Plaintext-Related Image Encryption Algorithm Based on Block Structure and Five-Dimensional Chaotic Map

In this paper, a five-dimensional discrete hyperchaotic map is constructed by combining Logistic map and 3D discrete Lorenz map. Based on this chaotic system, a block-based image encryption scheme related to plaintext is designed. The encryption scheme includes scrambling operation and diffusion operation. In the scrambling operation, the scrambling sequence is related to the pixels of the plaintext image, while in the diffusion operation, two rounds of diffusion are carried out for intra-block diffusion, and the generation of random diffusion sequence is related to a pixel value in the block in each round of diffusion, which makes the algorithm resist chosen-plaintext attack. When the next block is diffused, the generation of the diffusion sequence is related to the first and last pixels of the previous block, which makes the block and block interact with each other and enhances the sensitivity of the algorithm to plaintext. Theoretical analysis and experimental results demonstrate the security and practicability of the cryptosystem.