Apart from the question of desirability of such checks in the first place: with attestations, the digital equivalent of a signed government document.
This process involves three parties:
- you
- the identity provider (the government)
- the third party (who wants to verify your age).
- You click a button that takes you to the identity provider (government e-identiy). There you log in.
- Identity provider asks you to confirm what you want to share with the third party, like your age bracket.
- The third party receives a digitally signed attestation with this information.
The proof of identity is exclusively between you and the government’s e-identity platform. The third party only gets to see what’s shared with them (like your age bracket).
Government e-identity isn’t hypothetical btw, e.g. in the Netherlands that’s DigiD.
Why? You’re using this method every time you use “Log in with Facebook”, or when you use corporate single sign-in. Logging in with “passkeys” is this. It has been widely deployed for government ID already. In fact, I remember it being used for age verification when getting prepaid sim card in Austria.