WHIR: Reed-Solomon Proximity Testing with Super-Fast Verification

We introduce WHIR, a new IOP of proximity that offers small query complexity and exceptionally fast verification time. The WHIR verifier typically runs in a few hundred microseconds, whereas other verifiers in the literature require several milliseconds (if not much more). This significantly improves the state of the art in verifier time for hash-based SNARGs (and beyond). Crucially, WHIR is an IOP of proximity for constrained Reed–Solomon codes, which can express a rich class of queries to multilinear polynomials and to univariate polynomials. In particular, WHIR serves as a direct replacement for protocols like FRI, STIR, BaseFold, and others. Leveraging the rich queries supported by WHIR and a new compiler for multilinear polynomial IOPs, we obtain a highly efficient SNARG for generalized R1CS. As a comparison point, our techniques also yield state-of-the-art constructions of hash-based (non-interactive) polynomial commitment schemes for both univariate and multivariate polynomials (since sumcheck queries naturally express polynomial evaluations). For example, if we use WHIR to construct a polynomial commitment scheme for degree 222, with 100 bits of security, then the time to commit and open is 1.2 seconds, the sender communicates 63 KiB to the receiver, and the opening verification time is 360 microseconds.