Color image encryption algorithm based on hybrid chaos and layered strategies

Abstract

As the need for information security grows, chaotic system-based digital image encryption algorithms have gained considerable interest in recent years. However, many existing algorithms rely solely on a single chaotic mapping for pixel or bit-plane encryption. While these methods provide a certain level of security, there is still room for improvement, particularly in enhancing encryption depth. This paper proposes a color image encryption algorithm based on hybrid chaos and layered strategies to address this issue. First, We confirm the strong chaotic behavior of the newly introduced Chebyshev–Tent (CT) mapping through a detailed analysis of its chaotic properties, including the Lyapunov exponent, bifurcation diagram, NIST SP 800-22 test, sample entropy analysis, 0–1 test analysis, and sensitivity to initial conditions. The chaotic sequences generated by CT and Sine-Tent-Cosine (STC) mapping are then jointly incorporated into the scrambling and diffusion processes. Furthermore, to enhance the randomness of the scrambling process, we present a chaotic Fisher–Yates scrambling algorithm based on chaotic sequences to scramble different layers of the image. This layered encryption approach, which combines the advantages of multiple chaotic mappings, not only improves encryption depth but also increases complexity across different image dimensions. The experimental results and security assessments demonstrate the robustness and reliability of the proposed algorithm.