Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Análise da seguridade dos sistemas cuánticos de distribución de clave

Weilong Wang

Published Feb 28, 2019• 0 citations
OpenAlex

Abstract

We will analyse the security of practical Quantum Key Distribution (QKD) protocols based on Weak Coherent Pulses (WCP) or entangled states in the finite-key regime. Such analysis will take into account the typical imperfections that are presented both in the transmitter and receiver of the experimental realisations. The goal is to achieve tight finite-key security bounds for both the secret key rate and distance that can be achieved with practical QKD systems.

Related papers

Finite-key security analysis of quantum cryptographic protocols

Weilong Wang

We will analyse the security of practical Quantum Key Distribution (QKD) protocols based on Weak Coherent Pulses (WCP) or entangled states in the finite-key regime. Such analysis will take into account the typical imperfections that are presented both in the transmitter and receiver of the experimental realisations. The goal is to achieve tight finite-key security bounds for both the secret key rate and distance that can be achieved with practical QKD systems.

•Jan 1, 2019•0 citations

Security of Quantum Key Distribution with Weak Coherent Pulses

駿 川上

Quantum key distribution (QKD) allows two distant parties to share a secret key and realizes a communication with information-theoretic security by combining it with one-time-pad encryption.Since the Bennett-Brassard 1984 (BB84) protocol was proposed, a large number of researches on QKD have been conducted from both aspects of theory and implementations.For implementations of QKD, weak coherent pulses (WCP) are heavily used as optical signals because they are easily generated by typical lasers and attenuators.The security for QKD with WCP has been also studied along the development of the implementations.In this thesis, the security analysis of the QKD with WCP is considered and further developed from two aspects.First, the security of the differential-quadrature-phase-shift (DQPS) protocol is proved.The DQPS protocol has essentially the same set up as the phase-encoding BB84 (PE-BB84) protocol, which is one of the most frequently demonstrated protocols.Since the known proof techniques for the BB84 protocol is not directly applicable, a modified approach is developed which is suitable for the DQPS protocol.As a result, the advantage of the DQPS protocol in the key generation rate over the PE-BB84 protocol is shown in the asymptotic limit where the size of communication data is assumed to be infinite.Second, a new method for security analysis with finite-key size is proposed as a suitable method for QKD protocols using WCP.Differently from the current method based on simple random sampling, the proposed method relies on Bernoulli sampling, which is associated with binomial distribution.The security of the BB84 protocol is proved by using the Bernoulli-sampling method, enabling a simpler analysis with a smaller number of parameters to be estimated compared to the method with simple random sampling.The required number of detected signals to generate a secret key is shown to be smaller than 10 4 , which is drastic improvement from the number ∼ 10 7 obtained in the previous result.The proposed method is also applied to the DQPS protocol, and its advantage over the PE-BB84 protocol is certified even in the finite-key regime.i

•Mar 23, 2017•1 citation

Contribuições à análise de segurança de protocolos de criptografia quântica

Francisco Franklin Sousa Rios

This thesis can be divided in three parts: I) Security analysis of quantum bit commitment (QBC). II) Quantum-chaotic key distribution (QCKD) using multiphoton pulses. III) Homodyne detection of weak coherent states. In respect to the security analysis of quantum bit commitment, it was shown that if one takes into account the spectral width of the light pulses and the frequency dependence of optical quantum gates, the QBC, contrary to what was previously considered, is not unconditionally insecure. In what concerns the QCKD, the usage of coherent states with continuous phase forces the eavesdropper to use an attack based on quantum homodyne tomography. In this case, it was shown that the transmitter can use coherent states with mean photon number much larger than the value traditionally used in quantum key distribution QKD, and the QCKD will still be secure. At last, in the homodyne detection part, an experiment was realized showing the detection, by an optical receiver based on PIN photodiode, of an analog modulating signal carried by a strongly attenuated coherent state.

•Jun 29, 2018•0 citations

Analytical Bounds for Decoy-State Quantum Key Distribution With Discrete Phase Randomization

Zhaohui Liu, Ahmed Q. Lawey, Mohsen Razavi

We analyze the performance of quantum key distribution (QKD) protocols that rely on discrete phase randomization (DPR). For many QKD protocols that rely on weak coherent pulses (WCPs), continuous phase randomization is assumed, which simplifies the security proofs for such protocols. However, it is challenging to achieve such a perfect phase randomization in practice. As an alternative, we can select a discrete set of global phase values for WCPs, but we need to redo the security analysis for such a source. While security proofs incorporating DPR have been established for several QKD protocols, they often rely on computationally intensive numerical optimizations. To address this issue, in this study, we derive analytical bounds on the secret key generation rate of BB84 and measurement-device-independent QKD protocols in the DPR setting. Our analytical bounds closely match the results obtained from more cumbersome numerical methods in the regions of interest.

arXiv:2508.14664•IEEE Journal on Selected Areas in Communications•Jan 1, 2026•1 citation

Limitations on Practical Quantum Cryptography

Gilles Brassard A, Norbert Lütkenhaus, Tal Mor +1 more

We provide limits to practical quantum key distribution, taking into account channel losses, a realistic detection process, and imperfections in the "qubits" sent from the sender to the receiver. As we show, even quantum key distribution with perfect qubits might not be achievable over long distances when the other imperfections are taken into account. Furthermore, existing experimental schemes (based on weak pulses) currently do not offer unconditional security for the reported distances and signal strength. Finally we show that parametric down-conversion offers enhanced performance compared to its weak coherent pulse counterpart.

arXiv:quant-ph/9911054•Physical Review Letters•Aug 7, 2000•1,220 citations

Finite-key security analysis of decoy-state QKD with source and detector imperfections

Xoel Sixto, Guillermo Currás-Lorenzo, Margarida Pereira +3 more

Decoy-state quantum key distribution (QKD) is the most widely adopted approach for overcoming the limitations of imperfect single-photon sources. However, existing security proofs typically either neglect important device imperfections or rely on assumptions that are difficult to justify in realistic high-speed implementations, such as the independent and identically distributed nature of the emitted signals. In this work, we combine and extend several recent theoretical advances to provide a comprehensive analytical finite-key security proof for decoy-state QKD that simultaneously incorporates multiple practically relevant transmitter and receiver imperfections, including state-preparation flaws, bit and basis side-channel leakage and correlations, setting-independent intensity fluctuations, and detection-efficiency mismatches.

quant-pharXiv:2606.29943•Jun 30, 2026•0 citations
We will analyse the security of practical Quantum Key Distribution (QKD) protocols based on Weak Coherent Pulses (WCP) or entangled states in the finite-key regime. Such analysis will take into account the typical imperfections that are presented both in the transmitter and receiver of the experimental realisations. The goal is to achieve tight finite-key security bounds for both the secret key rate and distance that can be achieved with practical QKD systems.
Quantum key distribution (QKD) allows two distant parties to share a secret key and realizes a communication with information-theoretic security by combining it with one-time-pad encryption.Since the Bennett-Brassard 1984 (BB84) protocol was proposed, a large number of researches on QKD have been conducted from both aspects of theory and implementations.For implementations of QKD, weak coherent pulses (WCP) are heavily used as optical signals because they are easily generated by typical lasers and attenuators.The security for QKD with WCP has been also studied along the development of the implementations.In this thesis, the security analysis of the QKD with WCP is considered and further developed from two aspects.First, the security of the differential-quadrature-phase-shift (DQPS) protocol is proved.The DQPS protocol has essentially the same set up as the phase-encoding BB84 (PE-BB84) protocol, which is one of the most frequently demonstrated protocols.Since the known proof techniques for the BB84 protocol is not directly applicable, a modified approach is developed which is suitable for the DQPS protocol.As a result, the advantage of the DQPS protocol in the key generation rate over the PE-BB84 protocol is shown in the asymptotic limit where the size of communication data is assumed to be infinite.Second, a new method for security analysis with finite-key size is proposed as a suitable method for QKD protocols using WCP.Differently from the current method based on simple random sampling, the proposed method relies on Bernoulli sampling, which is associated with binomial distribution.The security of the BB84 protocol is proved by using the Bernoulli-sampling method, enabling a simpler analysis with a smaller number of parameters to be estimated compared to the method with simple random sampling.The required number of detected signals to generate a secret key is shown to be smaller than 10 4 , which is drastic improvement from the number ∼ 10 7 obtained in the previous result.The proposed method is also applied to the DQPS protocol, and its advantage over the PE-BB84 protocol is certified even in the finite-key regime.i
This thesis can be divided in three parts: I) Security analysis of quantum bit commitment (QBC). II) Quantum-chaotic key distribution (QCKD) using multiphoton pulses. III) Homodyne detection of weak coherent states. In respect to the security analysis of quantum bit commitment, it was shown that if one takes into account the spectral width of the light pulses and the frequency dependence of optical quantum gates, the QBC, contrary to what was previously considered, is not unconditionally insecure. In what concerns the QCKD, the usage of coherent states with continuous phase forces the eavesdropper to use an attack based on quantum homodyne tomography. In this case, it was shown that the transmitter can use coherent states with mean photon number much larger than the value traditionally used in quantum key distribution QKD, and the QCKD will still be secure. At last, in the homodyne detection part, an experiment was realized showing the detection, by an optical receiver based on PIN photodiode, of an analog modulating signal carried by a strongly attenuated coherent state.
We analyze the performance of quantum key distribution (QKD) protocols that rely on discrete phase randomization (DPR). For many QKD protocols that rely on weak coherent pulses (WCPs), continuous phase randomization is assumed, which simplifies the security proofs for such protocols. However, it is challenging to achieve such a perfect phase randomization in practice. As an alternative, we can select a discrete set of global phase values for WCPs, but we need to redo the security analysis for such a source. While security proofs incorporating DPR have been established for several QKD protocols, they often rely on computationally intensive numerical optimizations. To address this issue, in this study, we derive analytical bounds on the secret key generation rate of BB84 and measurement-device-independent QKD protocols in the DPR setting. Our analytical bounds closely match the results obtained from more cumbersome numerical methods in the regions of interest.
We provide limits to practical quantum key distribution, taking into account channel losses, a realistic detection process, and imperfections in the "qubits" sent from the sender to the receiver. As we show, even quantum key distribution with perfect qubits might not be achievable over long distances when the other imperfections are taken into account. Furthermore, existing experimental schemes (based on weak pulses) currently do not offer unconditional security for the reported distances and signal strength. Finally we show that parametric down-conversion offers enhanced performance compared to its weak coherent pulse counterpart.
Decoy-state quantum key distribution (QKD) is the most widely adopted approach for overcoming the limitations of imperfect single-photon sources. However, existing security proofs typically either neglect important device imperfections or rely on assumptions that are difficult to justify in realistic high-speed implementations, such as the independent and identically distributed nature of the emitted signals. In this work, we combine and extend several recent theoretical advances to provide a comprehensive analytical finite-key security proof for decoy-state QKD that simultaneously incorporates multiple practically relevant transmitter and receiver imperfections, including state-preparation flaws, bit and basis side-channel leakage and correlations, setting-independent intensity fluctuations, and detection-efficiency mismatches.