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Brakedown: Linear-time and field-agnostic SNARKs for R1CS

Authors:
Alexander Golovnev , Georgetown University
Jonathan Lee , Nanotronics
Srinath Setty , Microsoft Research
Justin Thaler , Georgetown University
Riad Wahby , Carnegie Mellon University
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DOI: 10.1007/978-3-031-38545-2_7 (login may be required)
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Presentation: Slides
Conference: CRYPTO 2023
Abstract: This paper introduces a SNARK called Brakedown. Brakedown targets R1CS, a popular NP-complete problem that generalizes circuit-satisfiability. It is the first built system that provides a linear-time prover, meaning the prover incurs O(N) finite field operations to prove the satisfiability of an N-sized R1CS instance. Brakedown’s prover is faster, both concretely and asymptotically, than prior SNARK implementations. It does not require a trusted setup and may be post-quantum secure. Furthermore, it is compatible with arbitrary finite fields of sufficient size; this property is new among built proof systems with sublinear proof sizes. To design Brakedown, we observe that recent work of Bootle, Chiesa, and Groth (BCG, TCC 2020) provides a polynomial commitment scheme that, when combined with the linear-time interactive proof system of Spartan (CRYPTO 2020), yields linear-time IOPs and SNARKs for R1CS (a similar theoretical result was previously established by BCG, but our approach is conceptually simpler, and crucial for achieving high-speed SNARKs). A core ingredient in the polynomial commitment scheme that we distill from BCG is a linear-time encodable code. Existing constructions of such codes are believed to be impractical. Nonetheless, we design and engineer a new one that is practical in our context. We also implement a variant of Brakedown that uses Reed-Solomon codes instead of our linear-time encodable codes; we refer to this variant as Shockwave. Shockwave is not a linear-time SNARK, but it provides shorter proofs and lower verification times than Brakedown, and also provides a faster prover than prior plausibly post-quantum SNARKs.
BibTeX
@inproceedings{crypto-2023-33262,
  title={Brakedown: Linear-time and field-agnostic SNARKs for R1CS},
  publisher={Springer-Verlag},
  doi={10.1007/978-3-031-38545-2_7},
  author={Alexander Golovnev and Jonathan Lee and Srinath Setty and Justin Thaler and Riad Wahby},
  year=2023
}