A novel 4D fractional-order chaotic system provides robust encryption for ECG signals, demonstrating high security against statistical and differential attacks.
This paper introduces a novel four-dimensional (4D) fractional-order (FO) chaotic system inspired by meminductor dynamics. The system's fundamental dynamics are characterized through phase portraits, bifurcation diagrams, Lyapunov exponents, and Kaplan-Yorke dimension, confirming behavior over a wide parameter range. A significant feature of the proposed system is the integration of a unified piecewise-linear (PWL) function, enabling the controllable generation of 1D, 2D, and 3D multi-scroll attractors. To demonstrate a potential application, the proposed system is utilized in a chaos-based encryption scheme for Electrocardiogram (ECG) signals, aiming to enhance patient data privacy during transmission or storage. The proposed cryptosystem features a plaintext-dependent key generation mechanism and a robust permutation-diffusion architecture. Security analyses performed on the encrypted ECG signal, including histogram uniformity, correlation, information entropy, Number of Pixels Changing Rate (NPCR), and Unified Average Changed Intensity (UACI), yield results close to ideal theoretical values (e.g., information entropy ≈ 7.9984, correlation coefficient ≈ 0.0030, NPCR ≈ 99.63 %, and UACI ≈ 33.54 %). This demonstrates the encryption scheme's effectiveness against common statistical and differential attacks. In addition, an STM32H7-based digital realization reproduces the main chaotic attractors via dual-DAC outputs, confirming the feasibility of low-cost embedded implementation.
Sağbaş et al. (Wed,) studied this question.