An Effective Image Encryption Method Based on Space Filling Curve and Plaintext-Related Josephus Traversal

To improve the effectiveness and security of image encryption, this article proposes an image encryption scheme based on a Y-index Space Filling Curve (SFC) and variable step Josephus traversal. The scheme adopts a confusion-diffusion structure. First, a novel Y-index SFC is designed. SFC is a method of continuously traversing each pixel of an image to encrypt the image, and images are confused by the Y-index SFC. Second, the random sequences generated by the chaotic map are taken as the starting point and step length of the Josephus traversal, and the pixels of the image are scrambled at a bit-level to change the values of the pixels. By changing the step length, the diversity of the Josephus traversal is increased. Finally, ciphertext feedback and chaotic sequence operations are used to further enhance the confusion and diffusion characteristics of the algorithm. By analyzing the experimental results and comparing them with the results of other image encryption algorithms, we show that this algorithm performs better and achieves higher security than other algorithms.