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Improved Quantum Lifting by Coherent Measure-and-Reprogram

Authors:
Alexandru Cojocaru , University of Edinburgh
Juan Garay , Texas A&M University
Qipeng Liu , UC San Diego
Fang Song , Portland State University
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Conference: ASIACRYPT 2024
Abstract: We give a tighter lifting theorem for security games in the quantum random oracle model. At the core of our main result lies a novel measure-and-reprogram framework that we call coherent reprogramming. This framework gives a tighter lifting theorem for query complexity problems, that only requires purely classical reasoning. As direct applications of our lifting theorem, we first provide a quantum direct product theorem in the average case --- i.e., an enabling tool to determine the hardness of solving multi-instance security games. This allows us to derive in a straightforward manner the hardness of various security games, for example (i) the non-uniform hardness of salted games, (ii) the hardness of specific cryptographic tasks such as the multiple instance version of one-wayness and collision-resistance, and (iii) uniform or non-uniform hardness of many other games.
BibTeX
@inproceedings{asiacrypt-2024-34670,
  title={Improved Quantum Lifting by Coherent Measure-and-Reprogram},
  publisher={Springer-Verlag},
  author={Alexandru Cojocaru and Juan Garay and Qipeng Liu and Fang Song},
  year=2024
}