A New World in the Depths of Microcrypt: Separating OWSGs and Quantum Money from QEFID

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Hauptverfasser: Behera, Amit, Malavolta, Giulio, Morimae, Tomoyuki, Mour, Tamer, Yamakawa, Takashi
Format: Preprint
Veröffentlicht: 2024
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author Behera, Amit
Malavolta, Giulio
Morimae, Tomoyuki
Mour, Tamer
Yamakawa, Takashi
author_facet Behera, Amit
Malavolta, Giulio
Morimae, Tomoyuki
Mour, Tamer
Yamakawa, Takashi
contents While in classical cryptography, one-way functions (OWFs) are widely regarded as the "minimal assumption," the situation in quantum cryptography is less clear. Recent works have put forward two concurrent candidates for the minimal assumption in quantum cryptography: One-way state generators (OWSGs), postulating the existence of a hard search problem with an efficient verification algorithm, and EFI pairs, postulating the existence of a hard distinguishing problem. Two recent papers [Khurana and Tomer STOC'24; Batra and Jain FOCS'24] showed that OWSGs imply EFI pairs, but the reverse direction remained open. In this work, we give strong evidence that the opposite direction does not hold: We show that there is a quantum unitary oracle relative to which EFI pairs exist, but OWSGs do not. In fact, we show a slightly stronger statement that holds also for EFI pairs that output classical bits (QEFID). As a consequence, we separate, via our oracle, QEFID, and one-way puzzles from OWSGs and several other Microcrypt primitives, including efficiently verifiable one-way puzzles and unclonable state generators. In particular, this solves a problem left open in [Chung, Goldin, and Gray Crypto'24]. Using similar techniques, we also establish a fully black-box separation (which is slightly weaker than an oracle separation) between private-key quantum money schemes and QEFID pairs. One conceptual implication of our work is that the existence of an efficient verification algorithm may lead to qualitatively stronger primitives in quantum cryptography.
format Preprint
id arxiv_https___arxiv_org_abs_2410_03453
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A New World in the Depths of Microcrypt: Separating OWSGs and Quantum Money from QEFID
Behera, Amit
Malavolta, Giulio
Morimae, Tomoyuki
Mour, Tamer
Yamakawa, Takashi
Quantum Physics
Cryptography and Security
While in classical cryptography, one-way functions (OWFs) are widely regarded as the "minimal assumption," the situation in quantum cryptography is less clear. Recent works have put forward two concurrent candidates for the minimal assumption in quantum cryptography: One-way state generators (OWSGs), postulating the existence of a hard search problem with an efficient verification algorithm, and EFI pairs, postulating the existence of a hard distinguishing problem. Two recent papers [Khurana and Tomer STOC'24; Batra and Jain FOCS'24] showed that OWSGs imply EFI pairs, but the reverse direction remained open. In this work, we give strong evidence that the opposite direction does not hold: We show that there is a quantum unitary oracle relative to which EFI pairs exist, but OWSGs do not. In fact, we show a slightly stronger statement that holds also for EFI pairs that output classical bits (QEFID). As a consequence, we separate, via our oracle, QEFID, and one-way puzzles from OWSGs and several other Microcrypt primitives, including efficiently verifiable one-way puzzles and unclonable state generators. In particular, this solves a problem left open in [Chung, Goldin, and Gray Crypto'24]. Using similar techniques, we also establish a fully black-box separation (which is slightly weaker than an oracle separation) between private-key quantum money schemes and QEFID pairs. One conceptual implication of our work is that the existence of an efficient verification algorithm may lead to qualitatively stronger primitives in quantum cryptography.
title A New World in the Depths of Microcrypt: Separating OWSGs and Quantum Money from QEFID
topic Quantum Physics
Cryptography and Security
url https://arxiv.org/abs/2410.03453