PLONK

A universal and updateable zk-SNARK construction using a single trusted setup for any circuit up to a fixed size.

PLONK (Permutations over Lagrange-bases for Oecumenical Noninteractive arguments of Knowledge) redefined zero-knowledge efficiency by introducing a universal Structured Reference String (SRS). Unlike older protocols like Groth16 that require a unique ceremony for every circuit, PLONK allows developers to reuse one setup for any program. It leverages grand product checks and polynomial commitments (typically KZG) to achieve constant-size proofs (roughly 400 bytes) and sub-linear verification times. Major implementations like Aztec, Matter Labs' zkSync, and Electric Coin Co's Halo 2 utilize its flexible gate structure to scale Ethereum and private transactions.

https://eprint.iacr.org/2019/953