There’s lots of cryptographic type approaches where the entity validating you is air-gapped from the entity certifying your age.
But if you don’t trust them it’s not hard to figure out a scratchcard system where for, say, £1 cash your local newsagent checks your ID and lets you pick a card that you scratch off to get a code that you can then use to obtain a cryptographic token online signed by a recognized CA. Neither the newsagent nor the card issuer have any way of tying you to that code, and if you don’t like the idea of using the same token on multiple sites you can always buy more. Of course you’d also have the option of obtaining codes online, but there’s something I think people would find reassuring about the existence of a visible physical gap.
There’s lots of cryptographic type approaches where the entity validating you is air-gapped from the entity certifying your age.
But if you don’t trust them it’s not hard to figure out a scratchcard system where for, say, £1 cash your local newsagent checks your ID and lets you pick a card that you scratch off to get a code that you can then use to obtain a cryptographic token online signed by a recognized CA. Neither the newsagent nor the card issuer have any way of tying you to that code, and if you don’t like the idea of using the same token on multiple sites you can always buy more. Of course you’d also have the option of obtaining codes online, but there’s something I think people would find reassuring about the existence of a visible physical gap.