be tied back to your user ID or phone number without having decrypted the message content
so even with a malicious server, because you can verify your client behaviour (that it derives keys, and that you can verify the message payload contains nothing outside the ciphertext which is unexpected), then even a malicious server (without IP information) doesn’t have the information necessary to infer the sender from the sent message