10,515 research outputs found
Secure Communication using Compound Signal from Generalized Synchronizable Chaotic Systems
By considering generalized synchronizable chaotic systems, the
drive-auxiliary system variables are combined suitably using encryption key
functions to obtain a compound chaotic signal. An appropriate feedback loop is
constructed in the response-auxiliary system to achieve synchronization among
the variables of the drive-auxiliary and response-auxiliary systems. We apply
this approach to transmit analog and digital information signals in which the
quality of the recovered signal is higher and the encoding is more secure.Comment: 7 pages (7 figures) RevTeX, Please e-mail Lakshmanan for figures,
submitted to Phys. Lett. A (E-mail: [email protected]
Chaos-based communication scheme using proportional and proportional-integral observers
In this paper, we propose a new chaos-based communication scheme using the observers. The novelty lies in the masking procedure that is employed to hide the confidential information using the chaotic oscillator. We use a combination of the addition and inclusion methods to mask the information. The performance of two observers, the proportional observer (P-observer) and the proportional integral observer (PI-observer) is compared that are employed as receivers for the proposed communication scheme. We show that the P-observer is not suitable scheme since it imposes unpractical constraints on the messages to be transmitted. On the other hand, we show that the PI-observer is the better solution because it allows greater flexibility in choosing the gains of the observer and does not impose any unpractical restrictions on the message
Complex Dynamics and Synchronization of Delayed-Feedback Nonlinear Oscillators
We describe a flexible and modular delayed-feedback nonlinear oscillator that
is capable of generating a wide range of dynamical behaviours, from periodic
oscillations to high-dimensional chaos. The oscillator uses electrooptic
modulation and fibre-optic transmission, with feedback and filtering
implemented through real-time digital-signal processing. We consider two such
oscillators that are coupled to one another, and we identify the conditions
under which they will synchronize. By examining the rates of divergence or
convergence between two coupled oscillators, we quantify the maximum Lyapunov
exponents or transverse Lyapunov exponents of the system, and we present an
experimental method to determine these rates that does not require a
mathematical model of the system. Finally, we demonstrate a new adaptive
control method that keeps two oscillators synchronized even when the coupling
between them is changing unpredictably.Comment: 24 pages, 13 figures. To appear in Phil. Trans. R. Soc. A (special
theme issue to accompany 2009 International Workshop on Delayed Complex
Systems
Secure Digital Signal Transmission by Multistep Parameter Modulation and Alternative Driving of Transmitter Variables
The idea of secure communication of digital signals via chaos synchronization
has been plagued by the possibility of attractor reconstruction by
eavesdroppers as pointed out by Perez and Cerdeira. In this Letter, we wish to
present a very simple mechanism by which this problem can be overcome, wherein
the signal is transmitted via a multistep parameter modulation combined with
alternative driving of different transmitter variables, which makes the
attractor reconstruction impossible. The method is illustrated by means of the
Lorenz system and Chua's circuit as examples.Comment: 15 pages, RevTeX, 6 eps figures, To appear in Int. J. Bifurcation and
Chaos (July 2001
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