4,947 research outputs found
Breaking a Chaotic Cryptographic Scheme Based on Composition Maps
Recently, a chaotic cryptographic scheme based on composition maps was
proposed. This paper studies the security of the scheme and reports the
following findings: 1) the scheme can be broken by a differential attack with
chosen-plaintext, where is the size of
plaintext and is the number of different elements in plain-text; 2) the
scheme is not sensitive to the changes of plaintext; 3) the two composition
maps do not work well as a secure and efficient random number source.Comment: 9 pages, 7 figure
Derivation of diagnostic models based on formalized process knowledge
© IFAC.Industrial systems are vulnerable to faults. Early and accurate detection and diagnosis in production systems can minimize down-time, increase the safety of the plant operation, and reduce manufacturing costs. Knowledge- and model-based approaches to automated fault detection and diagnosis have been demonstrated to be suitable for fault cause analysis within a broad range of industrial processes and research case studies. However, the implementation of these methods demands a complex and error-prone development phase, especially due to the extensive efforts required during the derivation of models and their respective validation. In an effort to reduce such modeling complexity, this paper presents a structured causal modeling approach to supporting the derivation of diagnostic models based on formalized process knowledge. The method described herein exploits the Formalized Process Description Guideline VDI/VDE 3682 to establish causal relations among key-process variables, develops an extension of the Signed Digraph model combined with the use of fuzzy set theory to allow more accurate causality descriptions, and proposes a representation of the resulting diagnostic model in CAEX/AutomationML targeting dynamic data access, portability, and seamless information exchange
Non-Abelian Vortices on the Torus
We study periodic arrays of non-Abelian vortices in an
gauge theory with flavors of fundamental matter multiplets. We carefully
discuss the corresponding twisted boundary conditions on the torus and propose
an ansatz to solve the first order Bogomolnyi equations which we find by
looking to a bound of the energy. We solve the equations numerically and
construct explicit vortex solutions
Breaking an image encryption algorithm based on chaos
Recently, a chaos-based image encryption algorithm called MCKBA (Modified
Chaotic-Key Based Algorithm) was proposed. This paper analyzes the security of
MCKBA and finds that it can be broken with a differential attack, which
requires only four chosen plain-images. Performance of the attack is verified
by experimental results. In addition, some defects of MCKBA, including
insensitivity with respect to changes of plain-image/secret key, are reported.Comment: 10 pages, 4 figure
Integrability in Theories with Local U(1) Gauge Symmetry
Using a recently developed method, based on a generalization of the zero
curvature representation of Zakharov and Shabat, we study the integrability
structure in the Abelian Higgs model. It is shown that the model contains
integrable sectors, where integrability is understood as the existence of
infinitely many conserved currents. In particular, a gauge invariant
description of the weak and strong integrable sectors is provided. The
pertinent integrability conditions are given by a U(1) generalization of the
standard strong and weak constraints for models with two dimensional target
space. The Bogomolny sector is discussed, as well, and we find that each
Bogomolny configuration supports infinitely many conserved currents. Finally,
other models with U(1) gauge symmetry are investigated.Comment: corrected typos, version accepted in J. Phys.
Adjoint modes as probes of gauge field structure
We show how zero-modes and quasi-zero-modes of the Dirac operator in the
adjoint representation can be used to construct an estimate of the action
density distribution of a pure gauge field theory, which is less sensitive to
the ultraviolet fluctuations of the field. This can be used to trace the
topological structures present in the vacuum. The construction relies on the
special properties satisfied by the supersymmetric zero-modes.Comment: Latex file. 29 pages and 12 figure
Expansion for the solutions of the Bogomolny equations on the torus
We show that the solutions of the Bogomolny equations for the Abelian Higgs
model on a two-dimensional torus, can be expanded in powers of a quantity
epsilon measuring the departure of the area from the critical area. This allows
a precise determination of the shape of the solutions for all magnetic fluxes
and arbitrary position of the Higgs field zeroes. The expansion is carried out
to 51 orders for a couple of representative cases, including the unit flux
case. We analyse the behaviour of the expansion in the limit of large areas, in
which case the solutions approach those on the plane. Our results suggest
convergence all the way up to infinite area.Comment: 26 pages, 8 figures, slightly revised version as published in JHE
On the security of a new image encryption scheme based on chaotic map lattices
This paper reports a detailed cryptanalysis of a recently proposed encryption
scheme based on the logistic map. Some problems are emphasized concerning the
key space definition and the implementation of the cryptosystem using
floating-point operations. It is also shown how it is possible to reduce
considerably the key space through a ciphertext-only attack. Moreover, a timing
attack allows the estimation of part of the key due to the existent
relationship between this part of the key and the encryption/decryption time.
As a result, the main features of the cryptosystem do not satisfy the demands
of secure communications. Some hints are offered to improve the cryptosystem
under study according to those requirements.Comment: 8 pages, 8 Figure
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