Secret key rates for coherent attacks

Mertz, Markus; Kampermann, Hermann; Bratzik, Sylvia; Bruß, Dagmar

doi:10.1103/physreva.87.012315

Cited by 10 publications

(10 citation statements)

References 27 publications

(55 reference statements)

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“…If the main homodyne detector H the monitoring detector H ′ (see Fig. 4) are both imperfect with loss η D and noise of the variance V D , which is coupled to the signal with the ratio η D [40], then the quadratures measured by the detectors H and H ′ will be given by 15) and 16) respectively, where x 1 and x 2 are the quadrature values associated with the detector noise such that V ar(x 1 ) = V ar(x 2 ) ≡ V D . The weighted difference ∆x = gx ′ B − g ′ x ′ SCB will then be given by…”

Section: Appendix: Security Analysis Is Detailmentioning

confidence: 99%

“…Recently, continuous-variable (CV) [3] protocols of QKD (see [4] for review) were developed and implemented on the basis of squeezed [5][6][7] or coherent [8][9][10][11][12] states. The security of CV QKD protocols in the case of Gaussian modulation was then shown against collective attacks in the presence of channel noise [13,14], which also implies the security against the most general coherent attacks [15,16].…”

Section: Introductionmentioning

confidence: 98%

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Preventing side-channel effects in continuous-variable quantum key distribution

2016

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The role of the side channels in the continuous-variable quantum key distribution is studied. It is shown how the information leakage through a side channel from the trusted sender station increases the vulnerability of the protocols to the eavesdropping in the main quantum communication channel. Moreover, the untrusted noise infusion by an eavesdropper on the trusted receiving side breaks the security even for a purely attenuating main quantum channel. As a method to compensate for the effect of the side-channel leakage on the sender side, we suggest several types of manipulations on the side-channel input. It is shown that by applying the modulated coherent light on the input of the side channel that is optimally correlated to the modulation on the main signal and optionally, introducing additional squeezing in the case of the squeezed-state protocol, the negative influence of the lossy side channel on the sender side can be completely removed. For the trusted receiving side, the method of optimal monitoring of the residual noise from the side-channel noise infusion is suggested and shown to be able to completely eliminate the presence of the noisy side channel. We therefore prove that the side-channel effects can be completely removed using feasible operations if the trusted parties access the respective parts of the side channels. PACS numbers: 03.67.Hk, 03.67.Dd I. INTRODUCTIONQuantum key distribution (QKD) [1, 2] is a major communication application of quantum information theory aiming at the development of protocols for establishing secure channels protected by the laws of quantum physics. Such channels can then be used to share a secure key for classical symmetrical cryptographic systems. Recently, continuous-variable (CV) [3] protocols of QKD (see [4] for review) were developed and implemented on the basis of squeezed [5][6][7] or coherent [8][9][10][11][12] states. The security of CV QKD protocols in the case of Gaussian modulation was then shown against collective attacks in the presence of channel noise [13,14], which also implies the security against the most general coherent attacks [15,16].CV QKD protocols, however, suffer from various imperfections. The most threatening are the untrusted (i.e., being under full control of a potential eavesdropper) quantum channels, which are inclined to losses due to the attenuation and can add excess noise in the link. Such noise can also be detection noise indistinguishable from the effect of the channel. In security analysis it is then supposed that all the channel imperfections are due to the presence on an eavesdropper. It was an important step in the development of CV QKD when with the use of reverse reconciliation it was shown possible to establish asymptotically secure key transmission upon any pure channel loss [9], while noise remains limiting to the security of the protocols.However, the insecure quantum channel is not neces- * Electronic address: ivan.derkach01@upol.cz †

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Section: Appendix: Security Analysis Is Detailmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Preventing side-channel effects in continuous-variable quantum key distribution

2016

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“…Due to non-optimized decoy-state 2 It was conjectured that the mentioned proof method holds for general attacks too, not only for collective ones. Recently, an attempt to prove this conjecture was made in [48] and it was found that a few extra bits have to be sacrificed during privacy amplification to go from collective to general attacks. Table I.…”

Section: A State Of the Art And Comparisonmentioning

confidence: 99%

Security Bounds for Efficient Decoy-State Quantum Key Distribution

Lucamarini

Dynes

Fröhlich

et al. 2015

IEEE J. Select. Topics Quantum Electron.

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Abstract-Information-theoretical security of quantum key distribution (QKD) has been convincingly proven in recent years and remarkable experiments have shown the potential of QKD for real world applications. Due to its unique capability of combining high key rate and security in a realistic finite-size scenario, the efficient version of the BB84 QKD protocol endowed with decoy states has been subject of intensive research. Its recent experimental implementation finally demonstrated a secure key rate beyond 1 Mbps over a 50 km optical fiber. However the achieved rate holds under the restrictive assumption that the eavesdropper performs collective attacks. Here, we review the protocol and generalize its security. We exploit a map by Ahrens to rigorously upper bound the Hypergeometric distribution resulting from a general eavesdropping. Despite the extended applicability of the new protocol, its key rate is only marginally smaller than its predecessor in all cases of practical interest.

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“…In the more general case of collective attacks it is assumed that Eve can store her ancillary states in a quantum memory and perform an optimized collective measurement on the set of states after the measurement bases are revealed by Alice and Bob. It was also recently shown that collective attacks are no less effective than the most general coherent attacks [46,47], which is also valid for continuousvariable protocols in the asymptotic regime [48]. Thus, we establish security against the individual attacks to analytically estimate the region where security is lost, since insecurity against individual attacks is a sufficient condition for insecurity of the protocol against more sophisticated attacks such as collective and coherent attacks.…”

Section: Security Analysismentioning

confidence: 99%

Entanglement-based continuous-variable quantum key distribution with multimode states and detectors

2014

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Secure quantum key distribution with multimode Gaussian entangled states and multimode homodyne detectors is proposed. In general the multimode character of both the sources of entanglement and the homodyne detectors can cause a security break even for a perfect channel when trusted parties are unaware of the detection structure. Taking into account the multimode structure and potential leakage of information from a homodyne detector reduces the loss of security to some extent. We suggest the symmetrization of the multimode sources of entanglement as an efficient method allowing us to fully recover the security irrespectively to multimode structure of the homodyne detectors. Further, we demonstrate that by increasing the number of the fluctuating but similar source modes the multimode protocol stabilizes the security of the quantum key distribution. The result opens the pathway towards quantum key distribution with multimode sources and detectors.

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Secret key rates for coherent attacks

Cited by 10 publications

References 27 publications

Preventing side-channel effects in continuous-variable quantum key distribution

Preventing side-channel effects in continuous-variable quantum key distribution

Security Bounds for Efficient Decoy-State Quantum Key Distribution

Entanglement-based continuous-variable quantum key distribution with multimode states and detectors

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