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A boolean QPQ using single photons

Martijn A. Nagtegaal

Published Jun 26, 2015• 0 citations
OpenAlex

Abstract

I propose an implementation of the quantum private query protocol as described in an article using a photon to encode a question and reflectionor transmission of the photon as answer options. Each question is represented by a photon in a transmission line with both ends returning to the user, and the answer is represented by reflection or transmission of this photon caused by the single photon transistor as described in another article. By solving the quantum Langevin equations for the 32 × 32-dimensional operators describing the single photon transistor the system is analysed. This analysis shows that the user privacy is maintained when the returning transmission lines are under the user's control. The probabilities for reflection and transmission are calculated to verify the behaviour of the answering mechanism. By using pulse trains instead of numbered lines to represent questions, the scalability of the system could be improved.

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I propose an implementation of the quantum private query protocol as described in an article using a photon to encode a question and reflectionor transmission of the photon as answer options. Each question is represented by a photon in a transmission line with both ends returning to the user, and the answer is represented by reflection or transmission of this photon caused by the single photon transistor as described in another article. By solving the quantum Langevin equations for the 32 × 32-dimensional operators describing the single photon transistor the system is analysed. This analysis shows that the user privacy is maintained when the returning transmission lines are under the user's control. The probabilities for reflection and transmission are calculated to verify the behaviour of the answering mechanism. By using pulse trains instead of numbered lines to represent questions, the scalability of the system could be improved.
Abstract We propose a quantum-mechanical device consisting of transmon qubits connected to single-photon transmission lines that can be used to perform a boolean quantum private query on a database. Using numerical simulations verified by analytical calculations we analyse the dynamics of the query process in the proposed system by calculating the reflection and transmission probabilities of the photons encoding the questions. We show that the proposed device, which consists of experimentally available components, is capable of performing a quantum private query with high reliability and may form the basic building block of a lager-scale private search engine.
A security analysis of the recently introduced Quantum Private Query (QPQ) protocol is presented. The latter is a cheat sensitive quantum protocol to perform a private search on a classical database. It allows a user to retrieve an item from the database without revealing which item was retrieved, and at the same time it ensures data privacy of the database (the information that the user retrieves in a query is bounded). The security analysis is based on information-disturbance tradeoffs which show that whenever the provider tries to obtain information on the query, the query (encoded into a quantum system) is disturbed so that the person querying the database can detect the privacy violation. The security bounds are derived under the assumption that a unique answer corresponds to each query. To remove this assumption, some simple variants of the protocol are illustrated, and it is conjectured that analogous security bounds apply to them.
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.
A security analysis of the recently introduced Quantum Private Query (QPQ) protocol is presented. The latter is a cheat sensitive quantum protocol to perform a private search on a classical database. It allows a user to retrieve an item from the database without revealing which item was retrieved, and at the same time it ensures data privacy of the database (the information that the user retrieves in a query is bounded). The security analysis is based on information-disturbance tradeoffs which show that whenever the provider tries to obtain information on the query, the query (encoded into a quantum system) is disturbed so that the person querying the database can detect the privacy violation. The security bounds are derived under the assumption that a unique answer corresponds to each query. To remove this assumption, some simple variants of the protocol are illustrated, and it is conjectured that analogous security bounds apply to them.
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.
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.