[Cryptography] Anonymous age verification

[Jon Callas]

> On Jul 15, 2026, at 06:23, zeb--- via cryptography <cryptography at metzdowd.com> 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?

I think that "anonymous" is not quite the right term, what we're interested in is "unlinkable."

They're similar, in that if there's a "name" for me, even if it's some random bit string, that's a linkage. But the real property you want is that if someone gets an age verification ten times, it's impossible to know that they're done by the same person. 

There are a number of decent unlinkable systems, particularly ones based on BBS signatures. Yes, it's possible in principle to be unlinkable, and that's a good place to start looking.

	Jon