A New Quantum Private Query Protocol with Better Performance in Resisting Joint-Measurement Attack.

Quantum private query (QPQ) as a kind of protocol with strong practicability, its research depth is deepening. However, joint measurement (JM) attack poses a threat to the security of databases in protocol. Specifically, a malicious user can illegally obtain entries more than the average number of honest users from the database. Taking Jakobi et al.’s protocol as an example, a malicious user can obtain up to 500 bits from a database of 104 bits in one query instead of the expected 2.44 bits. In order to prevent JM attack, we design a new quantum private query protocol which has the similar procedure of raw oblivious key generation with Wei Chunyan et al.’s and Jakobi et al.’s. In our protocol, we add a step that Alice has to send back the measured qubits after some operation which ensures she must measure honestly. Therefore, our protocol can protect database security in theoretically, and the protocol can also improve the communication transmission distance because the photons Alice returns to Bob is re-prepared by her. Moreover, our protocol keeps the good peculiarities of QKD-based QPQs, e.g., its loss tolerant and robust against quantum memory attack.