A Lightweight FPGA Implementation of Chaos-Based Image Encryption Using FiveFractional Order Chaotic Cryptosystems

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Abstract

Abstract This article presents an encryption system based on fractional-order chaoticoscillators and its implementation on an FPGA device. Unlike conventionalapproaches, the proposed system analyzes and exploits the dynamics offractional-order chaotic oscillators to strengthen security in encryption schemes.First, we generate the discrete chaotic signals of each oscillator using theAdams–Bashforth–Moulton (ABM) and the explicit fractional-order Runge–Kutta (EFORK) numerical methods. In addition, we incorporate a Hamiltonianmaster–slave synchronization scheme to deterministically produce the sameencryption key at both the transmitter and the receiver. Next, we apply theleast significant bits (LSB) technique to perform chaotic encryption. Finally, wereport synchronization and encryption results for five chaotic oscillators: Lorenz,Rabinovich–Fabrikant, Li, Chen, and Yu–Wang, validating the performance ofthe proposed system. In the encryption tests, we obtained minimum correlationcoefficients of 0.0000412 for an RGB color image and 0.000910 for a grayscaleimage; in terms of entropy, we achieved maximum values of 7.999315 for RGB1and 7.9994184 for grayscale. Lastly, our hardware implementation analysis showsthat the encryption system requiring the fewest logic resources is the Li oscilla-tor solved using EFORK, which uses a total of 38673 LUTs, corresponding to28.7% of the total resources available on the Xilinx FPGA Artix-7 board (chipXC7A200TFBG676-2).