Zero Knowledge Proof
Prove your age without revealing it
Zero Knowledge Proof of Age
In cryptography, a zero-knowledge proof is a method that lets one person (the prover) show another person (the verifier) that they know a certain secret — without actually revealing the secret itself.
Normally, if you want to prove you know something, you can just show it. But with a zero-knowledge proof, the goal is to prove that you know it, without giving away any information beyond that fact.
In this example, I (the holder) want to prove that I am over 18 years old without revealing my actual age.
To do that, I ask a trusted authority (the issuer) to create a certificate for me. This certificate contains a special proof — a kind of cryptographic “challenge and response” that can be checked mathematically.
When I show this proof to someone (the verifier), they can confirm that I’m over 18 but they cannot see or calculate my real age. That’s the power of a zero-knowledge proof.
(Source: Wikipedia)
ℹ️ How it works: This implementation uses hash chaining. The prover creates a chain of hashes based on their actual age, then reveals only a portion of that chain (the "challenge") that proves they're above the threshold age. The verifier can hash the challenge the required number of times and check if it matches the proof, without ever learning the actual age.