Time-shift attack in practical quantum cryptosystems

By Bing Qi, Chi-Hang Fred Fung, Hoi-Kwong Lo, Xiongfeng Ma. Quantum information & computation, 2005

333 citations recorded by the source corpus.

Recently, a new type of attack, which exploits the efficiency mismatch of two single photon detectors (SPD) in a quantum key distribution (QKD) system, has been proposed. In this paper, we propose another "time-shift" attack that exploits the same imperfection. In our attack, Eve shifts the arrival time of either the signal pulse or the synchronization pulse or both between Alice and Bob. In particular, in a QKD system where Bob employs time-multiplexing technique to detect both bit "0" and bit "1" with the same SPD, Eve, in some circumstances, could acquire full information on the final key without introducing any error. In addition, we prove that if Alice and Bob are unaware of our attack, the final key they share is insecure. We emphasize that our attack is simple and feasible with current technology. Finally, we discuss some counter measures against our and earlier attacks.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/f42d3177d9dbb524127dc7f36443d93cdf0abc26

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Citations in the corpus

Quantum Cryptography (2006, positive): “This way Eve can get information about the sent bits without measuring the quantum signal [8] [9].”
Secure quantum key distribution (2014, background): “Indeed, this has been the case in recent attacks against certain commercial and research QKD set-ups [76–91], where Eve employed some imperfections in the devices, specially in the single-photon detectors, to hack the sys-tem.”
Hacking commercial quantum cryptography systems by tailored bright illumination (2010, background): “In contrast, a more implementation-friendly attack is the time-shift attack 15 based on detector eﬃ-ciency mismatch 16 .”
Advances in quantum cryptography (2019, neutral): “[540] suggested a different attack based on DEM with the time parameter, which they called the time-shift attack.”
Secure quantum key distribution with realistic devices (2020, background): “…Detection Detector Theory 2005 Trojan horse (Gisin et al., 2006; Vakhitov et al., 2001) Source&Detection Backflection light Theory 2006 Time shift (Qi et al., 2007a; Zhao et al., 2008) Detection Detector Experiment∗ 2007 Time side-channel (Lamas-Linares and Kurtsiefer, 2007) Detection Timing…”
The security of practical quantum key distribution (2008, background): “A possible solution consists in including the calibration of the devices in the protocol itself; the price to pay seems to be a complication of the setup (Qi et al., 2007).”