Bolt: Faster SNARKs from Sketched Codes

We introduce Bolt, a new Multilinear Polynomial Commitment Scheme (MLPCS) designed for high-performance SNARKs. Bolt is geared towards SNARKs for large computations, in which prover speed is paramount but one can afford slightly larger proofs. The construction is based on the code-switching paradigm; our core technical contribution is a new "proof-system friendly" error-correcting code with extremely efficient encoding both asymptotically and concretely.

A theory-oriented instantiation of Bolt achieves a commitment time of approximately (3+)*N field additions plus a Merkle Tree hash computation of size (1+)*N field elements, where N is the size of the multilinear polynomial and >0 is arbitrarily small. The prior state-of-the-art, Blaze (Brehm et al., Eurocrypt 2025) used 8N additions and a 4N size Merkle hash.

Concretely efficient instantiations of Bolt demonstrate that these asymptotic gains translate into substantial real-world speedups. Our benchmarks show that for N=2^30 over the field GF(2^32) Bolt's commitment time is roughly 3-4x faster than Reed-Solomon based schemes, depending on the specific parameterization. In the slower variant, the proof-size is 2MB. Bolt also offers better commitment time and especially proof size compared to recent linear-time schemes. For example, its commitment time is about 20% faster than Brakedown (Golovnev et al., Crypto 2023) with a 5-15x smaller proof.