In StarkNet, are STARK Proofs Zero-Knowledge Proofs?

STARKs are defined as Validity proofs, meaning they prove computational integrity. With Validity proofs (STARKs included), one party can prove to another that a certain computation was done correctly. With Zero-Knowledge proofs, the prover does not have to reveal any information included in the computation, except for the fact that the computation was done correctly.

Most ZK-Rollups are not really Zero-Knowledge. The mistake comes from the confusion between Validity proofs (assures computational integrity) and Zero-Knowledge proofs (assures no information is revealed).

StarkNet uses STARK Validity proofs. It is worth noting that extracting information from the proof is extremely hard – almost impossible in practice.