What is zero-knowledge proof?

A zero-knowledge proof (ZKP) is a cryptographic protocol where one party (the prover) can prove to another party (the verifier) that they know a certain piece of information without revealing the information itself. Essentially, it allows the prover to demonstrate the truth of a statement without sharing the underlying details. For example, using a ZKP, an individual could prove they are over 18 without revealing their exact age. The protocol confirms only the validity of the statement (that they meet the age requirement), without disclosing the age itself.

ZKP is a privacy-enhancing technology, making them valuable for applications like identity verification, private transactions, and secure computations. For instance, ZKPs are being considered as part of secure identity verification systems in the EU under the eIDAS regulation. The aim is to allow individuals to prove certain attributes about themselves (age, residence, citizenship etc.) without disclosing more information.