Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Communications in Theoretical Physics

A Quantum Private Query Protocol for Enhancing both User and Database Privacy*

Yi‐Hua Zhou, Xuewei Bai, Lei-Lei Li, Wei‐Min Shi, Yu‐Guang Yang

Published Jan 1, 2018• 8 citations
Publisher

Abstract

Abstract In order to protect the privacy of query user and database, some QKD-based quantum private query (QPQ) protocols were proposed. Unfortunately some of them cannot resist internal attack from database perfectly; some others can ensure better user privacy but require a reduction of database privacy. In this paper, a novel two-way QPQ protocol is proposed to ensure the privacy of both sides of communication. In our protocol, user makes initial quantum states and derives the key bit by comparing initial quantum state and outcome state returned from database by ctrl or shift mode instead of announcing two non-orthogonal qubits as others which may leak part secret information. In this way, not only the privacy of database be ensured but also user privacy is strengthened. Furthermore, our protocol can also realize the security of loss-tolerance, cheat-sensitive, and resisting JM attack etc.

DOI
10.1088/0253-6102/69/1/31

Related papers

Cryptanalysis and improvement to the quantum private query protocol for enhancing database privacy

Zhengda Shen, Wenzhu Shao, Zhigang Li +4 more

Abstract In order to protect the privacy of the query user and database, some QKD-based quantum private query (QPQ) protocols were proposed. One example is the protocol proposed by Zhou et al, in which the user makes initial quantum states and derives the key bit by comparing the initial quantum state and the outcome state returned from the database by ctrl or shift mode, instead of announcing two non-orthogonal qubits as others which may leak part secret information. To some extent, the security of the database and the privacy of the user are strengthened. Unfortunately, we find that in this protocol, the dishonest user could be obtained, utilizing unambiguous state discrimination, much more database information than that is analyzed in Zhou et al’s original research. To strengthen the database security, we improved the mentioned protocol by modifying the information returned by the database in various ways. The analysis indicates that the security of the improved protocols is greatly enhanced.

Communications in Theoretical Physics•Nov 26, 2024•0 citations

Practical quantum private query with better performance in resisting joint-measurement attack

Chun‐Yan Wei, Tian‐Yin Wang, Fei Gao

As a kind of practical protocol, quantum-key-distribution (QKD)-based quantum private queries (QPQs) have drawn lots of attention. However, joint-measurement (JM) attack poses a noticeable threat to the database security in such protocols. That is, by JM attack a malicious user can illegally elicit many more items from the database than the average amount an honest one can obtain. Taking Jacobi et al.'s protocol as an example, by JM attack a malicious user can obtain as many as 500 bits, instead of the expected 2.44 bits, from a ${10}^{4}$-bit database in one query. It is a noticeable security flaw in theory, and would also arise in application with the development of quantum memories. To solve this problem, we propose a QPQ protocol based on a two-way QKD scheme, which behaves much better in resisting JM attack. Concretely, the user Alice cannot get more database items by conducting JM attack on the qubits because she has to send them back to Bob (the database holder) before knowing which of them should be jointly measured. Furthermore, JM attack by both Alice and Bob would be detected with certain probability, which is quite different from previous protocols. Moreover, our protocol retains the good characters of QKD-based QPQs, e.g., it is loss tolerant and robust against quantum memory attack.

Physical Review A•Apr 12, 2016•140 citations

Practical quantum private query based on Bell state

Tao Zheng, Shibin Zhang, Xiang Gao +1 more

Quantum private query (QPQ) is a cryptographic application that protects the privacy of both users and databases while querying the database secretly. In most existing QPQ protocols, the protection of user privacy can only be cheat-sensitive. Cheat-sensitive means that Bob will be found later with a certain probability if he tries to get the address queried by Alice. On the premise of cheat-sensitivity, although Alice can discover Bob’s malicious behavior after a query (transaction), the secret information of Alice was leaked in the completed query, which is likely to be a fatal blow to Alice. Or, to prevent Bob’s malicious behavior, Alice executes one or more additional queries to test Bob’s honesty. However, to bypass Alice’s honesty test, Bob can also provide several honest queries before performing dishonest queries. Therefore, cheat-sensitive should not be the ultimate goal of user privacy protection in QPQ. In this paper, we propose a practical QKD-based QPQ protocol with better user privacy protection than cheat-sensitivity based on order rearrangement of qubits. The proposed QPQ protocol can resist the Trojan horse attack even without wavelength filter and photon number splitter (PNS) equipped with auxiliary monitoring detectors.

Modern Physics Letters A•Jun 14, 2019•15 citations

Practical Quantum Private Query with Classical Participants

Min Xiao, Di-Fang Zhang

Quantum key distribution (QKD)-based quantum private query (QPQ) is a practical application of QKD, which relaxes the security condition of perfectly concealing a private query to a cheating-sensitive strategy. We propose a QPQ protocol based on the delegated QKD scheme (DQKD-based QPQ), in which two almost 'classical' clients (data user and database owner) can establish a 1-out-of-N oblivious key with the help of a cloud server with full quantum ability. Concretely, the two classical participants in the DQKD-based QPQ only need to access the quantum channel and reorder qubits, and the costly quantum operations, quantum state preparation and measurement are outsourced to a full quantum server in the cloud without leaking participants' privacy. The proposed protocol not only provides a cloud-based framework of QKD-based QPQ, but also obtains better security by a real-time security check, which can protect the security of the database and user against all potential attacks even if the quantum server is assumed to be a powerfully untrusted adversary .

Chinese Physics Letters•Mar 1, 2019•5 citations

Reexamination of the realtime protection for user privacy in practical quantum private query

Chun‐Yan Wei, Xiao‐Qiu Cai, Tian‐Yin Wang

Abstract Quantum private query (QPQ) is the quantum version for symmetrically private information retrieval. However, the user privacy in QPQ is generally guarded in the delayed and cheat-sensitive way. That is, the dishonest database holder Bob’s cheating to elicit user privacy can only be discovered after the protocol is finished (when the user finds some errors in the retrieved database item). Such delayed detection may cause very unpleasant results for the user Alice in real-life applications. Without the realtime conscious of privacy leaking, Alice may make faulty decisions according to the received faulty item and suffer great loss. Worse yet, it is difficult for Alice to accuse a dishonest database to any one else though she can detect the cheating. Current efforts to protect user privacy in realtime in existing QPQ protocols mainly use two techniques, i.e. adding an honesty checking on the database or allowing the user to reorder the qubits. We reexamine these two kinds of QPQ protocols and find neither of them can work very well. We give concrete cheating strategies for both participants and show that honesty checking of inner participant should be dealt more carefully in for example the choosing of checking qubits. Finally, we give an idea to realize realtime detection of dishonest database in QPQ of blocks (i.e. multi-bit database items).

arXiv:2407.19147•Physica Scripta•Nov 18, 2024•1 citation

A novel quantum private query protocol and its application in private set intersection

Zeping Deng, Hongwei Sun, Kejia Zhang +3 more

As an important topic in quantum secure multiparty computing, quantum privacy query (QPQ) can solve the problem of information query between users and database owners without compromising privacy. In the existing research, most of them focus on its functions, not its applications. In this paper, a new QPQ protocol based on two-particle states is proposed. In our protocol, we use two-particle states combined with the Ctrl or Shift operations to give the user a partial key sequence and the database cannot recognize the user's key sequence. Meanwhile, we conduct simulation experiments at the IBM quantum experience and show that it is feasible. We discuss its application in the private set intersection (PSI), which is derived from QPQ. According to our analysis, the QPQ protocol and PSI protocol are secure.

Scientific Reports•Oct 14, 2025•2 citations
Abstract In order to protect the privacy of query user and database, some QKD-based quantum private query (QPQ) protocols were proposed. Unfortunately some of them cannot resist internal attack from database perfectly; some others can ensure better user privacy but require a reduction of database privacy. In this paper, a novel two-way QPQ protocol is proposed to ensure the privacy of both sides of communication. In our protocol, user makes initial quantum states and derives the key bit by comparing initial quantum state and outcome state returned from database by ctrl or shift mode instead of announcing two non-orthogonal qubits as others which may leak part secret information. In this way, not only the privacy of database be ensured but also user privacy is strengthened. Furthermore, our protocol can also realize the security of loss-tolerance, cheat-sensitive, and resisting JM attack etc.
Abstract In order to protect the privacy of the query user and database, some QKD-based quantum private query (QPQ) protocols were proposed. One example is the protocol proposed by Zhou et al, in which the user makes initial quantum states and derives the key bit by comparing the initial quantum state and the outcome state returned from the database by ctrl or shift mode, instead of announcing two non-orthogonal qubits as others which may leak part secret information. To some extent, the security of the database and the privacy of the user are strengthened. Unfortunately, we find that in this protocol, the dishonest user could be obtained, utilizing unambiguous state discrimination, much more database information than that is analyzed in Zhou et al’s original research. To strengthen the database security, we improved the mentioned protocol by modifying the information returned by the database in various ways. The analysis indicates that the security of the improved protocols is greatly enhanced.
As a kind of practical protocol, quantum-key-distribution (QKD)-based quantum private queries (QPQs) have drawn lots of attention. However, joint-measurement (JM) attack poses a noticeable threat to the database security in such protocols. That is, by JM attack a malicious user can illegally elicit many more items from the database than the average amount an honest one can obtain. Taking Jacobi et al.'s protocol as an example, by JM attack a malicious user can obtain as many as 500 bits, instead of the expected 2.44 bits, from a 104{10}^{4}104-bit database in one query. It is a noticeable security flaw in theory, and would also arise in application with the development of quantum memories. To solve this problem, we propose a QPQ protocol based on a two-way QKD scheme, which behaves much better in resisting JM attack. Concretely, the user Alice cannot get more database items by conducting JM attack on the qubits because she has to send them back to Bob (the database holder) before knowing which of them should be jointly measured. Furthermore, JM attack by both Alice and Bob would be detected with certain probability, which is quite different from previous protocols. Moreover, our protocol retains the good characters of QKD-based QPQs, e.g., it is loss tolerant and robust against quantum memory attack.
Quantum private query (QPQ) is a cryptographic application that protects the privacy of both users and databases while querying the database secretly. In most existing QPQ protocols, the protection of user privacy can only be cheat-sensitive. Cheat-sensitive means that Bob will be found later with a certain probability if he tries to get the address queried by Alice. On the premise of cheat-sensitivity, although Alice can discover Bob’s malicious behavior after a query (transaction), the secret information of Alice was leaked in the completed query, which is likely to be a fatal blow to Alice. Or, to prevent Bob’s malicious behavior, Alice executes one or more additional queries to test Bob’s honesty. However, to bypass Alice’s honesty test, Bob can also provide several honest queries before performing dishonest queries. Therefore, cheat-sensitive should not be the ultimate goal of user privacy protection in QPQ. In this paper, we propose a practical QKD-based QPQ protocol with better user privacy protection than cheat-sensitivity based on order rearrangement of qubits. The proposed QPQ protocol can resist the Trojan horse attack even without wavelength filter and photon number splitter (PNS) equipped with auxiliary monitoring detectors.
Quantum key distribution (QKD)-based quantum private query (QPQ) is a practical application of QKD, which relaxes the security condition of perfectly concealing a private query to a cheating-sensitive strategy. We propose a QPQ protocol based on the delegated QKD scheme (DQKD-based QPQ), in which two almost 'classical' clients (data user and database owner) can establish a 1-out-of-N oblivious key with the help of a cloud server with full quantum ability. Concretely, the two classical participants in the DQKD-based QPQ only need to access the quantum channel and reorder qubits, and the costly quantum operations, quantum state preparation and measurement are outsourced to a full quantum server in the cloud without leaking participants' privacy. The proposed protocol not only provides a cloud-based framework of QKD-based QPQ, but also obtains better security by a real-time security check, which can protect the security of the database and user against all potential attacks even if the quantum server is assumed to be a powerfully untrusted adversary .
Abstract Quantum private query (QPQ) is the quantum version for symmetrically private information retrieval. However, the user privacy in QPQ is generally guarded in the delayed and cheat-sensitive way. That is, the dishonest database holder Bob’s cheating to elicit user privacy can only be discovered after the protocol is finished (when the user finds some errors in the retrieved database item). Such delayed detection may cause very unpleasant results for the user Alice in real-life applications. Without the realtime conscious of privacy leaking, Alice may make faulty decisions according to the received faulty item and suffer great loss. Worse yet, it is difficult for Alice to accuse a dishonest database to any one else though she can detect the cheating. Current efforts to protect user privacy in realtime in existing QPQ protocols mainly use two techniques, i.e. adding an honesty checking on the database or allowing the user to reorder the qubits. We reexamine these two kinds of QPQ protocols and find neither of them can work very well. We give concrete cheating strategies for both participants and show that honesty checking of inner participant should be dealt more carefully in for example the choosing of checking qubits. Finally, we give an idea to realize realtime detection of dishonest database in QPQ of blocks (i.e. multi-bit database items).
As an important topic in quantum secure multiparty computing, quantum privacy query (QPQ) can solve the problem of information query between users and database owners without compromising privacy. In the existing research, most of them focus on its functions, not its applications. In this paper, a new QPQ protocol based on two-particle states is proposed. In our protocol, we use two-particle states combined with the Ctrl or Shift operations to give the user a partial key sequence and the database cannot recognize the user's key sequence. Meanwhile, we conduct simulation experiments at the IBM quantum experience and show that it is feasible. We discuss its application in the private set intersection (PSI), which is derived from QPQ. According to our analysis, the QPQ protocol and PSI protocol are secure.