Safya Belghith

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Science and Numerical Simulations in February 2009. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Abstract In this comment, we analyze a(More)
In this paper, we propose to cryptanalyse an encryption algorithm which combines a DNA addition and a chaotic map to encrypt a gray scale image. Our contribution consists on, at first, demonstrating that the algorithm, as it is described, is non-invertible, which means that the receiver cannot decrypt the ciphered image even if he posses the secret key.(More)
In this paper, we propose to enhance a recently proposed image cryptosystem based on hyper-chaos. The updated version has been builded to resist against attacks made to break the original one and to make it faster. The modification touch on the two Boxes, P-Box and S-Box, which composed the original cryptosystem. Compared with classical encryption scheme,(More)
The paper proposes breaks for the permutation methods adopted in the chaos-based image cryptosystems. By a careful examination on the most chaotic image cryptosystems we can find that the permutation process constitute the main step or, in some cases, the only step to create the confusion. It can be applied on the pixels or on the pixel bits. A recently(More)
We propose an estimator for nonlinear systems with unmatched unknown inputs and under measurement noise. The estimator design is based on the combination of observer design for descriptor systems, sliding-modes theory and adaptive control. The estimation of the measurement noise is achieved thanks to the transformation of the original system into a singular(More)
In this paper a piecewise linear chaotic map (PWLCM) is used to build a new digital chaotic cryptosystem. The characteristics of PWLCM are very suitable for the design of encryption schemes. The implicit digital degradation problem of PWLCM has been eluded through the discretization of the phase space. The accuracy, efficiency and security of the proposed(More)
This chapter presents further investigations into the period-three route to chaos exhibited in the passive dynamic walking of the compass-gait biped robot as it goes down an inclined surface. This discovered kind of route in the passive bipedal locomotion was found to coexist with the conventional period-one passive hybrid limit cycle. The further analysis(More)
The planar passive compass-gait biped robot on sloped surfaces is the simplest model of legged walkers. It is a two-degrees-of-freedom impulsive mechanical system known to exhibit, in response to an increase in the slope angle of the walking surface, a sequence of period-doubling bifurcations leading to chaos before falling down at some critical slope(More)