This blogpost has been improved based on fedi discussions around it; you can find the Polish thread here, and the English thread here. I appreciate all this input!
I have recently been asked by the Panoptykon Foundation if it was possible to create an online age verification system that would not be a privacy nightmare. I highly recommend reading their piece, which dives into several issues around age verification.
I replied that yes, under certain assumptions, this is possible. And provided a rough sketch of such a system.
But before we dive into it, I have to be clear: I am not a fan of introducing online age verification systems. Privacy is just one of the many issues related to them. I dive into some of those later in this post.