Welcome to the resource topic for 2022/270
Title:
Efficient NIZKs and Signatures from Commit-and-Open Protocols in the QROM
Authors: Jelle Don, Serge Fehr, Christian Majenz, Christian Schaffner
Abstract:Commit-and-open Sigma-protocols are a popular class of protocols for constructing non-interactive zero-knowledge arguments and digital-signature schemes via the Fiat-Shamir transformation. Instantiated with hash-based commitments, the resulting non-interactive schemes enjoy tight online-extractability in the random oracle model. Online extractability improves the tightness of security proofs for the resulting digital-signature schemes by avoiding lossy rewinding or forking-lemma based extraction. In this work, we prove tight online extractability in the quantum random oracle model (QROM), showing that the construction supports post-quantum security. First, we consider the default case where committing is done by element-wise hashing. In a second part, we extend our result to Merkle-tree based commitments. Our results yield a significant improvement of the provable post-quantum security of the digital-signature scheme Picnic. Our analysis makes use of a recent framework by Chung et al. for analysing quantum algorithms in the QROM using purely classical reasoning. Therefore, our results can to a large extent be understood and verified without prior knowledge of quantum information science.
ePrint: https://eprint.iacr.org/2022/270
Talk: https://www.youtube.com/watch?v=kLCwUvDv7ME
Slides: https://iacr.org/submit/files/slides/2022/crypto/crypto2022/133/slides.pdf
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