TY  - EJOU
AU  - Mohamed, Mohamad Afendee 
AU  - Bonny, Talal 
AU  - Sambas, Aceng 
AU  - Vaidyanathan, Sundarapandian 
AU  - Nassan, Wafaa Al 
AU  - Zhang, Sen 
AU  - Obaideen, Khaled 
AU  - Mamat, Mustafa 
AU  - Nawawi, Mohd Kamal Mohd 

TI  - A Speech Cryptosystem Using the New Chaotic System with a Capsule-Shaped Equilibrium Curve
T2  - Computers, Materials \& Continua

PY  - 2023
VL  - 75
IS  - 3
SN  - 1546-2226

AB  - In recent years, there are numerous studies on chaotic systems with special equilibrium curves having various shapes such as circle, butterfly, heart and apple. This paper describes a new 3-D chaotic dynamical system with a capsule-shaped equilibrium curve. The proposed chaotic system has two quadratic, two cubic and two quartic nonlinear terms. It is noted that the proposed chaotic system has a hidden attractor since it has an infinite number of equilibrium points. It is also established that the proposed chaotic system exhibits multi-stability with two coexisting chaotic attractors for the same parameter values but differential initial states. A detailed bifurcation analysis with respect to variations in the system parameters is portrayed for the new chaotic system with capsule equilibrium curve. We have shown MATLAB plots to illustrate the capsule equilibrium curve, phase orbits of the new chaotic system, bifurcation diagrams and multi-stability. As an engineering application, we have proposed a speech cryptosystem with a numerical algorithm, which is based on our novel 3-D chaotic system with a capsule-shaped equilibrium curve. The proposed speech cryptosystem follows its security evolution and implementation on Field Programmable Gate Array (FPGA) platform. Experimental results show that the proposed encryption system utilizes 33% of the FPGA, while the maximum clock frequency is 178.28 MHz.
KW  - Chaos; chaotic systems; hidden attractors; multi-stability; bifurcation; speech cryptosystem; FPGA design

DO  - 10.32604/cmc.2023.035668