International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 01 April 2024

Cezary Pilaszewicz, Lea R. Muth, Marian Margraf
ePrint Report ePrint Report
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.

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