Semi-Quantum Copy-Protection and More

Céline Chevalier; Paul Hermouet; Quoc-Huy Vu

Paper 2023/244

Semi-Quantum Copy-Protection and More

Céline Chevalier, CRED, Université Panthéon-Assas, Paris II, France, DIENS, École normale supérieure, PSL University, CNRS, INRIA, Paris, France

Paul Hermouet, CRED, Université Panthéon-Assas, Paris II, France, DIENS, École normale supérieure, PSL University, CNRS, INRIA, Paris, France

Quoc-Huy Vu, LIP6, Sorbonne Université, Paris, France

Abstract

Properties of quantum mechanics have enabled the emergence of quantum cryptographic protocols achieving important goals which are proven to be impossible classically. Unfortunately, this usually comes at the cost of needing quantum power from every party in the protocol, while arguably a more realistic scenario would be a network of classical clients, classically interacting with a quantum server. In this paper, we focus on copy-protection, which is a quantum primitive that allows a program to be evaluated, but not copied, and has shown interest especially due to its links to other unclonable cryptographic primitives. Our main contribution is to show how to dequantize existing quantum copy-protection from hidden coset states, by giving a construction for classically-instructed remote state preparation for coset states. We then apply this dequantizer to obtain semi-quantum cryptographic protocols for copy-protection and tokenized signatures with strong unforgeability. In the process, we present the first secure copy-protection scheme for point functions in the plain model and a new direct product hardness property of coset states which immediately implies a strongly unforgeable tokenized signature scheme.

Note: Full version

Metadata

Available format(s): PDF
Category: Foundations
Publication info: A major revision of an IACR publication in TCC 2023
Keywords: quantum cryptography unclonable cryptography copy-protection remote state preparation
Contact author(s): celine chevalier @ ens fr
paul hermouet @ ens fr
quoc huy vu @ ens fr
History: 2023-09-19: last of 4 revisions; 2023-02-21: received; See all versions
Short URL: https://ia.cr/2023/244
License: CC BY

BibTeX

@misc{cryptoeprint:2023/244,
      author = {Céline Chevalier and Paul Hermouet and Quoc-Huy Vu},
      title = {Semi-Quantum Copy-Protection and More},
      howpublished = {Cryptology ePrint Archive, Paper 2023/244},
      year = {2023},
      note = {\url{https://eprint.iacr.org/2023/244}},
      url = {https://eprint.iacr.org/2023/244}
}