Re:Abusing WebRTC to reveal coarse location data in Signal
by lxgr on Thursday May 21, 2020 @08:10AM
(#23257431)
The confusion seems to stem from two kinds of privacy goals here: Metadata privacy towards third parties (i.e. who is calling who; Signal explicitly does not provide this) and reciprocal location privacy of two calling parties (i.e. I don't know where I am called from and vice versa, only who I am talking to).
Signal's conscious choice is to interpret a user adding another as a contact as an implicit signal to mark them trustworthy enough to forfeit the second kind of privacy in exchange for better voice quality (latency and bandwidth) as well as to lighten the strain on their resources.
EDIT: What I meant by this, as upon re-reading it seems unclear, is that the privacy as I understand it is not supposed to protect one party from the other party with which they are communicating, but rather conceal the conversation from third parties.