| （英） |
The bright illumination attack exploits the imperfections of photon detectors (Avalanche Photodiodes, APDs) used in Quantum Key Distribution (QKD) systems, and it is considered feasible with current technology. By continuously sending strong light to the receiver (Bob), an eavesdropper (Eve) can intentionally control the detector's behavior and steal secret key information without being noticed by the legitimate sender and receiver. A well-known countermeasure is to install a power meter on Bob's device to monitor suspicious light. However, there is little experimental evidence that can detect and prevent arbitrary bright illumination from Eve, and at present, it is difficult to say that this countermeasure is foolproof. In this paper, we demonstrate that in BB84 systems with passive and asymmetric basis selection, the intensity of light Eve is allowed to send is bounded from above and below by parameters derived from the detectors. In other words, in BB84 systems with passive and asymmetric basis selection, Arbitrary lights from Eve are split asymmetrically, and under certain conditions, some detectors cannot be controlled. This suggests the possibility of detecting the bright illumination attack without using a power meter. We also discuss the advantages of combining this proposal with the use of a power meter. |