Hacking single-photon avalanche detectors in quantum key distribution via pulse illumination

Abstract

Quantum key distribution (QKD) has been proved to be information-theoretically secure in theory. Unfortunately, the imperfect devices in practice compromise its security. Thus, to improve the security property of practical QKD systems, a commonly used method is to patch the loopholes in the existing QKD systems. However, in this work, we show an adversary’s capability of exploiting the imperfection of the patch itself to bypass the patch. Specifically, we experimentally demonstrate that, in the detector under test, the patch of photocurrent monitor against the detector blinding attack can be defeated by the pulse illumination attack proposed in this paper. We also analyze the secret key rate under the pulse illumination attack, which theoretically confirmed that Eve can conduct the attack to learn the secret key. This work indicates the importance of inspecting the security loopholes in a detection unit to further understand their impacts on a QKD system. The method of pulse illumination attack can be a general testing item in the security evaluation standard of QKD.

Strong pulse illumination hacks self-differencing avalanche photodiode detectors in a high-speed quantum key distribution system

“…brightlight attack, it may be bypassed by a group of blinding pulses that are used in the pulse illumination attack. Specifically, a group of blinding pulses accumulatively introduces a high photocurrent may be averaged before sensing by a photocurrent monitor [30]. Thus, the instant high photocurrent may lower the bais voltage across the APD to blind the SD APD detector.…”

Nonclassical Attack on a Quantum Key Distribution System

“…For example, the typical DCP value for id210 and id230 photodetectors is 40 and 50 Hz, respectively [ 18 , 19 ]. Such photodetectors are used in the Clavis 2 and Clavis 3 QKDS [ 20 , 21 , 22 , 23 , 24 ]. We applied the real characteristics of the id230 photodetector to our calculations (see Figure 10 ).…”

A Review of Security Evaluation of Practical Quantum Key Distribution System

“…Another typical time-related attack is the dead-time attack [52]. Instead of tampering the signal state, Eve sends a faked state with multiple photons, for example |− in Figure 9a By tailoring the intensity of the faked state, Eve also can control the information bit via the blinding attack [26,55,56]. Specifically, Eve first applies a strong continuous wave or pulsed light to transfer the SPD from the Geiger mode to the linear mode, then the SPD is no longer sensitive to a single photon.…”

“…By tailoring the intensity of the faked state, Eve also can control the information bit via the blinding attack [ 26 , 55 , 56 ]. Specifically, Eve first applies a strong continuous wave or pulsed light to transfer the SPD from the Geiger mode to the linear mode, then the SPD is no longer sensitive to a single photon.…”

“… The illustration of the blinding attack. ( a ) The equivalent circuit related to the APD in a detector, reprinted from [ 56 ]; ( b ) the working modes of a APD, reprinted from Ref. [ 26 ].…”