International Association for Cryptologic Research

International Association
for Cryptologic Research


On the (Im)plausibility of Public-Key Quantum Money from Collision-Resistant Hash Functions

Prabhanjan Ananth , UCSB, Santa Barbara, USA
Zihan Hu , Tsinghua University, Beijing, China
Henry Yuen , Columbia University, New York, USA
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Presentation: Slides
Conference: ASIACRYPT 2023
Abstract: Public-key quantum money is a cryptographic proposal for using highly entangled quantum states as currency that is publicly verifiable yet resistant to counterfeiting due to the laws of physics. Despite significant interest, constructing provably-secure public-key quantum money schemes based on standard cryptographic assumptions has remained an elusive goal. Even proposing plausibly-secure candidate schemes has been a challenge. These difficulties call for a deeper and systematic study of the structure of public-key quantum money schemes and the assumptions they can be based on. Motivated by this, we present the first black-box separation of quantum money and cryptographic primitives. Specifically, we show that collision-resistant hash functions cannot be used as a black-box to construct public-key quantum money schemes where the banknote verification makes classical queries to the hash function. Our result involves a novel combination of state synthesis techniques from quantum complexity theory and simulation techniques, including Zhandry's compressed oracle technique.
  title={On the (Im)plausibility of Public-Key Quantum Money from Collision-Resistant Hash Functions},
  author={Prabhanjan Ananth and Zihan Hu and Henry Yuen},