International Association for Cryptologic Research

International Association
for Cryptologic Research


Individual Simulations

Yi Deng
DOI: 10.1007/978-3-030-64840-4_27
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Abstract: We develop an individual simulation technique that explicitly makes use of particular properties/structures of a given adversary's functionality. Using this simulation technique, we obtain the following results. 1. We construct the first protocols that break previous black-box barriers under the standard hardness of factoring, both of which are polynomial time simulatable against all a-priori bounded polynomial size distinguishers: a)Two-round selective opening secure commitment scheme. b)Three-round concurrent zero knowledge and concurrent witness hiding argument for NP in the bare public-key model. 2. We present a simpler two-round weak zero knowledge and witness hiding argument for NP in the plain model under the sub-exponential hardness of factoring. Our technique also yields a significantly simpler proof that existing distinguisher-dependent simulatable zero knowledge protocols are also polynomial time simulatable against all distinguishers of a-priori bounded polynomial size. The core conceptual idea underlying our individual simulation technique is an observation of the existence of nearly optimal extractors for all hard distributions: For any NP-instance(s) sampling algorithm, there exists a polynomial-size witness extractor (depending on the sampler's functionality) that almost outperforms any circuit of a-priori bounded polynomial size in terms of the success probability.
Video from ASIACRYPT 2020
  title={Individual Simulations},
  booktitle={Advances in Cryptology - ASIACRYPT 2020},
  author={Yi Deng},