Publicly Verifiable Proofs from Blockchains

Alessandra Scafuro; Luisa Siniscalchi; Ivan Visconti

Paper 2019/066

Publicly Verifiable Proofs from Blockchains

Alessandra Scafuro, Luisa Siniscalchi, and Ivan Visconti

Abstract

A proof system is publicly verifiable, if anyone, by looking at the transcript of the proof, can be convinced that the corresponding theorem is true. Public verifiability is important in many applications since it allows to compute a proof only once while convincing an unlimited number of verifiers. Popular interactive proof systems (e.g., $\Sigma$-protocols) protect the witness through various properties (e.g., witness indistinguishability (WI) and zero knowledge (ZK)) but typically they are not publicly verifiable since such proofs are convincing only for those verifiers who contributed to the transcripts of the proofs. The only known proof systems that are publicly verifiable rely on a non-interactive (NI) prover, through trust assumptions (e.g., NIZK in the CRS model), heuristic assumptions (e.g., NIZK in the random oracle model),specific number-theoretic assumptions on bilinear groups or relying on obfuscation assumptions (obtaining NIWI with no setups). In this work we construct publicly verifiable witness-indistinguishable proof systems from any $\Sigma$-protocol, based only on the existence of a very generic blockchain. The novelty of our approach is in enforcing a non-interactive verification (thus guaranteeing public verifiability) while allowing the prover to be interactive and talk to the blockchain (this allows us to circumvent the need of strong assumptions and setups). This opens interesting directions for the design of cryptographic protocols leveraging on blockchain technology.

Note: Compared to previous versions, this one includes improved definitions. Moreover a few typos have been corrected.

Metadata

Available format(s): PDF
Publication info: A minor revision of an IACR publication in PKC 2019
Keywords: Non-interactive Witness Indistinguishability Blockchain public verifiability NIZK WI
Contact author(s): luisa siniscalchi88 @ gmail com
History: 2019-02-09: revised; 2019-01-25: received; See all versions
Short URL: https://ia.cr/2019/066
License: CC BY

BibTeX

@misc{cryptoeprint:2019/066,
      author = {Alessandra Scafuro and Luisa Siniscalchi and Ivan Visconti},
      title = {Publicly Verifiable Proofs from Blockchains},
      howpublished = {Cryptology {ePrint} Archive, Paper 2019/066},
      year = {2019},
      url = {https://eprint.iacr.org/2019/066}
}