zk-STARK

A zk-STARK is a zero-knowledge proof that is scalable and transparent: it needs no trusted setup, relying only on hash functions and public randomness instead of secret parameters. That removes the toxic-waste risk associated with zk-SNARKs, and the underlying assumptions are generally regarded as resistant to quantum attacks because they do not depend on elliptic curves. The trade-off is size — STARK proofs are considerably larger, so posting and verifying them on-chain costs more, although verification still scales far better than re-executing the work. Several Ethereum rollups use STARKs to prove batches of transactions. In practice, choosing between SNARKs and STARKs is an engineering decision about proof size, prover cost, setup assumptions and long-term cryptographic risk.