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What is a zk-SNARK?
A zk-SNARK is a kind of zero-knowledge proof that is very small and quick to check: it convinces anyone that a computation was done correctly without revealing the private inputs or redoing the work. Many designs need a one-time setup ceremony whose secret values must be destroyed afterwards.
What it means for you
Systems built on zk-SNARKs, such as some rollups and privacy tools, ask you to rely on their setup ceremony having had at least one honest participant and on the proving code being correct; a flaw in either could allow false proofs. Whether a system needs a setup, and who took part, is a concrete question you can check.
How it works
ethereum.org expands the name as Zero-Knowledge Succinct Non-Interactive Argument of Knowledge. Succinct means the proof is smaller than the secret input it covers and can be verified quickly; non-interactive means prover and verifier interact only once. Many SNARKs need a common reference string produced in a setup ceremony; anyone who kept its secret randomness could compute false proofs. Groth's 2016 construction shows how small proofs can get: three group elements, checked with three pairings. SNARKs that rely on elliptic curves inherit their exposure to future quantum computers.
Sources: ethereum.org: Zero-knowledge proofs, Groth, On the Size of Pairing-based Non-interactive Arguments (IACR ePrint 2016/260) · checked 4 October 2026
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