3,778 research outputs found
Trusted Noise in Continuous-Variable Quantum Key Distribution: a Threat and a Defense
We address the role of the phase-insensitive trusted preparation and
detection noise in the security of a continuous-variable quantum key
distribution, considering the Gaussian protocols on the basis of coherent and
squeezed states and studying them in the conditions of Gaussian lossy and noisy
channels. The influence of such a noise on the security of Gaussian quantum
cryptography can be crucial, even despite the fact that a noise is trusted, due
to a strongly nonlinear behavior of the quantum entropies involved in the
security analysis. We recapitulate the known effect of the preparation noise in
both direct and reverse-reconciliation protocols, as well as the detection
noise in the reverse-reconciliation scenario. As a new result, we show the
negative role of the trusted detection noise in the direct-reconciliation
scheme. We also describe the role of the trusted preparation or detection noise
added at the reference side of the protocols in improving the robustness of the
protocols to the channel noise, confirming the positive effect for the
coherent-state reverse-reconciliation protocol. Finally, we address the
combined effect of trusted noise added both in the source and the detector.Comment: 25 pages, 9 figure
Creation of backdoors in quantum communications via laser damage
Practical quantum communication (QC) protocols are assumed to be secure
provided implemented devices are properly characterized and all known side
channels are closed. We show that this is not always true. We demonstrate a
laser-damage attack capable of modifying device behaviour on-demand. We test it
on two practical QC systems for key distribution and coin-tossing, and show
that newly created deviations lead to side channels. This reveals that laser
damage is a potential security risk to existing QC systems, and necessitates
their testing to guarantee security.Comment: Changed the title to match the journal version. 9 pages, 5 figure
Distributing Secret Keys with Quantum Continuous Variables: Principle, Security and Implementations
The ability to distribute secret keys between two parties with
information-theoretic security, that is, regardless of the capacities of a
malevolent eavesdropper, is one of the most celebrated results in the field of
quantum information processing and communication. Indeed, quantum key
distribution illustrates the power of encoding information on the quantum
properties of light and has far reaching implications in high-security
applications. Today, quantum key distribution systems operate in real-world
conditions and are commercially available. As with most quantum information
protocols, quantum key distribution was first designed for qubits, the
individual quanta of information. However, the use of quantum continuous
variables for this task presents important advantages with respect to qubit
based protocols, in particular from a practical point of view, since it allows
for simple implementations that require only standard telecommunication
technology. In this review article, we describe the principle of
continuous-variable quantum key distribution, focusing in particular on
protocols based on coherent states. We discuss the security of these protocols
and report on the state-of-the-art in experimental implementations, including
the issue of side-channel attacks. We conclude with promising perspectives in
this research field.Comment: 21 pages, 2 figures, 1 tabl
Quantum cryptography: key distribution and beyond
Uniquely among the sciences, quantum cryptography has driven both
foundational research as well as practical real-life applications. We review
the progress of quantum cryptography in the last decade, covering quantum key
distribution and other applications.Comment: It's a review on quantum cryptography and it is not restricted to QK
Floodlight quantum key distribution: Demonstrating a framework for high-rate secure communication
Floodlight quantum key distribution (FL-QKD) is a radically different QKD paradigm that can achieve gigabit-per-second secret-key rates over metropolitan area distances without multiplexing [Q. Zhuang et al., Phys. Rev. A 94, 012322 (2016)]. It is a two-way protocol that transmits many photons per bit duration and employs a high-gain optical amplifier, neither of which can be utilized by existing QKD protocols, to mitigate channel loss. FL-QKD uses an optical bandwidth that is substantially larger than the modulation rate and performs decoding with a unique broadband homodyne receiver. Essential to FL-QKD is Alice's injection of photons from a photon-pair source—in addition to the light used for key generation—into the light she sends to Bob. This injection enables Alice and Bob to quantify Eve's intrusion and thus secure FL-QKD against collective attacks. Our proof-of-concept experiment included 10 dB propagation loss—equivalent to 50 km of low-loss fiber—and achieved a 55 Mbit/s secret-key rate (SKR) for a 100 Mbit/s modulation rate, as compared to the state-of-the-art system's 1 Mbit/s SKR for a 1 Gbit/s modulation rate [M. Lucamarini et al., Opt. Express 21, 24550 (2013)], representing ∼500-fold and ∼50 fold improvements in secret-key efficiency (bits per channel use) and SKR (bits per second), respectively.United States. Office of Naval Research (Grant N00014-13-1-0774)United States. Air Force Office of Scientific Research (Grant FA9550-14-1-0052)United States. Army Research Office (United States. Defense Advanced Research Projects Agency. Quiness Program. Grant W31P4Q-12-1-0019)United States. Office of Naval Research. Defense University Research Instrumentation Program (Grant N00014-14-1-0808
Controlling single-photon detector ID210 with bright light
We experimentally demonstrate that a single-photon detector ID210
commercially available from ID Quantique is vulnerable to blinding and can be
fully controlled by bright illumination. In quantum key distribution, this
vulnerability can be exploited by an eavesdropper to perform a faked-state
attack giving her full knowledge of the key without being noticed. We consider
the attack on standard BB84 protocol and a subcarrier-wave scheme, and outline
a possible countermeasure.Comment: 6 pages, 5 figure
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