Zero-knowledge proof

A cryptographic proof that a statement is true which reveals nothing beyond the fact that it is true.

• The classic use is privacy: proving you are over 18, or hold enough funds, without disclosing the underlying data.
• In blockchains the bigger use is compression: a proof of a huge computation can be checked in milliseconds, far faster than redoing it.
• zk rollups use this to show Ethereum that thousands of transactions are valid with one small proof.
• Generating proofs is expensive, often thousands of times the original computation, which is driving specialised proving hardware.