zk-SNARK (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge)

zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge) are cryptographic proof systems that create concise, easily verifiable proofs confirming data validity without revealing the data itself, enabling both privacy and scalability in blockchain applications.

The key properties of zk-SNARKs are succinctness (proofs are small, typically just a few hundred bytes regardless of computation size), non-interactivity (the prover generates proof without back-and-forth communication with the verifier), and zero-knowledge (no information beyond the statement's validity is revealed). However, most zk-SNARK constructions require a trusted setup ceremony where initial parameters are generated, creating potential security risks if the ceremony is compromised.

zk-SNARKs enable privacy coins like Zcash where transaction amounts and participants remain confidential while maintaining verifiable network integrity, confidential DeFi protocols, and compact zk-rollup proofs for Layer 2 scaling. Their small proof size and fast verification make them efficient for on-chain verification, though proof generation is computationally intensive. The trusted setup requirement has led to development of alternative constructions like zk-STARKs that eliminate this assumption at the cost of larger proof sizes.