9,528 research outputs found
Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption
Optical chaos is a topic of current research characterized by
high-dimensional nonlinearity which is attributed to the delay-induced
dynamics, high bandwidth and easy modular implementation of optical feedback.
In light of these facts, which adds enough confusion and diffusion properties
for secure communications, we explore the synchronization phenomena in
spatiotemporal semiconductor laser systems. The novel system is used in a
two-phase colored image encryption process. The high-dimensional chaotic
attractor generated by the system produces a completely randomized chaotic time
series, which is ideal in the secure encoding of messages. The scheme thus
illustrated is a two-phase encryption method, which provides sufficiently high
confusion and diffusion properties of chaotic cryptosystem employed with unique
data sets of processed chaotic sequences. In this novel method of cryptography,
the chaotic phase masks are represented as images using the chaotic sequences
as the elements of the image. The scheme drastically permutes the positions of
the picture elements. The next additional layer of security further alters the
statistical information of the original image to a great extent along the
three-color planes. The intermediate results during encryption demonstrate the
infeasibility for an unauthorized user to decipher the cipher image. Exhaustive
statistical tests conducted validate that the scheme is robust against noise
and resistant to common attacks due to the double shield of encryption and the
infinite dimensionality of the relevant system of partial differential
equations.Comment: 20 pages, 11 figures; Article in press, Optics Communications (2011
Quantum Key Distribution (QKD) and Commodity Security Protocols: Introduction and Integration
We present an overview of quantum key distribution (QKD), a secure key
exchange method based on the quantum laws of physics rather than computational
complexity. We also provide an overview of the two most widely used commodity
security protocols, IPsec and TLS. Pursuing a key exchange model, we propose
how QKD could be integrated into these security applications. For such a QKD
integration we propose a support layer that provides a set of common QKD
services between the QKD protocol and the security applicationsComment: 12Page
Clock synchronization by remote detection of correlated photon pairs
We present an algorithm to detect the time and frequency difference of
independent clocks based on observation of time-correlated photon pairs. This
enables remote coincidence identification in entanglement-based quantum key
distribution schemes without dedicated coincidence hardware, pulsed sources
with a timing structure or very stable reference clocks. We discuss the method
for typical operating conditions, and show that the requirement in reference
clock accuracy can be relaxed by about 5 orders of magnitude in comparison with
previous schemes.Comment: 14 pages, 6 figure
Experimental quantum key distribution with simulated ground-to-satellite photon losses and processing limitations
Quantum key distribution (QKD) has the potential to improve communications
security by offering cryptographic keys whose security relies on the
fundamental properties of quantum physics. The use of a trusted quantum
receiver on an orbiting satellite is the most practical near-term solution to
the challenge of achieving long-distance (global-scale) QKD, currently limited
to a few hundred kilometers on the ground. This scenario presents unique
challenges, such as high photon losses and restricted classical data
transmission and processing power due to the limitations of a typical satellite
platform. Here we demonstrate the feasibility of such a system by implementing
a QKD protocol, with optical transmission and full post-processing, in the
high-loss regime using minimized computing hardware at the receiver. Employing
weak coherent pulses with decoy states, we demonstrate the production of secure
key bits at up to 56.5 dB of photon loss. We further illustrate the feasibility
of a satellite uplink by generating secure key while experimentally emulating
the varying channel losses predicted for realistic low-Earth-orbit satellite
passes at 600 km altitude. With a 76 MHz source and including finite-size
analysis, we extract 3374 bits of secure key from the best pass. We also
illustrate the potential benefit of combining multiple passes together: while
one suboptimal "upper-quartile" pass produces no finite-sized key with our
source, the combination of three such passes allows us to extract 165 bits of
secure key. Alternatively, we find that by increasing the signal rate to 300
MHz it would be possible to extract 21570 bits of secure finite-sized key in
just a single upper-quartile pass.Comment: 12 pages, 7 figures, 2 table
QuNetSim: A Software Framework for Quantum Networks
As quantum internet technologies develop, the need for simulation software
and education for quantum internet rises. QuNetSim aims to fill this need.
QuNetSim is a Python software framework that can be used to simulate quantum
networks up to the network layer. The goal of QuNetSim is to make it easier to
investigate and test quantum networking protocols over various quantum network
configurations and parameters. The framework incorporates many known quantum
network protocols so that users can quickly build simulations and beginners can
easily learn to implement their own quantum networking protocols.Comment: 11 pages, 6 figure
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