i'm only half joking. adding zkps to http requests is probably the correct privacy preserving technical solution that could be built into something sensible.

the bigger issue is that lawmakers are thinking in terms of smartphones, tablets and commercial pcs as shrink wrapped media consumption devices with a setup step... not protocol level support that preserves parts of computing and the internet they don't even really know exists. seems like the ietf should have lobbyists or something.

ZKPs don't buy anything, since an online service can sell them by the thousand and you're just trusting the client that it belongs to the actual user. You might as well just do "User-Age-Category: 18plus" then and save a headache.