基于改进混沌系统和扩散-置乱-扩散结构的图像加密算法OA

Aiming at the problems of dynamic degradation,weak resistance to attacks,and efficiency-security imbalance in traditional chaotic image encryption algorithms,this paper proposes a dynamically coupled image encryption algorithm based on an improved chaotic system.First,by introducing a sine-cosine nonlinear perturbation term to reconstruct the phase space of the Logistic map,a sine-logistic coupled system(SLCS)chaotic system is built.The improved system achieves enhanced state value cov-erage and expands the key space to 4.29×1069,which is 1062 times larger than that of the traditional Logis-tic map,effectively overcoming the periodic window phenomenon in low-dimensional chaos.Second,a three-stage diffusion-scramble-diffusion(DSD)framework is designed,incorporating dynamic row-scan permutation and block-wise cross-diffusion strategies.The bidirectional closed-loop diffusion mechanism ensures that a single-pixel modification triggers a global avalanche effect,achieving NPCR and UACI val-ues of 99.612%and 33.445%,respectively,which closely approach the theoretical ideals.Experimental results demonstrate that the proposed algorithm achieves RGB channel information entropy values exceed-ing 7.999 for standard 512×512 test images while effectively eliminating adjacent pixel correlations in plaintext.This research provides a high-security and computationally efficient solution for real-time en-cryption scenarios such as medical imaging and military communication.