Paper 2017/330

Distinguisher-Dependent Simulation in Two Rounds and its Applications

Abhishek Jain, Yael Tauman Kalai, Dakshita Khurana, and Ron Rothblum


We devise a novel simulation technique that makes black-box use of the adversary as well as the distinguisher. Using this technique we construct several round-optimal protocols, many of which were previously unknown even using non-black-box simulation techniques: - Two-round witness indistinguishable (WI) arguments for $\NP$ from different assumptions than previously known. - Two-round arguments and three-round arguments of knowledge for $\NP$ that achieve strong WI, witness hiding (WH) and distributional weak zero knowledge (WZK) properties in a setting where the instance is only determined by the prover in the last round of the interaction. The soundness of these protocols is guaranteed against adaptive provers. - Three-round two-party computation satisfying input-indistinguishable security as well as a weaker notion of simulation security against malicious adversaries. - Three-round extractable commitments with guaranteed correctness of extraction from polynomial hardness assumptions. Our three-round protocols can be based on DDH or QR or N^th residuosity and our two-round protocols require quasi-polynomial hardness of the same assumptions. In particular, prior to this work, two-round WI arguments for NP were only known based on assumptions such as the existence of trapdoor permutations, hardness assumptions on bilinear maps, or the existence of program obfuscation; we give the first construction based on (quasi-polynomial) DDH. Our simulation technique bypasses known lower bounds on black-box simulation [Goldreich-Krawcyzk'96] by using the distinguisher's output in a meaningful way. We believe that this technique is likely to find more applications in the future.

Note: Three round protocols have been updated.

Available format(s)
Cryptographic protocols
Publication info
A minor revision of an IACR publication in CRYPTO 2017
input-delayedweak zero knowledgestrong witness indistinguishabilitywitness hidingtwo roundsinput indistinguishable computation
Contact author(s)
dakshita @ cs ucla edu
2017-12-01: last of 4 revisions
2017-04-17: received
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Creative Commons Attribution


      author = {Abhishek Jain and Yael Tauman Kalai and Dakshita Khurana and Ron Rothblum},
      title = {Distinguisher-Dependent Simulation in Two Rounds and its Applications},
      howpublished = {Cryptology ePrint Archive, Paper 2017/330},
      year = {2017},
      note = {\url{}},
      url = {}
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