Abstract
This paper deals with the design of a fractional-order chaotic secure communication scheme. On the emitter side, a fractional-order Chua's system is used as the drive system to generate the encrypted message signal. The input secret message is modulated in the chaotic dynamics by inclusion rather than being directly added to the chaotic signal on the transmission line. A single channel is used for transmission of the encrypted signal. At the receiver side, a step-by-step sliding mode fractional-order chaotic observer subject to unknown input is proposed as the response system to obtain robust synchronization between the emitter and the receiver. After chaos synchronization is achieved at the receiver side, an estimation of the state variables is obtained and the plaintext is recovered. Finite-time convergence of both state and unknown input estimation errors is established. The efficiency of this proposed secure communication scheme is illustrated by numerical simulations.