Are Signal Messenger's servers able to see who I'm talking to?
I'm aware of Signal's "no log policy", but I'm wondering if such information is visible to the servers at all. I'm assuming "Sealed sender" is what is supposed to protect this information? If so, how effective is it?
When subpoenaed by the FBI they were only able to give the phone number, time of account creation and time of last connection
It's a phone app, you can trust it as much as you trust Google/Apple.
Of course. My inquiry was out of theoretical curiosity, and not so much anything practicaly useful for security, or privacy.
This would have to be available. The only way to avoid metadata like this is something like onion routing... Session will do that, probably your best bet if you're worried about this.
Why? If the information is not saved the information is not available.
Because to operate the service they have to know who to dispatch to, which could be monitored in real time.