Security bounds for decoy-state quantum key distribution with arbitrary photon-number statistics

Quantum Key Distribution (QKD) is an emerging cybersecurity technology that exploits the laws of quantum mechanics to generate unconditionally secure symmetric cryptographic keying material. The unique nature of QKD shows promise for high-security environments such as those found in banking, government, and the military. However, QKD systems often have implementation non-idealities that can negatively impact their performance and security. This article describes the development of a system-level model designed to study implementation non-idealities in commercially available decoy state enabled QKD systems. Specifically, this paper provides a detailed discussion of the decoy state protocol, its implementation, and its usage to detect sophisticated attacks, such as the photon number splitting attack. In addition, this work suggests an efficient and repeatable systems engineering methodology for understanding and studying communications protocols, architectures, operational configurations, and implementation tradeoffs in complex cyber systems.

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Phase-Matching Quantum Key Distribution with Discrete Phase Randomization

Entropy ◽

10.3390/e23050508 ◽

2021 ◽

Vol 23 (5) ◽

pp. 508

Author(s):

Xiaoxu Zhang ◽

Yang Wang ◽

Musheng Jiang ◽

Yifei Lu ◽

Hongwei Li ◽

...

Keyword(s):

Quantum Key Distribution ◽

Photon Number ◽

Key Distribution ◽

Continuous Phase ◽

Phase Matching ◽

Decoy State ◽

State Discrimination ◽

Discrete Phase ◽

And Performance ◽

Phase Randomization

The twin-field quantum key distribution (TF-QKD) protocol and its variations have been proposed to overcome the linear Pirandola–Laurenza–Ottaviani–Banchi (PLOB) bound. One variation called phase-matching QKD (PM-QKD) protocol employs discrete phase randomization and the phase post-compensation technique to improve the key rate quadratically. However, the discrete phase randomization opens a loophole to threaten the actual security. In this paper, we first introduce the unambiguous state discrimination (USD) measurement and the photon-number-splitting (PNS) attack against PM-QKD with imperfect phase randomization. Then, we prove the rigorous security of decoy state PM-QKD with discrete phase randomization. Simulation results show that, considering the intrinsic bit error rate and sifting factor, there is an optimal discrete phase randomization value to guarantee security and performance. Furthermore, as the number of discrete phase randomization increases, the key rate of adopting vacuum and one decoy state approaches infinite decoy states, the key rate between discrete phase randomization and continuous phase randomization is almost the same.

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Measurement-device-independent quantum key distribution with leaky sources

Scientific Reports ◽

10.1038/s41598-021-81003-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Weilong Wang ◽

Kiyoshi Tamaki ◽

Marcos Curty

Keyword(s):

Quantum Key Distribution ◽

Communication Systems ◽

Signal Transmission ◽

Information Leakage ◽

Key Distribution ◽

Time Frame ◽

Measurement Device ◽

Decoy State ◽

Unrealistic Assumption ◽

Measurement Device Independent

AbstractMeasurement-device-independent quantum key distribution (MDI-QKD) can remove all detection side-channels from quantum communication systems. The security proofs require, however, that certain assumptions on the sources are satisfied. This includes, for instance, the requirement that there is no information leakage from the transmitters of the senders, which unfortunately is very difficult to guarantee in practice. In this paper we relax this unrealistic assumption by presenting a general formalism to prove the security of MDI-QKD with leaky sources. With this formalism, we analyze the finite-key security of two prominent MDI-QKD schemes—a symmetric three-intensity decoy-state MDI-QKD protocol and a four-intensity decoy-state MDI-QKD protocol—and determine their robustness against information leakage from both the intensity modulator and the phase modulator of the transmitters. Our work shows that MDI-QKD is feasible within a reasonable time frame of signal transmission given that the sources are sufficiently isolated. Thus, it provides an essential reference for experimentalists to ensure the security of implementations of MDI-QKD in the presence of information leakage.

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