CHAOTIC DIGITAL ENCODING - AN APPROACH TO SECURE COMMUNICATION

A method for using chaos in the digital domain for secure communicatio ns is proposed. The method uses a nonlinear digital filter with finite precision (8 bits) in conjunction with its inverse filter to implemen t an encoder and a decoder, respectively. The nature of the encoder is such that it behaves in a quasi-chaotic fashion (since chaotic behavi or requires infinite precision), both with zero and nonzero input sequ ences. The determination of its quasi-chaotic behavior is based on QC- properties defined in the paper, which are proposed as a test for fini te state digital filters. At the very least, these properties suggest that the encoder possessing them will be of value in secure communicat ions applications. Variations on the encoding scheme are suggested tha t allow the potential for a wide range of applications, ranging from c ost-effective real-time systems to high security systems incorporating one or more ''keys.'' Simulation results as well as a mathematical an alysis are used to promote an understanding of the performance of the nonlinear encoder/decoder.