Whenever this comes up, this style of zero-knowledge proof/blind signature thing gets suggested. But the problem is that those only work if people care about keeping their private keys secret. It works to secure eg. “I own $1” but “I’m over 18” is less important to people and it won’t be hard for kids to get their hands on a valid anonymous signing key on the web. Because the verification is anonymous and not trackable, many kids can share the same one too, so it only takes one adult key to leak for everyone to use. It’s one of the reasons they push biometrics that at least appears to need a real human. Requiring ID has a lot of the same issues on top of being a privacy nightmare.
I’m starting to think that actual age verification is technically impossible.
Nym did some work on a zero knowledge verification system:
https://constructiveproof.com/posts/2020-03-24-nym-credentials-overview/
Whenever this comes up, this style of zero-knowledge proof/blind signature thing gets suggested. But the problem is that those only work if people care about keeping their private keys secret. It works to secure eg. “I own $1” but “I’m over 18” is less important to people and it won’t be hard for kids to get their hands on a valid anonymous signing key on the web. Because the verification is anonymous and not trackable, many kids can share the same one too, so it only takes one adult key to leak for everyone to use. It’s one of the reasons they push biometrics that at least appears to need a real human. Requiring ID has a lot of the same issues on top of being a privacy nightmare.
I’m starting to think that actual age verification is technically impossible.