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Abstract
the chaos theory as a behavior of certain nonlinear application in cryptography. It introduces a developed to attack the chaotic cryptosystems, which are classifIed into three techniques: • switching, and modulation. The objective of attacking is to predict the n key, and use it to decrypt the encrypted messages in order to recover the
1: ”’on, The developed method attempts to recover the cipher key without a priori
e of a message signal. The developed method is applied on the modulation
provides a very interesting property ”Sensitive Dependence on Initial ,
su, That a small variation in one parameter value will grow exponentially, and
of the signal will be changed. Thus, in order to use a chaotic generator in a i’,cation system, the parameters of the transmitter must be identical to the of the receiver. The analogue chaotic cryptosystems suffer from this property,
, physical components accuracy causes a mismatch between the transmitter and er, The accuracy of the components is affected by many factors: life time, • and tolerance of industry process. In addition, some continuous time chaotic cannot be implemented using physical circuit. One solution to this problem is g the analogue generator into a digital generator to overcome the problem of
~~esis, two developed methods have been presented. The first method is based tion between hardware and software to overcome the parameter sensitivity ic generators. The software is used to simulate the analogue generator to
.•. ’
”tal signals, followed by a Data Acquisition Card to convert it to analogue
second method is a hardware implementation. In this method, a moditied chaotic generators were developed. These generators are realized using
,mable Gate Array (FPGA). A comparison has been made between the implementation methods and the results were nearly identical.