It is possible to create a digital ID that allows you to prove to a liquor store that you are over 21 without disclosing your actual birthday, name, or any other identifying information, by having a third party (e.g. the government) trusted by the liquor store attest to it. In this case the government signs a certificate certifying your ability to buy alcohol (for example) tied to your public key that the vendor verifies, and you show that cert to any vendor at any time and the government doesn't know and can't stop it. The problem is that government issued digital IDs are unlikely to respect your liberty and will likely give the government a way to cut you off, instead of doing it right. View quoted note →