You can then prevent certificate forging by forwarding a cryptographic hash of the requester identity (generated by the website client), which will be included in the cert body so the website can verify the attestation was generated for this specific request, and it cannot be randomly reused.
Of course this doesn't solve the problem of using your grandma's id to bypass age restrictions, but I think that problem is worth the cost of privacy gains from corporations not validating IDs directly and screwing up like Discord's vendor did here.
Or the certificate isn't the same every time and therefore you can generate a whole bunch of them and give them out for $2 apiece.
Or the certificate isn't the same every time and also isn't anonymous so they can trace who's doing that.
You don't have to reuse the same certificate for several requests. You can get a new one for every request, for every person who is asked to verify their age and pays you $2, and if they're actually anonymous, there's no way to know you did this. Is a rate limit part of the proposal? Can I only sign up to one adult service per week?
Unless you meant the requester's real identity, in which case... we're back to not anonymous.
> You don't have to reuse the same certificate for several requests. You can get a new one for every request, for every person who is asked to verify their age and pays you $2, and if they're actually anonymous, there's no way to know you did this. Is a rate limit part of the proposal? Can I only sign up to one adult service per week?
This is trivially easy to detect at the attestation service. If someone is trying to repeatedly (and programmatically) use the same personal ID to generate attestations for different request IDs in a short time frame, you can throttle them, flag them, revoke their cert, whatever.
What if I'm checking out all the online casinos and each one wants an age token?
I'm not defending age verification's existence in the first place btw, I don't think it's a good idea without secure protocols of central attestation for such things. But of course, governments aren't interested in solving the harder more valuable problem, they're interested in shifting the responsibility to corporations while crying foul.