Quantum Private Query Protocol Research Articles

Decoy-state quantum private query protocol with two-way communication

Quantum private query (QPQ) is a communication protocol established under the condition of mutual distrust between communication parties, which is used to solve the symmetrically private information retrieval problem in the quantum field. However, most of the existing QPQ protocols are based on the ideal light source. In practice, the multi-photon pulse generated by the transmitter will bring great security problems. We analyze the actual security of QPQ protocol in two-way communication, and find that database security and user privacy will be seriously threatened under multi-photon pulse. So we adopt the decoy state method to solve the actual security problem of QPQ protocol in view of the user side as the light source. The results show that the decoy state method is suitable for QPQ protocol of two-way communication, and can effectively defend against multi-photon pulse attacks.

Security Loophole and Improvement of Quantum Private Query Protocol Based on W State

Security Loophole and Improvement of Quantum Private Query Protocol Based on W State

New flexible quantum private query protocol against rotation noise

The quantum privacy query protocol (QPQ) is faced with low query efficiency, transmission channel noise, and low transmission efficiency problems. The quantum-privacy query protocol proposed by us aims to achieve a better quantum-privacy block query effect and has the function of anti-rotation noise. To solve the collective rotation noise in the transmission channel, we propose a one-way QPQ protocol based on four particles. The four-particle states { $$\left| {\phi_{0} } \right\rangle$$ , $$\left| {\phi_{1} } \right\rangle$$ , $$\left| {\phi_{0} ^{\prime}} \right\rangle$$ , $$\left| {\phi_{1} ^{\prime}} \right\rangle$$ } can be entangled by two Bell states { $$\left| {\Phi^{ + } } \right\rangle ,\left| {\Psi^{ - } } \right\rangle$$ } with anti-noise properties. In general, the unidirectional quantum privacy query has more advantages than a bidirectional quantum privacy query. Besides, the post-processing scheme Yang et al. (Quantum Inf Process 15(9):38333840, 2016) can not only protect the parity result of the random key but also guarantee the security of the protocol. In the security analysis, we prove the security of the user and database.

Two quantum private query protocols based on Bell states and single photons

This paper proposes two quantum privacy query protocols. In the single vector sub-privacy query of protocol 1, it is proposed for the first time to distinguish different measurement results by publishing 2 bits of classic information. In the protocol, the database Bob selects the Z base and the Bell base to measure the particles sent by Alice according to the key value of the encrypted database and publishes 2 bits of classic information based on the measurement results. The user Alice infers the key value of the encrypted database through these two pieces of classic information. In the two-way quantum privacy query of protocol 2, the database Bob measures the particles sent back by Alice, converts the measurement result into a key value of length 3, and prepares a particle that is the same as the measurement result and sends it back to Alice. Alice returns the measurement of particles can infer a set of data encryption keys, and the length of each key is 3 bits. Users in the two protocols proposed in the article can obtain the query key with a probability of 1/4. As the key length increases, the number of query bits in protocol 2 decreases, but the probability of execution failure increases. But protocol 2 has a higher quantum efficiency. Both protocols can guarantee the privacy of users and databases.

Cryptanalysis of Multi-User Quantum Private Query Protocol

Recently, Tian et al. proposed a multi-user quantum private query protocol. The protocol realizes the function of n users querying the database at the same time, which can well protect the privacy of users and databases, and has high efficiency of implementation. Unfortunately, it has security vulnerability in the process of sending quantum sequences. Based on this vulnerability, we propose a man-in-the-middle attack on multi-user quantum private query protocol. Firstly, this paper reviews the multi-user quantum private query protocol. Secondly, the implementation steps of multi-user private query protocol are reviewed concisely. Finally, we pointed that in the protocol, Eve, the eavesdropper, can pretend to be Bob and the identity of the user to obtain the key of query data and steal the database information without being discovered. Through analysis, we find that man in the middle attack is feasible.

Practical Quantum Database Private Query Protocol with Classical Database Owner

Based on single photons, a practical quantum private query protocol is proposed. The powerful user Alice can obtain an item from a limited “classical” database owner Bob using the idea of semi-quantum in the proposed protocol. It does not require that all the participants equipped with expensive quantum resources. Therefore, our protocol is easier to implement under the current technology. Furthermore, the simulate quantum circuit for the proposed protocol is descried in the paper. And security of the proposed schemes has been analyzed. The results show that the protocol can not only resist an external eavesdropping attacks but also protect the database and user owner privacy.

Multi-user quantum private query

Quantum private query (QPQ) is a kind of secure information retrieve protocol, in which both user and database privacy can be protected. Previous QPQ protocols generally consider one user retrieving and need to be performed repeatedly between each user and the database provider when multiple users want to retrieve information from a database. This work focuses on a particular scenario, where multiple users work together to accomplish a task and need to securely query the same item from a database, and proposes a multi-user QPQ protocol using entanglement swapping technology of multi-particle GHZ state. The security analysis shows that the user and database privacy are both guaranteed by real-time security detection.

Multi-User Quantum Private Query Protocol

Recently, Gao et al. suggested a flexible quantum private query (QPQ) protocol (Opt Express, 2012, 20(16):17411) through Jakobi et al.’s quantum-key-distribution based QPQ protocol (Phys Rev A, 2011, 83:022301). Inspired by Gao et al.’s QPQ protocol, we design a multi-user QPQ protocol by using the product states of single-photon states. Its database privacy and user privacy should be compromised by choosing an suitable value for θ. Due to the honesty check process for the database owner, an smaller θ can be priorly chosen to guarantee better database privacy. Moreover, it naturally inherits some good characteristics of Gao et al.’s QPQ protocol so that it is also loss-tolerant, practical to huge-database condition, robust against quantum memory attack and flexible. It differs from Gao et al.’s QPQ protocol on three aspects: firstly, it adds the process of checking the presence of an illegal eavesdropper; secondly, it adds the process of checking the database owner’s honesty; and finally, it is feasible for n users to query the items of database simultaneously.

Development of Quantum Private Queries Protocol on Collective-Dephasing Noise Channel

Quantum private queries can commonly protect important information in a good many of domains, such as finance, business, military, which use quantum effects to achieve unprecedented classical private queries. However, quantum state can be easily affected by environmental noise, which affects the actual effect of quantum private queries. This paper developed a new quantum private query protocol based on four qubits logical Bell state to resist the collective-dephasing noise. The symmetric private information retrieval problem, which is the most influential problem in the process of quantum private query, was solved well by quantum oblivious transfer. It introduces the construction of four qubits logical Bell state. The quantum private query protocol innovates the quantum key distribution process by using the four qubits logical Bell state as the measurement base to measure the logical qubits, and ensures the function of quantum oblivious transmission. The protocol cannot only resist the noise influence of the communication process, but also ensure the security of both sides of the communication.

Error Tolerance Bound in QKD-Based Quantum Private Query

Most existing quantum private query (QPQ) protocols can hardly work in the presence of noise. The user Alice may obtain a false database item in noisy environments and both participants may cheat under the disguise of noise, so dealing with the noise needs an overall consideration of error correction, user privacy and database security. However, the only two existing protocols aiming to correct errors in QPQ lack such an overall consideration (at least one party’s privacy can be revealed), and they did not estimate what extent of errors can be tolerated (actually, noise is seldom discussed in quantum two-party secure computations, and to the best of our knowledge, relevant bounds on tolerable errors remain unattainable so far). To solve this problem, we first exemplify how one participant reveals the other party’s privacy in the existing QPQ protocols aiming to correct errors. Then we propose a practical protocol which can really work via noisy channel, that is, the error rate of the retrieved database item is reduced significantly and both parties’ privacy are well protected. Besides, we deduce that the final error rate, user privacy and database security are pairwise in a “trade-off” relationship. By balancing them according to the required level of security and reliability, we obtain an upper bound on tolerable errors.

Secure Multi-Party Quantum Private Information Query

Different from the existing quantum key distribution (QKD)-based quantum private query (QPQ) protocols, we propose a secure multi-party quantum private information query protocol utilizing universal blind quantum computation in quantum cloud computing. Due to the blindness and correctness of blind quantum computation, our protocol guarantees the privacy and security for all the clients and the servers. The clients obtain values corresponding to their queries only, and nothing else from the servers, while the servers can not get any information about the queries. In our protocols, the only thing that the clients do is to need the ability to perform single-qubit measurement or to prepare single-qubit states.

Security improvements of several basic quantum private query protocols with O(log N) communication complexity

New quantum private database (with N elements) query protocols are presented and analyzed. Protocols preserve O(log⁡N) communication complexity of known protocols for the same task, but achieve several significant improvements in security, especially concerning user privacy. For example, the randomized form of our protocol has a cheat-sensitive property – it allows the user to detect a dishonest database with a nonzero probability, while the phase-encoded private query protocols [6,7] for the same task do not have such a property. Moreover, when the database performs the computational basis measurement, a particular projective measurement which can cause a significant loss of user privacy in the previous private query protocols with O(log⁡N) communication complexity, at most half of the user privacy could leak to such a database in our protocol, while in the QPQ protocol [5], the entire user privacy could leak out. In addition, it is proved here that for large N, the user could detect a cheating via the computational basis measurement, with a probability close to 12 using O(N) special queries. Finally, it is shown here, for both forms of our protocol, basic and randomized, how a dishonest database has to act in case it could not learn user's queries.

Quantum Private Query Based on Stable Error Correcting Code in the Case of Noise

In order to protect the privacy of query users and databases, a quantum private query protocol under noisy conditions is proposed and studied. It is a one-way quantum protocol that not only protects user privacy, but also prevents eavesdropping. And in the protocol initialization phase, the identity is verified by the quantum entanglement pair. Through key distribution, a user only knows a part of the key, and the accuracy of the original key needs to be considered. Channel noise directly affects the transmission result of quantum bits and reduces the transmission accuracy. In addition, the presence of eavesdropper Eve may also affect the transmission of qubits. The receiver corrects the error by using quantum error correction technology, thereby improving the efficiency of protocol communication.

Practical quantum private query based on Bell state

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.

An efficient Quantum Private Query Protocol Based on Oracle and Grover Iteration

Private query allows a client, Alice, to retrieve an item of a database hold by the server, Bob, without revealing which item he or she retrieved, while limiting his ability to access other items. In this paper, an efficient quantum private query (QPQ) protocol is proposed, where two oracle operations Ok, Od are utilized to encode the encryption keys and the encrypted data items into their corresponding quantum superposition states $\left | {\phi ^{\prime }} \right \rangle $ , $\left | {\psi ^{\prime }} \right \rangle $ , and the Grover iteration is also introduced to extract the target state $\left | {{d_{i}}^{\prime }} \right \rangle $ (i.e., the state of the encrypted data item Alice retrieved) from the superposition state. In order to guarantee the client’s privacy, the server Bob transmits all the encrypted data items of the database to the client Alice with oblivious transfer strategy. Compared with the previous qRAM-based or QKD-based QPQ protocols, our communication complexity (i.e., the number of transmitted qubits) is reduced from O(NlogN) or O(N) to O(logN), and the exchanged classical message is reduced from O(N) bits to O(logN) bits too. The security analysis shows our protocol can not only guarantee the server’s privacy but also the client’s privacy.

A New Protocol for Quantum Private Query Against Joint-Measurement Attack

The quantum-key-distribution (QKD)-based quantum private query (QPQ) has become a research hotspot in recent years. Although such QPQ protocols are practical, joint-measurement (JM) attack is a noteworthy threat to the security of the database. In this paper, we propose a new QPQ protocol for enhancing database security against JM attack. The special procedure “receive→measure→re-prepare→send” for the user Alice prevents her from saving states to perform JM attack. Furthermore, since each photon only travels from one party to the other, our protocol reduces the drawback of two-way communication so that the transmission distance between Alice and the database holder Bob is satisfactory. We also analyze the security of the proposed protocol in terms of the database privacy and user privacy. Moreover, our protocol preserves the excellent character of QKD-based QPQs that it is loss tolerant.

Practical Quantum Private Query with Classical Participants**Supported by the National Key R&D Program of China under Grant No 2017YFB0802300, and the Foundation Science and Forefront Technology of Chongqing Science and Technology Commission of China under Grant No cstc2016jcyjA0571.

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.

How Bob in Quantum Private Query Protocol Gets the Element?

Quantum private query (QPQ) requires that the database holder Bob knows nothing about his client Alice, including the index she provides and the element she obtains. However, on some occasion, Bob wants to know which element he has revealed to Alice. Therefore, we raise a symmetric quantum private query (SQPQ) problem in this paper. SQPQ can guarantee that Alice shares the real element with Bob and also partially protect the privacy of Alice's index. Some necessary conditions are need to satisfy to implement SQPQ. We prove that Alice must provide some extra information to enable Bob to know the element. Then, we define the term “absolutely secure”, which is a security notion stronger than cheat sensitive, and prove that “absolutely secure”SQPQ is impossible. In addition, we raise a cheat sensitive scheme three-databases-detection to implement SQPQ protocol. Finally, we construct a reduction from SQPQ to quantum bit commitment (QBC) to clarify that SQPQ is a problem more difficult than QBC.

QKD-Based Quantum Private Query Protocol in the Single-Photon Interference Communication System

In this paper, we propose a quantum-key-distribution-based quantum private query protocol (QKD-based QPQ) utilizing the uncertainty relation of the photon path and the interference result in the single-photon interference circuit. The proposed protocol is loss-tolerant and easy to be realized in the quantum communication systems based on single-photon interference. Without any assumption on the dishonest party's computation ability, we prove that the dishonest user can only steal a little more than one item from the database, and any dishonest action of the database would be found by the user with a nonzero probability. Compared with other QKD-based QPQ protocols utilizing single-photon interference, the proposed protocol uses less quantum devices, which means the costs of the proposed protocol is lower.

Quantum Private Query With Perfect Performance Universally Applicable Against Collective-Noise

Almost all of the previous quantum private query (QPQ) protocols are always based on an ideal environment without any noise. Nevertheless, due to the defects of the channel, channel noise inevitably exists in the actual transmission process, which will give rise to transmission error and reduce the probability of successful quantum transmission. An eavesdropper may disguise her actions as channel noise to avoid being detected by legitimate parties during security checks. To solve this problem, we present a QPQ protocol with perfect performance universally applicable against collective noise. Concretely, the protocol encodes bits in noiseless subspace and thus can function over a quantum channel subjected to an arbitrary degree of collective noise, as occurs, for instance, due to polarization rotation in an optical fiber. Furthermore, Bob cannot get the information about Alice’s choice at all by taking fake entangled attack and by taking fake photon attack, the probability Bob can get the information about Alice’s choice is only approximately 6.7%, which is far less than the probability of 25% in Yang et al. ’s protocol. Moreover, the conclusiveness of the user Alice’s measurement results is subject to quantum randomness rather than allowing Alice to choose by herself to obtain a conclusive result in Wei et al. ’s protocol, which prevents Alice’s intuitive attack and meanwhile makes it arduous for Bob to perform the joint-measurement attack. Our protocol uses only one state, which reduces the communication complexity, and is, therefore, an effective QPQ solution with the high-security level.