Date of Award

Fall 2004

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Yechiel J. Crispin

Committee Member

Habib Eslami

Committee Member

L.L. Narayanaswami

Abstract

The purpose of this thesis is to study the use of adaptive synchronization of chaos for secure communication. Several non-linear models were studied, the one-dimensional logistic map, two-dimensional coupled logistic map, three dimensional Lorenz systems with and without time delay. Numerical simulation using MATLAB was conducted. The Lorenz system with time delay was studied numerically as well as by testing an analog circuit and comparisons was made between them. It has been pointed out in many research papers that for low-dimensional chaotic processes, once intercepted, the information can be readily extracted, so the interest has been directed to higher dimensional chaotic system synchronization. The analog circuit gives a more accurate precise real time simulation.

The approach for secure communication utilizes the driver and driven synchronization of two identical chaotic systems. At the transmitter, information is added as a time varying parameter of the Lorenz system, and one of the state variables is transmitted through the public channel. This state variable is used to drive the receiver causing the two systems to synchronize in time. The driver system is used as the model reference for the adaptive controller to synchronize both the transmitter and the receiver system. The results of the Lorenz system are very conclusive both from the computer simulation and the analog circuits.

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