[NorwegianDude]

The proper way to implement it is to issue digital IDs and use ZK proofs to verify the age. That way the service doesn't know anything other that the fact that you have an official digital ID and that you are at least a certain age. The ID issuer does not need to be involved in anything other than issuing the ID, making it perfect when it comes to privacy, while still fulfilling the goal of having an age limit.

If this is built on open standards, so that anyone can use it for free, it would be a big positive step forward for everyone.

[mrob]

Zero knowledge proofs are unusable for age verification because they're impossible to revoke. One person can share their ID and everyone else can use it.

[orwin]

If your country has a digital ID, it is possible.

[mrob]

If it's possible to revoke then by definition it's not zero knowledge. Revocation status is knowledge.

[orwin]

Sorry, i wasn't clear. If you have digital ID, you can emit time-limited certificates.