What is a zero-knowledge proof (ZKP)?

A zero-knowledge proof lets a prover convince a verifier that a statement is true without giving the verifier any further information; the interactive form is a special challenge-response procedure whose transcript the verifier cannot use to convince a third party, and the non-interactive form is derived from it and is often called a signature.

In SSI, ZKPs make proofs unlinkable: a verifier learns only that the claim holds, not the issuer's signature it could correlate across presentations.

Go deeper:

• Zero-knowledge proof (Wikipedia) — convincing a verifier of a statement without revealing anything else.