Cardano achieves on-chain selective disclosure via ZK proofs at $0.24, with Groth16 SNARK verification in Plutus V3 Aiken enabling privacy without sidechains.

According to @ItsDave_ADA, a new demo on the Cardano blockchain showcases the use of zero-knowledge (ZK) proofs for privacy-preserving age verification. The system allows users to prove they are 18 or older without sharing personal data like name, birth year, or photo. Utilizing Groth16 proofs, the Plutus V3 validator processes transactions entirely on-chain, eliminating the need for sidechains or off-chain verification. This innovation enables secure, reusable credentials for age-restricted services such as purchasing alcohol, enhancing privacy and utility.