1,053 research outputs found
Low-Dimensional Reconciliation for Continuous-Variable Quantum Key Distribution
We propose an efficient logical layer-based reconciliation method for
continuous-variable quantum key distribution (CVQKD) to extract binary
information from correlated Gaussian variables. We demonstrate that by
operating on the raw-data level, the noise of the quantum channel can be
corrected in the low-dimensional (scalar) space and the reconciliation can be
extended to arbitrary dimensions. The CVQKD systems allow an unconditionally
secret communication over standard telecommunication networks. To exploit the
real potential of CVQKD a robust reconciliation technique is needed. It is
currently unavailable, which makes it impossible to reach the real performance
of the CVQKD protocols. The reconciliation is a post-processing step separated
from the transmission of quantum states, which is aimed to derive the secret
key from the raw data. The reconciliation process of correlated Gaussian
variables is a complex problem that requires either tomography in the physical
layer that is intractable in a practical scenario, or high-cost calculations in
the multidimensional spherical space with strict dimensional limitations. To
avoid these issues we define the low-dimensional reconciliation. We prove that
the error probability of one-dimensional reconciliation is zero in any
practical CVQKD scenario, and provides unconditional security. The results
allow to significantly improve the currently available key rates and
transmission distances of CVQKD.Comment: 43 pages, Journal-ref: Appl. Sci. (accepted
Modeling, Simulation, and Analysis of a Decoy State Enabled Quantum Key Distribution System
Quantum Key Distribution (QKD) is an emerging technology which uses the principles of quantum mechanics to provide unconditionally secure key distribution. QKD systems are unique in their ability to detect an eavesdropper\u27s presence and are being marketed for applications where high levels of secrecy are required such as banking, government, and military environments. QKD systems are composed of electrical, optical, and electrooptical components. Their design requires expertise across multiple disciplines including computer science, computer engineering, electrical engineering, information theory, optical physics, and quantum physics. This multidisciplinary nature makes QKD an ideal candidate for study using Model Based Systems Engineering (MBSE) Processes, Methods, and Tools (PMTs). The primary research goal is to gain understanding of the operation and performance of the QKD decoy state protocol through the use of MBSE PMTs. The main research contributions include development of a decoy state model, validation of the this protocol in a QKD system model implementation, and confirmation that application of MBSE PMTs are critical to the understanding and analysis of complex systems. This work presents the first known application of MBSE PMTs to analyze a QKD system and provides utility to system developers, designers and analysts who seek to quantify performance and security
Security of Quantum Key Distribution
We propose various new techniques in quantum information theory, including a
de Finetti style representation theorem for finite symmetric quantum states. As
an application, we give a proof for the security of quantum key distribution
which applies to arbitrary protocols.Comment: PhD thesis; index adde
Analysis of BCNS and Newhope Key-exchange Protocols
Lattice-based cryptographic primitives are believed to offer resilience against attacks by quantum computers. Following increasing interest from both companies and government agencies in building quantum computers, a number of works have proposed instantiations of practical post-quantum key-exchange protocols based on hard problems in lattices, mainly based on the Ring Learning With Errors (R-LWE) problem.
In this work we present an analysis of Ring-LWE based key-exchange mechanisms and compare two implementations of Ring-LWE based key-exchange protocol: BCNS and NewHope. This is important as NewHope protocol implementation outperforms state-of-the art elliptic curve based Diffie-Hellman key-exchange X25519, thus showing that using quantum safe key-exchange is not only a viable option but also a faster one. Specifically, this thesis compares different reconciliation methods, parameter choices, noise sampling algorithms and performance
Quantum Information with Continuous Variable systems
This thesis deals with the study of quantum communication protocols with
Continuous Variable (CV) systems. Continuous Variable systems are those
described by canonical conjugated coordinates x and p endowed with infinite
dimensional Hilbert spaces, thus involving a complex mathematical structure. A
special class of CV states, are the so-called Gaussian states. With them, it
has been possible to implement certain quantum tasks as quantum teleportation,
quantum cryptography and quantum computation with fantastic experimental
success. The importance of Gaussian states is two-fold; firstly, its structural
mathematical description makes them much more amenable than any other CV
system. Secondly, its production, manipulation and detection with current
optical technology can be done with a very high degree of accuracy and control.
Nevertheless, it is known that in spite of their exceptional role within the
space of all Continuous Variable states, in fact, Gaussian states are not
always the best candidates to perform quantum information tasks. Thus
non-Gaussian states emerge as potentially good candidates for communication and
computation purposes.Comment: PhD Thesis in Universitat Autonoma de Barcelona. Published by the
Lambert Academic Publishing (LAP) on March 18, 2011. ISBN-13:
978-3-8443-1948-
The Effect of Eavesdropper's Statistics in Experimental Wireless Secret-Key Generation
This paper investigates the role of the eavesdropper's statistics in the
implementation of a practical secret-key generation system. We carefully
conduct the information-theoretic analysis of a secret-key generation system
from wireless channel gains measured with software-defined radios. In
particular, we show that it is inaccurate to assume that the eavesdropper gets
no information because of decorrelation with distance. We also provide a bound
for the achievable secret-key rate in the finite key-length regime that takes
into account the presence of correlated eavesdropper's observations. We
evaluate this bound with our experimental gain measurements to show that
operating with a finite number of samples incurs a loss in secret-key rate on
the order of 20%.Comment: Submitted to the IEEE Transactions on Information Forensics and
Securit
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