Thank you for the links to Wikipedia and identity.com on that other thread. I’ve yet to wrap my head around how zero-knowledge proof could work for such a basic assertion as “user is of legal age”, which calls for a 0 or 1 answer. It seems very different from the examples given of polynomial computations to prove knowledge of an exponent in a complex math expression. I can’t see what could prevent any client to simply lie about the answer here.