A secure image encryption scheme based on a complex 3D chaotic system and an enhanced Josephus ring for IoT environments

Abstract With the rapid proliferation of Internet of Things (IoT) devices, a vast volume of image data is continuously generated, raising significant concerns about data security and privacy. This paper proposes a novel image encryption scheme suitable for IoT environments, leveraging a complex three-dimensional (3D) chaotic system and an enhanced Josephus ring scrambling mechanism. The proposed chaotic system is developed by modifying the Liu chaotic model, expanding its parameter space and improving sequence randomness and unpredictability. Furthermore, the Josephus ring scrambling technique is refined by integrating the Fibonacci sequence and a main diagonal matrix model, replacing conventional element deletion with position swapping to increase the scrambling efficiency. To reinforce diffusion, a hybrid approach combining DNA rotation coding and dynamic DNA coding is applied, significantly increasing the complexity of pixel transformation. In addition, a dynamic ciphertext feedback mechanism employing four distinct chaotic sequences conceals key-related information and increases the cryptographic strength. Extensive experimental evaluations, including key space analysis, statistical assessments, sensitivity tests, and resistance to differential attacks, demonstrate the robustness, efficiency, and suitability of the proposed method for secure image transmission in IoT systems.