Security Bounds for Efficient Decoy-State Quantum Key Distribution

Lucamarini, Marco; Dynes, J. F.; Fröhlich, B.; Shields, A. J.

doi:10.1109/jstqe.2015.2394774

Cited by 24 publications

(30 citation statements)

References 55 publications

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“…In the asymptotic limit, this is justified by the equality y 1,1 Z = y 1,1 X . In the finite-size case, we can use the fact that, provided that the sample in the X basis is smaller than the one in the Z basis, the lower bound to y 1,1 X also represents a lower bound to y 1,1 Z [6]. The condition about the sizes of the two samples in the bases Z and X is fulfilled in our experiment, due to the higher photon flux used in the Z basis.…”

Section: Decoy State Estimationmentioning

confidence: 93%

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mentioning

confidence: 99%

“…Therefore the vast majority of the attacks performed so far have targeted Bob's single photon detectors [3][4][5][6][7]. 13] is a recent form of Quantum Cryptography conceived to remove the problem of detector vulnerability.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Quantum key distribution without detector vulnerabilities using optically seeded lasers

Comandar¹,

Lucamarini²,

Fröhlich³

et al. 2016

Nature Photon

247

193

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Security in quantum cryptography [1, 2] is continuously challenged by inventive attacks [3][4][5][6][7] targeting the real components of a cryptographic setup, and duly restored by new countermeasures [8][9][10] to foil them. Due to their high sensitivity and complex design, detectors are the most frequently attacked components. Recently it was shown that two-photon interference [11] from independent light sources can be exploited to avoid the use of detectors at the two ends of the communication channel [12,13]. This new form of detection-safe quantum cryptography, called Measurement-Device-Independent Quantum Key Distribution (MDI-QKD), has been experimentally demonstrated [13][14][15][16][17][18], but with modest delivered key rates.Here we introduce a novel pulsed laser seeding technique to obtain high-visibility interference from gain-switched lasers and thereby perform quantum cryptography without detector vulnerabilities with unprecedented bit rates, in excess of 1 Mb/s. This represents a 2 to 6 orders of magnitude improvement over existing implementations and for the first time promotes the new scheme as a practical resource for quantum secure communications. * marco.lucamarini@crl.toshiba.co.uk arXiv:1509.08137v2 [quant-ph] In Quantum Cryptography, a sender Alice transmits encoded quantum signals to a receiver Bob, who measures them and distils a secret string of bits with the sender via public discussion [1].Ideally, the use of quantum signals guarantees the information-theoretical security of the communication [2]. In practice, however, Quantum Cryptography is implemented with real components, which can deviate from the ideal description. This can be exploited to circumvent the quantum protection if the users are unaware of the problem [19].Usually the most complex components are also the most vulnerable. Therefore the vast majority of the attacks performed so far have targeted Bob's single photon detectors [3][4][5][6][7]. 13] is a recent form of Quantum Cryptography conceived to remove the problem of detector vulnerability. As depicted in Fig. 1(a), two light pulses are independently encoded and sent by Alice and Bob to a central node, Charlie. This is similar to a quantum access network configuration [20], but in MDI-QKD the central node does not need to be trusted and could even attempt to steal information from Alice and Bob. To follow the MDI-QKD protocol, Charlie must let the two light pulses interfere at the beam splitter inside his station and then measure them. The result can disclose the correlation between the bits encoded by the users, but not their actual values, which therefore remain secret. If Charlie violates the protocol and measures the pulses separately, he can learn the absolute values of the bits, but not their correlation. Therefore he cannot announce the correct correlation to the users, who will then unveil his attempt through public discussion.Irrespective of Charlie's choice, the users' apparatuses no longer need a detector and the detection vulnerability of Quantum Cryp...

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Section: Decoy State Estimationmentioning

confidence: 93%

“…

…”

mentioning

confidence: 99%

See 1 more Smart Citation

Quantum key distribution without detector vulnerabilities using optically seeded lasers

Comandar¹,

Lucamarini²,

Fröhlich³

et al. 2016

Nature Photon

247

193

View full text Add to dashboard Cite

show abstract

“…42,43 Among those protocols, the security of decoy-state BB84 QKD has been extended to cover coherent attacks, for realistic block sizes and with a minimal sacrifice in the secret key rate. 44,45 Unfortunately, for coherent-one-way, the best security proof against coherent attacks currently gives a secret key rate that only scales quadratically with the loss. 46 For CV-QKD with coherent states and heterodyne detection, a composable security proof against the most general attacks has recently been provided, 47 but the current proof techniques do not allow a positive key rate for realistic block sizes in this case.…”

Section: Main Protocols and Implementationsmentioning

confidence: 99%

Practical challenges in quantum key distribution

Diamanti¹,

Lo²,

Qi³

et al. 2016

npj Quantum Inf

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627

468

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Quantum key distribution (QKD) promises unconditional security in data communication and is currently being deployed in commercial applications. Nonetheless, before QKD can be widely adopted, it faces a number of important challenges such as secret key rate, distance, size, cost and practical security. Here, we survey those key challenges and the approaches that are currently being taken to address them. For thousands of years, human beings have been using codes to keep secrets. With the rise of the Internet and recent trends to the Internet of Things, our sensitive personal financial and health data as well as commercial and national secrets are routinely being transmitted through the Internet. In this context, communication security is of utmost importance. In conventional symmetric cryptographic algorithms, communication security relies solely on the secrecy of an encryption key. If two users, Alice and Bob, share a long random string of secret bits-the key-then they can achieve unconditional security by encrypting their message using the standard one-time-pad encryption scheme. The central question then is: how do Alice and Bob share a secure key in the first place? This is called the key distribution problem. Unfortunately, all classical methods to distribute a secure key are fundamentally insecure because in classical physics there is nothing preventing an eavesdropper, Eve, from copying the key during its transit from Alice to Bob. On the other hand, standard asymmetric or public-key cryptography solves the key distribution problem by relying on computational assumptions such as the hardness of factoring. Therefore, such schemes do not provide information-theoretic security because they are vulnerable to future advances in hardware and algorithms, including the construction of a large-scale quantum computer.

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“…The idea of decoy state-based QKD protocols has been proposed and proved to be a good solution for substantially improving the performance of QKD based on weak coherent pulses (WCPs) to overcome the inherent shortage of using commercial available laser sources [8]- [10]. The security proof based on the uncertainty relation for smooth entropies [7], [11] has been applied in [12] and [13] to decoy state-based protocols. On the experimental side, QKD demonstration over long distances has been achieved for both optical fiber and free-space optical (FSO) links.…”

Section: Introductionmentioning

confidence: 99%

Secret Key Rates and Optimization of BB84 and Decoy State Protocols Over Time-Varying Free-Space Optical Channels

2016

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We optimize secret key rates (SKRs) of weak coherent pulse (WCP)-based quantum key distribution (QKD) over time-varying free-space optical channels affected by atmospheric turbulence. The random irradiance fluctuation due to scintillation degrades the SKR performance of WCP-based QKD, and to improve the SKR performance, we propose an adaptive scheme in which transmit power is changed in accordance with the channel state information. We first optimize BB84 and decoy statebased QKD protocols for different channel transmittances. We then present our adaptation method, to overcome scintillation effects, of changing the source intensity based on channel state predictions from a linear autoregressive model while ensuring the security against the eavesdropper. By simulation, we demonstrate that by making the source adaptive to the time-varying channel conditions, SKRs of WCP-based QKD can be improved up to over 20%.

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Security Bounds for Efficient Decoy-State Quantum Key Distribution

Cited by 24 publications

References 55 publications

Quantum key distribution without detector vulnerabilities using optically seeded lasers

Quantum key distribution without detector vulnerabilities using optically seeded lasers

Practical challenges in quantum key distribution

Secret Key Rates and Optimization of BB84 and Decoy State Protocols Over Time-Varying Free-Space Optical Channels

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