The quantum private comparison (QPC) protocol is an important research issue in the quantum secure computation field. The participants obtain the relational comparison between each other private messages without leaking any secret information by QPC protocol. In order to improve the practicality of quantum secure communication protocol, the semi-quantum concept was proposed to let the users who only have limited quantum capabilities (called the classical users) can also achieve the quantum secure communication protocol. According to the semi-quantum concept, this study proposes a semi-quantum private comparison (SQPC) protocol using a measurement property of a graph state https://www.w3.org/1998/Math/MathML" display="inline"> |G ⟩ 123 = 1 2 2 000 + 001 + 010 − 011 + 100 − 101 − 110 − | 111 ⟩ 123 https://www.w3.org/1999/xlink" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003460763/a1dd00af-5f0d-42a5-a080-674b9e863cf3/content/inline-math11_1.tif "/> . The proposed SQPC protocol lets the two classical users can compare whether their private messages are equal or not with the assistance of a dishonest three-party quantum user (TP), in which TP owns the complete quantum capabilities and the classical users only equip the two quantum devices including (1) Hadamard operation and (2) Z-basis https://www.w3.org/1998/Math/MathML" display="inline"> 0 , | 1 ⟩ https://www.w3.org/1999/xlink" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003460763/a1dd00af-5f0d-42a5-a080-674b9e863cf3/content/inline-math11_2.tif "/> measurement. Because the one-way qubit transmission is adopted, the proposed SQPC protocol is free from quantum Trojan horse attack. Moreover, a security analysis also is given to prove that the proposed SQPC is robust under the collective attack.

CRC Press eBooksDec 12, 20231 citation

Authenticated multi-user quantum private query using GHZ states

Ying Zhang, Chen‐Ming Bai, Sujuan Zhang

Abstract Quantum private query (QPQ) enables users to extract desired entries from a database without decrypting its content, while simultaneously safeguarding both user query privacy and database security. In this paper, we propose a multi-user QPQ protocol based on Greenberger–Horne–Zeilinger (GHZ) states, which allows two distant users, Alice 1 and Alice 2 , to jointly query the same database entry. The protocol introduces a semi-trusted third party to prepare and distribute the GHZ states, and employs a bidirectional authentication mechanism to ensure the authenticity of the communicating entities. Security analysis demonstrates that the proposed protocol effectively resists both internal and external attacks and exhibits resilience against quantum computing attacks. Compared with existing QPQ schemes, the protocol significantly improves user privacy and database security while supporting multi-user collaborative queries.

Physica ScriptaJul 3, 20261 citation