Comment by pimterry

Yes, this is possible, and not dissimilar to proposals making progress elsewhere, notably in the EU: https://ageverification.dev/av-doc-technical-specification/d....

There's a bunch of other "digital wallet" development going on in general, effectively providing digital certificate-backed identity documents and similar (driving licenses, passports). The plan for age verification is that these wallets will also be able to provide a cryptographically signed attestation of age (signed by an EU verification authority, i.e. your id-issuing government org) but with no other personal info included. Then you can present this to anybody, and they can independently verify the signature to confirm it's a recent proof-of-age attestation without knowing anything else about you.

It's still fairly early - lots of blueprints and proof-of-concepts, not yet rolled out anywhere AFAICT - but looks like a reasonable solution I think. In practice I suspect most people's experience will be a government-backed mobile app that you authenticate with once, and then it can handle verification requests on-device or show a QR code that other people can scan & verify.