from tcs results, this one sounds the most insane to me. ok, eps is small, but now the floodgates have opened
Helger Lipmaa
@helger.bsky.social
598 followers 292 following 234 posts
Cryptography professor at the University of Tartu, Estonia. Zero-Knowledge. SNARKs.
![Abstract. Modern cryptography relies on the intractability of computational problems. We present an approach to building cryptography from a new source of hardness: .
Our main result is a construction of succinct non-interactive arguments (SNARGs) for NP under a new, but natural, assumption on the hardness of proving lower bounds in proof complexity. Specifically, our assumption states that it is impossible to prove, within a weak bounded arithmetic theory, the correctness of certifying hard tautologies against Extended Frege. This assumption is inspired by an informal mathematical challenge proposed by Razborov [Ann. Math. ’15], and can be viewed as a generalization of an unconditional unprovability result due to Krajíček and Pudlák [J. Symb. Log. ’89].
Our construction is a simple variant of the SNARG construction of Jin, Kalai, Lombardi, and Vaikuntanathan [STOC ’24]. While the soundness of their construction was proven only for a subclass of NP, we prove its soundness for all of NP under our assumption. At the heart of our result is the observation that cryptographic reasoning is simple in a formal sense: the security proof of most cryptographic primitives can be formalized in a weak theory. In particular, we show how to formalize the scheme of Jin et al. in Jeřábek’s theory APC₁ [J. Symb. Log. ’07], a weak theory of bounded arithmetic.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:fwa55bujvdrwlwlwgqmmxmuf/bafkreif65gqm72rwqu4hbbsls5zcmukpreglvia4256ujkjn65h7yd4e7a)
![Abstract. We study the inherent barriers to constructing non-adaptively sound succinct non-interactive arguments (SNARGs) for NP with a CRS whose length is sublinear in the witness length. Our results cover both the standard SNARGs and SNARGs with an additional updatable feature (i.e. incrementally verifiable computation for NP).
- For updatable SNARGs, we show a black-box separation from falsifiable assumptions for uniform polynomial-time reductions, assuming sub-exponential hardness of learning with error.
- For general SNARGs, we show a black-box separation from falsifiable assumptions for non-uniform polynomial-time reductions that only non-adaptively make an instance-size-independent number of queries to the adversary, assuming the existence of sub-exponentially secure super-bit generators. We observe that all known SNARG constructions from polynomial hardness of standard assumptions have 1-query soundness reductions. Thus, our result complements existing constructions.
Previously, the seminal work [Gentry-Wichs, STOC’11] showed a black-box separation of SNARGs from falsifiable assumptions in the adaptive soundness setting. We explore whether any barriers exist in the non-adaptive setting. To obtain our result, we derive a simulation lemma for unbounded polynomial-length auxiliary inputs assuming super-bit generators.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:fwa55bujvdrwlwlwgqmmxmuf/bafkreihkoz3n3onokq2srb3mvt4tyhummpfk77fee64jdjspbwq3d4y64e)
