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In this letter, first, we investigate the security of a continuous-variable quantum cryptographic scheme with a postselection process against individual beam splitting attack. It is shown that the scheme can be secure in the presence of the…

Quantum Physics · Physics 2009-11-10 Ryo Namiki , Takuya Hirano

The unconditional security of continuous-variable quantum key distribution is established for all schemes based on the estimation of the channel loss and excess noise. It is proved that, in the limit of large keys, Gaussian attacks are…

Quantum Physics · Physics 2010-12-15 Anthony Leverrier , Evgueni Karpov , Philippe Grangier , Nicolas J. Cerf

An intercept-resend attack on a continuous-variable quantum-key-distribution protocol is investigated experimentally. By varying the interception fraction, one can implement a family of attacks where the eavesdropper totally controls the…

A fully general approach to the security analysis of continuous-variable quantum key distribution (CV-QKD) is presented. Provided that the quantum channel is estimated via the covariance matrix of the quadratures, Gaussian attacks are shown…

Quantum Physics · Physics 2009-11-13 Raul Garcia-Patron , Nicolas J. Cerf

We analyze the asymptotic security of the family of Gaussian modulated Quantum Key Distribution protocols for Continuous Variables systems. We prove that the Gaussian unitary attack is optimal for all the considered bounds on the key rate…

Quantum Physics · Physics 2009-11-13 Miguel Navascues , Frederic Grosshans , Antonio Acin

We investigate the security against collective attacks of a continuous variable quantum key distribution scheme in the asymptotic key limit for a realistic setting. The quantum channel connecting the two honest parties is assumed to be…

Quantum Physics · Physics 2007-12-12 Matthias Heid , Norbert Lütkenhaus

We consider continuous-variable quantum key distribution with discrete-alphabet encodings. In particular, we study protocols where information is encoded in the phase of displaced coherent (or thermal) states, even though the results can be…

Quantum Physics · Physics 2021-01-18 Panagiotis Papanastasiou , Stefano Pirandola

We provide a simple description of the most general collective Gaussian attack in continuous-variable quantum cryptography. In the scenario of such general attacks, we analyze the asymptotic secret-key rates which are achievable with…

Quantum Physics · Physics 2008-12-03 Stefano Pirandola , Samuel L. Braunstein , Seth Lloyd

We present here an information theoretic study of Gaussian collective attacks on the continuous variable key distribution protocols based on Gaussian modulation of coherent states. These attacks, overlooked in previous security studies,…

Quantum Physics · Physics 2009-11-10 Frederic Grosshans

Recently, we have shown the advantages of two-way quantum communications in continuous variable quantum cryptography. Thanks to this new approach, two honest users can achieve a non-trivial security enhancement as long as the Gaussian…

Quantum Physics · Physics 2008-09-18 Stefano Pirandola , Stefano Mancini , Seth Lloyd , Samuel L. Braunstein

We investigate the performance of Gaussianmodulated coherent-state QKD protocols in the presence of canonical attacks, which are collective Gaussian attacks resulting in Gaussian channels described by one of the possible canonical forms. We…

Quantum Physics · Physics 2021-09-07 Panagiotis Papanastasiou , Carlo Ottaviani , Stefano Pirandola

Establishing the security of continuous-variable quantum key distribution against general attacks in a realistic finite-size regime is an outstanding open problem in the field of theoretical quantum cryptography if we restrict our attention…

Quantum Physics · Physics 2017-05-17 Anthony Leverrier

We present strong attacks against quantum key distribution schemes which use quantum memories and quantum gates to attack directly the final key. We analyze a specific attack of this type, for which we find the density matrices available to…

Quantum Physics · Physics 2016-09-08 E. Biham , T. Mor

We consider two-way continuous-variable quantum key distribution, studying its security against general eavesdropping strategies. Assuming the asymptotic limit of many signals exchanged, we prove that two-way Gaussian protocols are immune…

Quantum Physics · Physics 2017-05-09 Carlo Ottaviani , Stefano Pirandola

Continuous-variable quantum key distribution provides a theoretical unconditionally secure solution to distribute symmetric keys among users in a communication network. However, the practical devices used to implement these systems are…

Quantum Physics · Physics 2026-05-06 Daniel Pereira , Vana Pezelj , Florian Prawits , Hannes Hübbel

We investigate the asymptotic security of one-way continuous variable quantum key distribution against Gaussian two-mode coherent attacks. The one-way protocol is implemented by arranging the channel uses in two-mode blocks. By applying…

Quantum Physics · Physics 2017-05-10 Carlo Ottaviani , Stefano Mancini , Stefano Pirandola

In this thesis we study the finite-size analysis of two continuous-variables quantum key distribution schemes. The first one is the one-way protocol using Gaussian modulation of thermal states and the other is the…

Quantum Physics · Physics 2019-06-13 Panagiotis Papanastasiou

Harnessing quantum processes is an efficient method to generate truly indeterministic random numbers, which are of fundamental importance for cryptographic protocols, security applications or Monte-Carlo simulations. Recently, quantum…

Quantum Physics · Physics 2019-11-14 Johannes Thewes , Carolin Lüders , Marc Aßmann

We give the first composable security proof for continuous-variable quantum key distribution with coherent states against collective attacks. Crucially, in the limit of large blocks the secret key rate converges to the usual value computed…

Quantum Physics · Physics 2015-03-06 Anthony Leverrier

The Gaussian quantum key distribution protocol based on coherent states and heterodyne detection [Phys. Rev. Lett. 93, 170504 (2004)] has the advantage that no active random basis switching is needed on the receiver's side. Its security is,…

Quantum Physics · Physics 2009-11-13 J. Sudjana , L. Magnin , R. Garcia-Patron , N. J. Cerf
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