143 research outputs found
Cryptography and Its Applications in Information Security
Nowadays, mankind is living in a cyber world. Modern technologies involve fast communication links between potentially billions of devices through complex networks (satellite, mobile phone, Internet, Internet of Things (IoT), etc.). The main concern posed by these entangled complex networks is their protection against passive and active attacks that could compromise public security (sabotage, espionage, cyber-terrorism) and privacy. This Special Issue âCryptography and Its Applications in Information Securityâ addresses the range of problems related to the security of information in networks and multimedia communications and to bring together researchers, practitioners, and industrials interested by such questions. It consists of eight peer-reviewed papers, however easily understandable, that cover a range of subjects and applications related security of information
From Chaos to Pseudorandomness: A Case Study on the 2-D Coupled Map Lattice
Applying the chaos theory for secure digital communications is promising and it is well acknowledged that in such applications the underlying chaotic systems should be carefully chosen. However, the requirements imposed on the chaotic systems are usually heuristic, without theoretic guarantee for the resultant communication scheme. Among all the primitives for secure communications, it is well accepted that (pseudo) random numbers are most essential. Taking the well-studied 2-D coupled map lattice (2D CML) as an example, this article performs a theoretical study toward pseudorandom number generation with the 2D CML. In so doing, an analytical expression of the Lyapunov exponent (LE) spectrum of the 2D CML is first derived. Using the LEs, one can configure system parameters to ensure the 2D CML only exhibits complex dynamic behavior, and then collect pseudorandom numbers from the system orbits. Moreover, based on the observation that least significant bit distributes more evenly in the (pseudo) random distribution, an extraction algorithm E is developed with the property that when applied to the orbits of the 2D CML, it can squeeze uniform bits. In implementation, if fixed-point arithmetic is used in binary format with a precision of z bits after the radix point, E can ensure that the deviation of the squeezed bits is bounded by 2(-z) . Further simulation results demonstrate that the new method not only guides the 2D CML model to exhibit complex dynamic behavior but also generates uniformly distributed independent bits with good efficiency. In particular, the squeezed pseudorandom bits can pass both NIST 800-22 and TestU01 test suites in various settings. This study thereby provides a theoretical basis for effectively applying the 2D CML to secure communications
A Novel Diffusion-Permutation Image Encryption Scheme Based on Spatiotemporal Chaos
The spatiotemporal chaos possesses better properties than simple chaotic system, which has attracted more and more attention by the researchers in the image encryption field. This paper presents a novel image encryption scheme based on spatiotemporal chaos. The algorithm uses the spatiotemporal chaos to diffuse plain image and an Arnold map shuffle the positions of pixels. Test results and security analysis not only show that the scheme is characteristic of excellent sensitivity to the original image and keys, large secret key space and high expansibility, but also has excellent effective encryption and strong anti-attacking performance
Predictability: a way to characterize Complexity
Different aspects of the predictability problem in dynamical systems are
reviewed. The deep relation among Lyapunov exponents, Kolmogorov-Sinai entropy,
Shannon entropy and algorithmic complexity is discussed. In particular, we
emphasize how a characterization of the unpredictability of a system gives a
measure of its complexity. Adopting this point of view, we review some
developments in the characterization of the predictability of systems showing
different kind of complexity: from low-dimensional systems to high-dimensional
ones with spatio-temporal chaos and to fully developed turbulence. A special
attention is devoted to finite-time and finite-resolution effects on
predictability, which can be accounted with suitable generalization of the
standard indicators. The problems involved in systems with intrinsic randomness
is discussed, with emphasis on the important problems of distinguishing chaos
from noise and of modeling the system. The characterization of irregular
behavior in systems with discrete phase space is also considered.Comment: 142 Latex pgs. 41 included eps figures, submitted to Physics Reports.
Related information at this http://axtnt2.phys.uniroma1.i
Lyapunov Exponents for Temporal Networks
By interpreting a temporal network as a trajectory of a latent graph
dynamical system, we introduce the concept of dynamical instability of a
temporal network, and construct a measure to estimate the network Maximum
Lyapunov Exponent (nMLE) of a temporal network trajectory. Extending
conventional algorithmic methods from nonlinear time-series analysis to
networks, we show how to quantify sensitive dependence on initial conditions,
and estimate the nMLE directly from a single network trajectory. We validate
our method for a range of synthetic generative network models displaying low
and high dimensional chaos, and finally discuss potential applications
An Adaptive Image Encryption Scheme Guided by Fuzzy Models
A new image encryption scheme using the advanced encryption standard (AES), a
chaotic map, a genetic operator, and a fuzzy inference system is proposed in
this paper. In this work, plain images were used as input, and the required
security level was achieved. Security criteria were computed after running a
proposed encryption process. Then an adaptive fuzzy system decided whether to
repeat the encryption process, terminate it, or run the next stage based on the
achieved results and user demand. The SHA-512 hash function was employed to
increase key sensitivity. Security analysis was conducted to evaluate the
security of the proposed scheme, which showed it had high security and all the
criteria necessary for a good and efficient encryption algorithm were met.
Simulation results and the comparison of similar works showed the proposed
encryptor had a pseudo-noise output and was strongly dependent upon the
changing key and plain image.Comment: Iranian Journal of Fuzzy Systems (2023
Discovering Functional Communities in Dynamical Networks
Many networks are important because they are substrates for dynamical
systems, and their pattern of functional connectivity can itself be dynamic --
they can functionally reorganize, even if their underlying anatomical structure
remains fixed. However, the recent rapid progress in discovering the community
structure of networks has overwhelmingly focused on that constant anatomical
connectivity. In this paper, we lay out the problem of discovering_functional
communities_, and describe an approach to doing so. This method combines recent
work on measuring information sharing across stochastic networks with an
existing and successful community-discovery algorithm for weighted networks. We
illustrate it with an application to a large biophysical model of the
transition from beta to gamma rhythms in the hippocampus.Comment: 18 pages, 4 figures, Springer "Lecture Notes in Computer Science"
style. Forthcoming in the proceedings of the workshop "Statistical Network
Analysis: Models, Issues and New Directions", at ICML 2006. Version 2: small
clarifications, typo corrections, added referenc
Complexity Measures from Interaction Structures
We evaluate new complexity measures on the symbolic dynamics of coupled tent
maps and cellular automata. These measures quantify complexity in terms of
-th order statistical dependencies that cannot be reduced to interactions
between units. We demonstrate that these measures are able to identify
complex dynamical regimes.Comment: 11 pages, figures improved, minor changes to the tex
Probabilistic and thermodynamic aspects of dynamical systems
The probabilistic approach to dynamical systems giving rise to irreversible behavior at the macroscopic, mesoscopic, and microscopic levels of description is outlined. Signatures of the complexity of the underlying dynamics on the spectral properties of the Liouville, Frobenius-Perron, and Fokker-Planck operators are identified. Entropy and entropy production-like quantities are introduced and the connection between their properties in nonequilibrium steady states and the characteristics of the dynamics in phase space are explored.info:eu-repo/semantics/publishe
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