> Work out a zero knowledge way to verify age, and implement it
is it feasible? is it likely given government's desire for more surveillance?
personally I think the best approach is to empower parents - require ISP's and ISP supplied routers have means to filter, ensure child friendly filtered SIM cards are easily available etc.
Yes, it is feasible. The EU has been working on it for a while as part of the EU Digital Identity Wallet project. Parts of it, including zero knowledge age verification, are undergoing large field trials in several countries.
Briefly, here's how it works.
• Your government can issue you a digital copy of government identity documents. This copy is cryptographically bound to a key that it stores in a hardware security module that you provide.
In the reference implementation and the implementations undergoing field testing the supported hardware security modules are the security modules in Apple mobile devices and in many Android devices. They plan to support more, such as stand alone smart cards and external security keys like YubiKeys.
• There's a zero knowledge protocol that lets you demonstrate to a website that (1) you have a digital copy of a government ID document that is bound to the hardware security module of your device and that you were able to unlock that hardware security module, and (2) that ID document says your birthday is far enough in the past that you meet the site's age requirement.
You should ask a parent how well they work. I have spoken to a few and as a rule, the restrictions are so poorly implemented that they either block nothing or make the application impossible to use.
is it feasible? is it likely given government's desire for more surveillance?
personally I think the best approach is to empower parents - require ISP's and ISP supplied routers have means to filter, ensure child friendly filtered SIM cards are easily available etc.