| Chaotic image encryption technology has become a research hotspot due to its high randomness,sensitivity,and nonlinearity.However,traditional chaotic maps suffer from issues such as insufficient randomness,local chaotic behavior,and chaotic degradation.As the quality of the chaotic system directly affects the encryption results,it is crucial to construct a superior performing chaotic system before encryption.This study delves into the coupling and cascading methods for constructing chaotic systems and applies them to grayscale and color image encryption,as described below:(1)Chapter three proposes a novel coupled and cascaded method for constructing a2 D chaotic system by combining feedback coupling,hybrid coupling,and serial cascading principles.Using the Sine map and 1D Henon map as seeds and further adjusting them through the mathematical remainder method,the 2D ESHHM is constructed.Compared to existing 2D chaotic systems,this system exhibits superior pseudorandomness.Based on the 2D ESHHM,a grayscale image encryption algorithm is designed.By generating an adaptive key related to the plaintext and applying the encryption steps of forward diffusion-scrambling-reverse diffusion,the original image’s spatial correlation is disrupted by double scrambling,and the ciphertext feedback mechanism in the diffusion stage achieves time correlation between ciphertexts.Comprehensive metric evaluations and experimental analyses compared with recent literature in the past two years demonstrate the proposed algorithm’s superior security in grayscale image encryption.(2)Chapter four proposes a method for constructing chaotic systems using dynamic nonlinear coupled map lattice(DNCML)based on the novel coupled and cascaded method from chapter three.By increasing the dynamics through parallel cascading Chebyshev maps on top of the coupled map lattice(CML)basic structure and disturbing adjacent coupled items with a unidirectional feedback coupling Arnold map,the DNCML is obtained.The Schwefel and Griewank maps are selected as seeds for the DNCML system,resulting in the SG-DNCML chaotic system through the new coupling-cascading method.Comprehensive evaluations of performance metrics and comparisons with representative chaotic systems proposed in the past two years verify the SG-DNCML system’s excellent performance.Based on the SG-DNCML chaotic system,a color image encryption algorithm is designed.Resistance to chosen plaintext attacks is achieved by generating encryption keys through SHA-256 function and Merkle trees.The core encryption steps of scrambling-diffusion-scrambling are applied with different strategies for the R,G,and B channels before merging the three channels into ciphertext.Comprehensive metric evaluations and comparative experimental analyses prove that the algorithm has broad application prospects and sufficient security in the field of color image confidential communication,effectively resisting various attacks.Figure [35] Table [9] Reference [81]... |
