Age Checks That Don't Reveal Identity: Privacy Preserving Attribute Verification [pdf]
This paper proposes a system for age verification that preserves user privacy by not revealing identity. It uses cryptographic techniques like zero-knowledge proofs and digital signatures to allow a user to prove they are over a certain age without disclosing their exact birthdate or other personal information.
Background
- This paper proposes a cryptographic method that lets websites verify a user is over 18 without learning their exact birth date, name, or other identifying info.
- The problem: current age verification often requires uploading ID documents—leaking sensitive data, creating honeypot databases, chilling speech. Self-reported age checks ("click if over 18") are trivially bypassed.
- The approach uses "anonymous credentials" (zero-knowledge proofs) with a trusted issuer: a government signs a digital credential containing a birth date. The user can later prove "birthday > 2006-01-01" without revealing the actual date.
- Why it matters: several US states (Louisiana, Utah, Florida) are passing laws requiring age verification for social media and porn sites. Existing methods create major privacy risks. This paper offers a technical alternative that could satisfy regulators while preserving anonymity.