Zero-knowledge proof

A zero-knowledge proof is a way to prove that something is true without sharing secret information. It’s a technology, not a cryptocurrency or token.

What is a zero-knowledge proof?

A zero-knowledge proof involves two parties. The prover creates the proof. The verifier checks whether it’s valid.

The prover uses secret information and agreed-upon rules for calculations. The verifier doesn’t need to receive that secret information. A well-designed proof verifies only the chosen claim and doesn’t reveal any additional secret information.

An example of a zero-knowledge proof

Suppose someone needs to prove they’re at least 18 years old. With a zero-knowledge proof, they can do this without showing their date of birth.

This only works if the age information is reliable, for example, if it comes from a digitally signed ID. So a proof doesn’t automatically make self-reported information true.

Why are zero-knowledge proofs important in crypto?

Privacy-focused crypto applications can use proofs to show that a transaction follows the rules. This means they don’t have to make all the transaction details public.

Scaling solutions also use this technology. A zk-rollup can use a single validity proof to show that a group of transactions was processed correctly. The base blockchain then doesn’t have to repeat all those calculations.

That’s why you’ll see the term in articles about privacy, digital identity, and scalability. ZK doesn’t automatically mean that transactions are completely anonymous: public addresses and other information may still reveal details. Proofs can also require a lot of computing power and memory.