zk-SNARK

A zk-SNARK is a type of zero-knowledge proof that is succinct and non-interactive: the proof is very small and quick to verify, and the prover sends it once with no back-and-forth. That combination makes zk-SNARKs practical on blockchains, where every verifier pays for computation, and they underpin several privacy coins and ZK rollups. The historical trade-off is the trusted setup — a one-off ceremony that generates public parameters and produces secret leftovers, sometimes called toxic waste, which must be destroyed because anyone holding them could forge proofs. Multi-party ceremonies reduce that risk by requiring only one honest participant. zk-SNARKs also rest on elliptic-curve assumptions that are not considered quantum-resistant, one reason zk-STARKs exist alongside them.