The problem is, whatever tech we come up with, it'll need a "social protocol" (just as every cryptosystem needs a human element and it has to be factored in dur

The problem is, whatever tech we come up with, it'll need a "social protocol" (just as every cryptosystem needs a human element and it has to be factored in during security analysis). And right now you can just give your phone to Decorator Tim with his/her name prefilled and with no numbers, and Tim will likely just type their number. Yeey, success! Sure it would be easier to just wave your phone, show a "contact request" logo/hand-sign, but we're not there yet. And exactly because bars are loud, but garden parties are too sunny that we would need a very generic/adaptive solution. Currently it's simply solved by raw human wetware processing power, ingenuity and foresight (eg. in case of business cards). Yes, I think NFC is perfect for contacts, but it needs the social dance too. (Exactly because of the edge cases as in how do you easily accept/reject it if you can't see the screen?)