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Quantum key distribution promises unconditionally secure communications. However, as practical devices tend to deviate from their specifications, the security of some practical systems is no longer valid. In particular, an adversary can…

Quantum Physics · Physics 2015-06-16 Marcos Curty , Feihu Xu , Wei Cui , Charles Ci Wen Lim , Kiyoshi Tamaki , Hoi-Kwong Lo

The security of quantum key distribution (QKD) is quantified by a parameter $\varepsilon>0$, which -- under well-defined physical assumptions -- can be bounded explicitly. This contrasts with computationally secure schemes, where security…

Quantum Physics · Physics 2025-09-18 Carla Ferradini , Martin Sandfuchs , Ramona Wolf , Renato Renner

Quantum cryptography allows one to distribute a secret key between two remote parties using the fundamental principles of quantum mechanics. The well-known established paradigm for the quantum key distribution relies on the actual…

Quantum Physics · Physics 2015-05-13 Tae-Gon Noh

We present a simple method to obtain an upper bound on the achievable secret key rate in quantum key distribution (QKD) protocols that use only unidirectional classical communication during the public-discussion phase. This method is based…

Quantum Physics · Physics 2009-11-13 Tobias Moroder , Marcos Curty , Norbert Lütkenhaus

The appealing feature of quantum key distribution (QKD), from a cryptographic viewpoint, is the ability to prove the information-theoretic security (ITS) of the established keys. As a key establishment primitive, QKD however does not…

Cryptographic key exchange protocols traditionally rely on computational conjectures such as the hardness of prime factorisation to provide security against eavesdropping attacks. Remarkably, quantum key distribution protocols like the one…

Quantum key distribution (QKD) together with one time pad encoding can provide information-theoretical security for communication. Currently, though QKD has been widely deployed in many metropolitan fiber networks, its implementation in a…

Quantum Physics · Physics 2018-09-10 Qiang Zhang , Feihu Xu , Yu-Ao Chen , Cheng-Zhi Peng , Jian-Wei Pan

We prove the unconditional security of an entanglement-based quantum-key-distribution protocol using detectors that respond to multiple modes of light and cannot distinguish between one from two or more photons. Even with such practical…

Quantum Physics · Physics 2008-04-08 Masato Koashi , Yoritoshi Adachi , Takashi Yamamoto , Nobuyuki Imoto

Quantum Key Distribution (QKD) enables two distant users to exchange a secret key with information-theoretic security, based on the fundamental laws of quantum physics. While it is arguably the most mature application of quantum…

Quantum key distribution is among the foremost applications of quantum mechanics, both in terms of fundamental physics and as a technology on the brink of commercial deployment. Starting from principal schemes and initial proofs of…

Quantum Physics · Physics 2008-01-29 Wolfgang Mauerer , Wolfram Helwig , Christine Silberhorn

Device-independent quantum key distribution is the task of using uncharacterized quantum devices to establish a shared key between two users. If a protocol is secure regardless of the device behaviour, it can be used to generate a shared…

Quantum Physics · Physics 2013-01-01 Jonathan Barrett , Roger Colbeck , Adrian Kent

Quantum key distribution (QKD) can provide information theoretically secure key exchange even in the era of quantum computer. However, QKD requires the classical channel to be authenticated, and the current method is pre-sharing symmetric…

We analyse the distribution of secure keys using quantum cryptography based on the continuous variable degree of freedom of entangled photon pairs. We derive the information capacity of a scheme based on the spatial entanglement of photons…

Quantum Physics · Physics 2009-11-13 Lijian Zhang , Christine Silberhorn , Ian A. Walmsley

Quantum key distribution (QKD) allows Alice and Bob to share a secret key over an insecure channel with proven information-theoretic security against an adversary whose strategy is bounded only by the laws of physics. Composability-based…

Quantum Physics · Physics 2026-01-21 Kunal Dey , Reihaneh Safavi-Naini

This paper introduces a completely new approach to encryption based on group theoretic quantum framework. Quantum cryptography has essentially focused only on key distribution and proceeded with classical encryption algorithm with the…

Discrete Mathematics · Computer Science 2007-05-23 N. Srinivasan , C. Sanjeevakumar , L. Sudarsan , M. Kasi Rajan , R. Venkatesh

It is generally believed that unconditionally secure quantum bit commitment is impossible, due to widespread acceptance of an impossibility proof that utilizes quantum entaglement cheating. In this paper, we delineate how the impossibiliy…

Quantum Physics · Physics 2007-05-23 Horace P. Yuen

Quantum cryptography is arguably the fastest growing area in quantum information science. Novel theoretical protocols are designed on a regular basis, security proofs are constantly improving, and experiments are gradually moving from…

Provable entanglement has been shown to be a necessary precondition for unconditionally secure key generation in the context of quantum cryptographic protocols. We estimate the maximal threshold disturbance up to which the two legitimate…

Quantum Physics · Physics 2007-05-23 G. M. Nikolopoulos , A. Khalique , G. Alber

Privacy amplification is a necessary step in all quantum key distribution protocols, and error correction is needed in each except when signals of many photons are used in the key communication in quantum noise approach. No security…

Quantum Physics · Physics 2014-11-11 Horace Yuen

Device-independent quantum key distribution aims to provide key distribution schemes whose security is based on the laws of quantum physics but which does not require any assumptions about the internal working of the quantum devices used in…

Quantum Physics · Physics 2011-03-18 Lluis Masanes , Stefano Pironio , Antonio Acin