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Mathematics

Device Independent Quantum Private Queries Based on Quantum Key Distribution

Li Liu, Qingshan Du, Xu Kuo Gao

Published Mar 13, 2025• 1 citation
Publisher

Abstract

Symmetric private information retrieval (SPIR) protocol is proposed for users to retrieve items from a database holder without revealing the retrieval address, and meanwhile the users cannot learn any additional entries of the database. Quantum key distribution (QKD)-based quantum private queries (QPQs) are the most practical protocols for the SPIR problem. However, most existing protocols assume ideal devices. To overcome this drawback, we propose a device independent QPQ protocol based on QKD with imperfect sources and detectors. By constructing the semi-definite programming optimization problem, we give the CHSH test threshold and prove the correctness of our protocol. We use the shift and permutation post-processing technique to further improve the security. We compare the performance of our protocol with a recent full device-independent QPQ. and discuss their relative advantages. The simulation results show that our protocol improves database security, user privacy and efficiency. The number of final key bits that Alice knows is close to 1, and Bob’s guessing probability is below 0.15 in our protocol. Moreover, the proposed scheme can be used for any entanglement-based QPQ protocol to remove trust on the devices.

DOI
10.3390/math13060951

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Symmetric private information retrieval (SPIR) protocol is proposed for users to retrieve items from a database holder without revealing the retrieval address, and meanwhile the users cannot learn any additional entries of the database. Quantum key distribution (QKD)-based quantum private queries (QPQs) are the most practical protocols for the SPIR problem. However, most existing protocols assume ideal devices. To overcome this drawback, we propose a device independent QPQ protocol based on QKD with imperfect sources and detectors. By constructing the semi-definite programming optimization problem, we give the CHSH test threshold and prove the correctness of our protocol. We use the shift and permutation post-processing technique to further improve the security. We compare the performance of our protocol with a recent full device-independent QPQ. and discuss their relative advantages. The simulation results show that our protocol improves database security, user privacy and efficiency. The number of final key bits that Alice knows is close to 1, and Bob’s guessing probability is below 0.15 in our protocol. Moreover, the proposed scheme can be used for any entanglement-based QPQ protocol to remove trust on the devices.
Quantum Private Query (QPQ) is an unconditional secure mistrustful cryptographic primitive which is assumed to be a probabilistic version of the Oblivious Transfer (OT) schemes or an imperfect version of Symmetric Private Information Retrieval (SPIR) schemes. Recently, Maitra et al. (Phys. Rev. A, 2017) identified that the B92 QKD-based QPQ scheme proposed by Yang et al. (Quant. Inf. Process., 2014) is vulnerable whenever the devices involved in that scheme are dubious and to improve the overall security, they suggested a semi-Device Independent (DI) proposal for that QPQ scheme by introducing a local test at the server's end. In this work, we overcome the limitation of the Maitra et al. proposal by removing trustworthiness from all the (involved) devices, and suggest a full DI proposal for the Yang et al. scheme, exploiting a proper self-testing mechanism of observables along with the local version of the tilted CHSH game. We compare the performance of our proposal with a recent full DI-QPQ scheme (arxiv 1901.03042) and discuss their relative advantages. Additionally, we present a DI proposal for a modified version of the Yang et al. scheme, enabling the client to retrieve maximum raw key bits during the oblivious key generation phase. We evaluate the security of all our proposals with a formal analysis.
Private information retrieval (PIR) is a database query protocol that provides user privacy in that the user can learn a particular entry of the database of his interest but his query would be hidden from the data centre. Symmetric private information retrieval (SPIR) takes PIR further by additionally offering database privacy, where the user cannot learn any additional entries of the database. Unconditionally secure SPIR solutions with multiple databases are known classically, but are unrealistic because they require long shared secret keys between the parties for secure communication and shared randomness in the protocol. Here, we propose using quantum key distribution (QKD) instead for a practical implementation, which can realise both the secure communication and shared randomness requirements. We prove that QKD maintains the security of the SPIR protocol and that it is also secure against any external eavesdropper. We also show how such a classical-quantum system could be implemented practically, using the example of a two-database SPIR protocol with keys generated by measurement device-independent QKD. Through key rate calculations, we show that such an implementation is feasible at the metropolitan level with current QKD technology.
Quantum private queries (QPQ) is an important cryptography protocol aiming to protect both the user's and database's privacy when the database is queried privately. Recently, a variety of practical QPQ protocols based on quantum key distribution (QKD) have been proposed. However, for QKD-based QPQ the user's imperfect detectors can be subjected to some detector- side-channel attacks launched by the dishonest owner of the database. Here, we present a simple example that shows how the detector-blinding attack can damage the security of QKD-based QPQ completely. To remove all the known and unknown detector side channels, we propose a solution of measurement-device-independent QPQ (MDI-QPQ) with single- photon sources. The security of the proposed protocol has been analyzed under some typical attacks. Moreover, we prove that its security is completely loss independent. The results show that practical QPQ will remain the same degree of privacy as before even with seriously uncharacterized detectors.
Secure information retrieval is an essential task in today's highly digitised society. In some applications, it may be necessary that user query's privacy and database content's security are enforced. For these settings, symmetric private information retrieval (SPIR) could be employed, but its implementation is known to be demanding, requiring a private key-exchange network as the base layer. Here, we report for the first time a realisation of provably-secure SPIR supported by a quantum-secure key-exchange network. The SPIR scheme looks at biometric security, offering secure retrieval of 582-byte fingerprint files from a database with 800 entries. Our experimental results clearly demonstrate the feasibility of SPIR with quantum secure communications, thereby opening up new possibilities in secure distributed data storage and cloud computing over the future Quantum Internet.
Quantum Private Query (QPQ) based on Quantum Key Distribution (QKD) is among the most practically viable quantum communication protocols, with application value second only to QKD itself. However, prevalent security vulnerabilities in the post-processing stages of most existing QKD-based QPQ protocols have been severely overlooked. This study focuses on hidden information extraction under undetermined signal bits, revealing that most such QPQ protocols face severe security threats even without complex quantum resources. Specifically, direct observation attack causes incremental information leakage, while the minimum error discrimination attack efficiently steals additional database inforamtion. To address these critical flaws, the proposed multi-encryption defense scheme is compatible with existing QPQ protocols. The study demonstrates the necessity of the multi-encryption strategy for the security of databases in QPQ, providing key theoretical and technical support for constructing practical QPQ protocols resistant to real-world attacks.
Secure information retrieval is an essential task in today's highly digitised society. In some applications, it may be necessary that user query's privacy and database content's security are enforced. For these settings, symmetric private information retrieval (SPIR) could be employed, but its implementation is known to be demanding, requiring a private key-exchange network as the base layer. Here, we report for the first time a realisation of provably-secure SPIR supported by a quantum-secure key-exchange network. The SPIR scheme looks at biometric security, offering secure retrieval of 582-byte fingerprint files from a database with 800 entries. Our experimental results clearly demonstrate the feasibility of SPIR with quantum secure communications, thereby opening up new possibilities in secure distributed data storage and cloud computing over the future Quantum Internet.