World Foundation researcher @dcbuilder on the future of digital identity where you can prove you're over 18 without revealing your age or prove where you live without revealing your location: "Zero-knowledge cryptography essentially allows you to make a proof about some fact or some data, without revealing the underlying data. For example, you can make a proof that I'm over 18 without revealing my age, or proof that I reside in the United States or in Europe without revealing my actual…