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Cryptology Column  25 Years of Quantum Cryptography
, 1996
"... The fates of SIGACT News and Quantum Cryptography are inseparably entangled. The exact date of Stephen Wiesner's invention of "conjugate coding" is unknown but it cannot be far from April 1969, when the premier issue of SIGACT Newsor rather SICACT News as it was known at the time ..."
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The fates of SIGACT News and Quantum Cryptography are inseparably entangled. The exact date of Stephen Wiesner's invention of "conjugate coding" is unknown but it cannot be far from April 1969, when the premier issue of SIGACT Newsor rather SICACT News as it was known at the timecame out. Much later, it was in SIGACT News that Wiesner's paper finally appeared [74] in the wake of the first author's early collaboration with Charles H. Bennett [7]. It was also in SIGACT News that the original experimental demonstration for quantum key distribution was announced for the first time [6] and that a thorough bibliography was published [19]. Finally, it was in SIGACT News that Doug Wiedemann chose to publish his discovery when he reinvented quantum key distribution in 1987, unaware of all previous work but Wiesner's [73, 5]. Most of the first decade of the history of quant
Densecoding attack on threeParty quantum key distribution protocols
 IEEE J. Quant. Electron
, 2011
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Demonstration of active quantum key distribution network
 Optics and Photonics 06, Proc. SPIE 6305, 630506
, 2006
"... We previously demonstrated a high speed, point to point, quantum key distribution (QKD) system with polarization coding over a fiber link, in which the resulting cryptographic keys were used for onetime pad encryption of real time video signals. In this work, we extend the technology to a threenod ..."
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We previously demonstrated a high speed, point to point, quantum key distribution (QKD) system with polarization coding over a fiber link, in which the resulting cryptographic keys were used for onetime pad encryption of real time video signals. In this work, we extend the technology to a threenode active QKD network one Alice and two Bobs. A QKD network allows multiple users to generate and share secure quantum keys. In comparison with a passive QKD network, nodes in an active network can actively select a destination as a communication partner and therefore, its siftedkey rate can remain at a speed almost as high as that in the pointtopoint QKD. We demonstrate our threenode QKD network in the context of a QKD secured realtime video surveillance system. In principle, the technologies for the threenode network are extendable to multinode networks easily. In this paper, we report our experiments, including the techniques for timing alignment and polarization recovery during switching, and discuss the network architecture and its expandability to multinode networks.
HighSpeed Quantum Key Distribution System for Optical Fiber networks in campus and metro areas
 SPIE Quantum Communications and Quantum Imaging VI, Proc. SPIE
"... Complete highspeed quantum key distribution (QKD) systems over fiber networks for campus and metro areas have been developed at NIST. The systems include an 850nm QKD system for a campus network, a 1310nm QKD system for metro networks, and a 3user QKD network and network manager. In this paper w ..."
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Complete highspeed quantum key distribution (QKD) systems over fiber networks for campus and metro areas have been developed at NIST. The systems include an 850nm QKD system for a campus network, a 1310nm QKD system for metro networks, and a 3user QKD network and network manager. In this paper we describe the key techniques used to implement these systems, including polarization recovery, noise reduction, frequency upconversion detection based on PPLN waveguide, custom highspeed data handling and network management. A QKDsecured video surveillance system has been used to experimentally demonstrate these systems.
ACHIEVING UNCONDITIONAL SECURITY BY QUANTUM CRYPTOGRAPHY
"... Classical cryptography algorithms are based on mathematical functions. The robustness of a given cryptosystem is based essentially on the secrecy of its (private) key and the difficulty with which the inverse of its oneway function(s) can be calculated. Unfortunately, there is no mathematical proof ..."
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Classical cryptography algorithms are based on mathematical functions. The robustness of a given cryptosystem is based essentially on the secrecy of its (private) key and the difficulty with which the inverse of its oneway function(s) can be calculated. Unfortunately, there is no mathematical proof that will establish whether it is not possible to find the inverse of a given oneway function. Since few years ago, the progress of quantum physics allowed mastering photons which can be used for informational ends and these technological progresses can also be applied to cryptography (quantum cryptography). Quantum cryptography or Quantum Key Distribution (QKD) is a method for sharing secret keys, whose security can be formally demonstrated. It aims at exploiting the laws of quantum physics in order to carry out a cryptographic task. Its legitimate users can detect eavesdropping, regardless of the technology which the spy may have. In this study, we present quantum cryptosystems as a tool to attain the unconditional security. We also describe the well known protocols used in the field of quantum cryptography. Keywords:quantum cryptogarphy,quantum key distribtuion, uncondtional security.
1 Enhanced Quantum Key Distribution Protocols
"... Fourstate quantum key distribution (QKD) protocol BB84 [1] and twostate QKD protocol B92 [2] can let Alice and Bob share the secret key with idealized maximum efficiencies 50 % and 25 % over quantum channel, respectively. However, for these two polarizationbased systems, the polarization states n ..."
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Fourstate quantum key distribution (QKD) protocol BB84 [1] and twostate QKD protocol B92 [2] can let Alice and Bob share the secret key with idealized maximum efficiencies 50 % and 25 % over quantum channel, respectively. However, for these two polarizationbased systems, the polarization states need to be maintained stable and against the noise of photon over a long distance optical fiber. Due to the alignment of polarization and the need of apparatus, the complexity of a fourstate protocol is greater than that of twostate protocol. We herein use average number of polarization states in a QKD protocol as the complexity order. In this paper, we propose two enhanced QKD protocols. One is to enhance the idealized maximum efficiency to 28.6 % with the average complexity order 2, and the other has the efficiency 42.9 % and the average complexity order 2.86.
Mediated SemiQuantum Key Distribution
, 2014
"... In this paper, we design a new quantum key distribution protocol, allowing two limited semiquantum or “classical ” users to establish a shared secret key with the help of a fully quantum server. A semiquantum user can only prepare and measure qubits in the computational basis and so must rely on ..."
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In this paper, we design a new quantum key distribution protocol, allowing two limited semiquantum or “classical ” users to establish a shared secret key with the help of a fully quantum server. A semiquantum user can only prepare and measure qubits in the computational basis and so must rely on this quantum server to produce qubits in alternative bases and also to perform alternative measurements. However, we assume that the sever is untrusted and we prove the unconditional security of our protocol even in the worst case: when this quantum server is an allpowerful adversary. We also compute a lower bound of the key rate of our protocol, in the asymptotic scenario, as a function of the observed error rate in the channel allowing us to compute the maximally tolerated error of our protocol. Our results show that a semiquantum protocol may hold similar security to a fully quantum one. 1