chaos shift keying encryption system using chaos

chaos shift keying encryption system using chaos - IEEE...

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IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 37, NO. 7, JULY 2001 849 Chaos Shift Keying with an Optoelectronic Encryption System Using Chaos in Wavelength J.-B. Cuenot, L. Larger, J.-P. Goedgebuer, and William T. Rhodes Abstract— A chaos shift-keying modulation scheme in which the transmitter and the receiver are nonlinear time-delayed feedback systems is described. The change in the chaotic dynamics is dis- cussed when different parameters are used to encode digital sig- nals. The time-delay parameter is shown to assure the best condi- tions for data recovery. Index Terms— Chaos, communication system security, cryptog- raphy, delay systems, nonlinear oscillators, optical communica- tion, synchronization. I. INTRODUCTION A LONG with the development of optical telecommuni- cations systems has come an interest in secure optical transmissions and in optoelectronics techniques for signal en- cryption. Several optoelectronics systems have been proposed that exploit fast chaotic dynamics as a possible alternative to classical encryption techniques based on numerical algorithms. The first schemes proposed relied on signal masking: a small amplitude information signal is hidden by a large-amplitude noise-like chaotic signal. Optical systems have been reported theoretically [1], [2] and experimentally from Nd : YAG lasers [3], erbium-doped fiber lasers [4]–[7], and semiconductor lasers [8]–[12]. With such schemes, signal encoding is performed through the continuous modulation of a dynamical variable of a chaotic oscillator; decoding is achieved by synchronizing a chaotic receiver to the chaotic transmitter. A more sophisticated technique uses chaos shift-keying (CSK), e.g., with a Chua electronic circuit, as described by Dedieu [13], Parlitz [14], and Pinkney [15], or with a Lorenz-based electronic circuit, as described by Cuomo [16]. Other optoelectronic-based schemes have been reported by Celka [17] (using a Mach–Zehnder interferometer), by Anno- vazzi–Lodi [1] (laser diode) and by Luo [18] (erbium-doped fiber laser). The CSK method operates with digital information. The method again consists of modulating one of the oscillator parameters, thereby inducing a change in the chaotic dynamics of the oscillator, but the modulation is now binary. An eaves- dropper detects a pseudo-random or chaotic signal, whatever the value of the parameter, whereas a suitably synchronized chaos decoder can differentiate between a chaotic signal encoding a “1” bit and a chaotic signal encoding a “0” bit. Most Manuscript received December 18, 2000; revised March 6, 2001. This work was supported by European Contract FET/OCCULT. The authors are with GTL-CNRS Telecom, UMR CNRS 6603, Georgia Tech Lorraine, 57070 Metz, France, and with the Laboratoire d’Optique P.M. Duffieux, UMR CNRS 6603, Université de Franche-Comté, 25030 Besançon
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This note was uploaded on 10/18/2010 for the course MATH CS 301 taught by Professor Aliulger during the Fall '10 term at Koç University.

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chaos shift keying encryption system using chaos - IEEE...

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