A Black-box Attack on Fixed-Unitary Quantum Encryption Schemes

Cezary Pilaszewicz; Lea R. Muth; Marian Margraf

Paper 2024/511

A Black-box Attack on Fixed-Unitary Quantum Encryption Schemes

Cezary Pilaszewicz

, Freie Universität Berlin

Lea R. Muth, Freie Universität Berlin

Marian Margraf, Freie Universität Berlin

Abstract

We show how fixed-unitary quantum encryption schemes can be attacked in a black-box setting. We use an efficient technique to invert a unitary transformation on a quantum computer to retrieve an encrypted secret quantum state $\ket{\psi}$. This attack has a success rate of 100% and can be executed in constant time. We name a vulnerable scheme and suggest how to improve it to invalidate this attack. The proposed attack highlights the importance of carefully designing quantum encryption schemes to ensure their security against quantum adversaries, even in a black-box setting.

Metadata

Available format(s): PDF
Category: Attacks and cryptanalysis
Publication info: Preprint.
Keywords: quantum cryptography black-box attack quantum cryptanalysis quantum circuits
Contact author(s): cezary pilaszewicz @ gmail com
lea muth @ fu-berlin de
marian margraf @ fu-berlin de
History: 2024-04-01: approved; 2024-03-31: received; See all versions
Short URL: https://ia.cr/2024/511
License: CC0

BibTeX

@misc{cryptoeprint:2024/511,
      author = {Cezary Pilaszewicz and Lea R. Muth and Marian Margraf},
      title = {A Black-box Attack on Fixed-Unitary Quantum Encryption Schemes},
      howpublished = {Cryptology ePrint Archive, Paper 2024/511},
      year = {2024},
      note = {\url{https://eprint.iacr.org/2024/511}},
      url = {https://eprint.iacr.org/2024/511}
}