Yes. So they know the IP of the sender, and of the receiver, and they know the time, and they can contact the ISP and ask them who had these IP addresses at the

Yes. So they know the IP of the sender, and of the receiver, and they know the time, and they can contact the ISP and ask them who had these IP addresses at the given time and thus determine with certainty who communicated with whom. We used a law in the EU requiring ISPs to keep track of this. It was determined to be illegal, so many ISPs probably don't store this information anymore, but I am sure that many do, and there can be other people-- maybe someone from another country that comes to your country gets jobs at ISPs to modify their software and make it do things he wants. I don't know about this Salt Typhoon, but as I interpret it, there was an excellent secure system, and then people built some kind of front end on top of it so they could enter their orders into it, and then somebody compromised that front end and basically started getting all the data that the government could order to be gathered. I'm thinking that's going to include who has what IP. I agree though, the complexity is maybe okay. It doesn't sound like a super terrible protocol or that involved. I suppose the description I saw of it felt more convoluted. At the same, I felt that the complexity of the presentation was hiding something, which I think might well be true-- it might even have been this simple fact that the central server still has every opportunity to determine who sends things to whom.