Paper 2023/1381

Sometimes You Can’t Distribute Random-Oracle-Based Proofs

Jack Doerner, Technion – Israel Institute of Technology
Yashvanth Kondi, Aarhus University
Leah Namisa Rosenbloom, Brown University

We investigate the conditions under which straight-line extractable NIZKs in the random oracle model (i.e. without a CRS) permit multiparty realizations that are black-box in the same random oracle. We show that even in the semi-honest setting, any MPC protocol to compute such a NIZK cannot make black-box use of the random oracle or a hash function instantiating it if security against all-but-one corruptions is desired, unless the size of the NIZK grows with the number of parties. This presents a fundamental barrier to constructing efficient protocols to securely distribute the computation of NIZKs (and signatures) based on MPC-in-the-head, PCPs/IOPs, and sigma protocols compiled with transformations due to Fischlin, Pass, or Unruh. When the adversary is restricted to corrupt only a constant fraction of parties, we give a positive result by means of a tailored construction, which demonstrates that our impossibility does not extend to weaker corruptions models in general.

Available format(s)
Cryptographic protocols
Publication info
Threshold CryptographyMultiparty ComputationStraight-line ExtractionNIZKZero-knowledgeSignatures
Contact author(s)
j @ ckdoerner net
yash @ ykondi net
leah_rosenbloom @ brown edu
2023-09-18: approved
2023-09-14: received
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      author = {Jack Doerner and Yashvanth Kondi and Leah Namisa Rosenbloom},
      title = {Sometimes You Can’t Distribute Random-Oracle-Based Proofs},
      howpublished = {Cryptology ePrint Archive, Paper 2023/1381},
      year = {2023},
      note = {\url{}},
      url = {}
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