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

2026-04-11

AI Summary

Although quantum encryption-based cloning protocols adhere to the no-cloning theorem, their redundant storage design may introduce information leakage risks. This work provides the first systematic characterization of the structural properties of such leakage by employing quantum information theory and subset classification techniques. The storage registers are rigorously partitioned into three categories: authorized, informationless, and partially informative. The study analyzes the residual dependence of unauthorized subsets on the input state and reveals that leakage patterns are closely tied to the parity of the register size. It establishes precise conditions under which partially informative subsets exist and demonstrates that unauthorized subsets can retain limited information about the input, thereby exposing an inherent limitation in the protocol’s confidentiality guarantees.

Technology Category

• Machine Learning: Quantum Machine Learning
• Game Theory and Economic Paradigms: Imperfect Information
• Reasoning under Uncertainty: Uncertainty Representations

Application Category

• Security and Privacy: Data transparency and provenance
• Responsible Web: Measurement, analysis, and circumvention of Web censorship
• Graph Algorithms and Modeling for the Web: Representation, reconstruction, and subgraph or motif discovery in Web-related graphs

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.

Problem

• encrypted cloning
• quantum information leakage
• no-cloning theorem
• confidentiality
• quantum encryption

Innovation

• Quantum Encrypted Cloning
• Information Leakage
• No-Cloning Theorem
• Parity-Dependent Security
• Authorized Subsets