Physical Review Applied

Russian Researchers Patent Detector Blinding Protection for Quantum Key Distribution Systems

Engineers from SFB Lab and the Center for Quantum Technologies at Moscow State University have developed a new method to protect quantum key distribution systems against detector blinding attacks. The technique not only detects the attack but also preserves the secure portion of the generated key instead of discarding the entire key after an alarm. The approach works by randomly varying the quantum efficiency of single-photon detectors at the receiver side, forcing an attacker to leave detectable traces such as erroneous or double clicks. These statistical anomalies allow the system to estimate the number of potentially compromised bits and remove them during privacy amplification. The solution has been granted Russian patent RU 2 856 208 C1 and accepted for publication in Physical Review Applied. It was validated on commercial off-the-shelf detectors and requires no changes to the optical scheme, making it compatible with a wide range of existing QKD hardware.