  In this paper, we introduce a quantum-secured single-pixel imaging (QS-SPI)
technique designed to withstand spoofing attacks, wherein adversaries attempt
to deceive imaging systems with fake signals. Unlike previous quantum-secured
protocols that impose a threshold error rate limiting their operation, even
with the existence of true signals, our approach not only identifies spoofing
attacks but also facilitates the reconstruction of a true image. Our method
involves the analysis of a specific mode correlation of a photon-pair, which is
independent of the mode used for image construction, to check security. Through
this analysis, we can identify both the targeted image region by the attack and
the type of spoofing attack, enabling reconstruction of the true image. A
proof-of-principle demonstration employing polarization-correlation of a
photon-pair is provided, showcasing successful image reconstruction even under
the condition of spoofing signals 2000 times stronger than the true signals. We
expect our approach to be applied to quantum-secured signal processing such as
quantum target detection or ranging.
