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arXiv · 2604.10155

Encrypted clones can leak: Classification of informative subsets in Quantum Encrypted Cloning

Gabriele Gianini·Omar Hasan·Corrado Mio·Stelvio Cimato·Ernesto Damiani
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Abstract

Encrypted cloning enables the redundant storage of an unknown qubit while remaining compatible with the no-cloning theorem, since only one clone can later be recovered through key-consuming decryption. Because encryption in this protocol is introduced to enable cloning-compatible redundancy rather than to guarantee confidentiality by design, its secrecy properties must be assessed explicitly. Here we classify the subsets of the encrypted-clone storage register into authorized, completely non-informative, and partially informative sets. We show that intermediate non-authorized subsets may retain only a restricted residual dependence on the input state, and we characterize exactly when this dependence occurs. The resulting leakage pattern is parity-dependent, revealing a structural confidentiality limitation of encrypted cloning.

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Gabriele Gianini, Omar Hasan, Corrado Mio, Stelvio Cimato, Ernesto Damiani. 2026-04-11. Encrypted clones can leak: Classification of informative subsets in Quantum Encrypted Cloning. https://arxiv.org/abs/2604.10155

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