[Cryptography] Anonymous age verification

[Steven M. Bellovin]

On 15 Jul 2026, at 9:23, zeb--- via cryptography wrote:

>
> The EU has implemented an anonymous age verification app (in minutes, using Claude, I'm led to believe).
> The current implementation can be bypassed (even en masse using a browser add-on).
> Disregarding motives and current implementations: is anonymous age verification possible, even in principle?
>

It's possible using zero-knowledge proofs—*if* you can provide suitable evidence to what I call an "identity provider". This is not necessarily easy, though in some places it will be easier than others. See https://www.cs.columbia.edu/~smb/papers/age-verify.pdf for details. (Also see that paper's reference 41, for a much more detailed look at how such a system could work—though that's a law paper, with a lot of US legal analysis, and has features that are not wanted here, e.g., a "deanonymization agent".)


        --Steve Bellovin, https://www.cs.columbia.edu/~smb