<p>In the field of image encryption, some existing chaotic encryption schemes suffer from various security flaws, such as uneven distribution of phase trajectories of chaotic systems, narrow chaotic range, and easy cracking of encryption algorithms. To address these problems, in this paper, we improve the Chen chaotic system to construct a new hyperchaotic system and propose an image encryption scheme based on this system. First, a new state variable, a nonlinear term, and parameters are introduced to the Chen chaotic system to construct a hyperchaotic system, and its chaotic behavior is verified through dynamics analysis. Second, the SHA-384 hash function, plaintext message, and external keys are used to generate the chaotic initial key. The chaotic sequence generated by the system is used to produce an integer matrix, and the 8-bit binary matrix of the plaintext image undergoes parity rule transformation, followed by rule cyclic shifting and conversion to decimals. The image is subsequently randomly divided into two random numbers generated by the chaotic system. Each block is converted into a one-dimensional sequence, exchanged and spliced according to indices generated by the chaotic system, and then the index sequence generated in ascending order of chaotic sequences is used for index permutation, which is then restored into an image matrix. Finally, the image is converted into a one-dimensional sequence and diffused by crossing from the center first to the left and then to the right, resulting in the encrypted image. Simulation experiments and security analysis demonstrate the algorithm’s ability to efficiently encrypt grayscale images while effectively defending against various attacks.</p>