I don't understand. If Eve (who we don't know) adds data like location, age, interests to her profile on our Dave, people will want to access her profile on Dav

I don't understand. If Eve (who we don't know) adds data like location, age, interests to her profile on our Dave, people will want to access her profile on Dave. This creates an incentive for Eve to aggregate as much data on as many people as possible. Are you saying that nobody can know which Dave we're talking about unless we identify him as Dave-with-cell-5551234567? I don't think that's true, since human social circles are pretty easy to figure out; see the humorous hypothetical collection of data about US Founding Fathers. http://www.newenglandhistoricalsociety.com/phone-spying-paul-revere-and-colonial-social-networking/ http://www.newenglandhistoricalsociety.com/phone-spying-paul...