Multiple medical image encryption algorithm based on scrambling of region of interest and diffusion of odd-even interleaved points

Abstract

Due to the security requirement brought by the rapid development of electronic medical, this paper proposes an encryption algorithm for multiple medical images. The algorithm can not only encrypt grayscale medical images of any number and any size at the same time, but also has good encryption effect when applied to color images. Considering the characteristics of medical images, we design an encryption algorithm based on the region of interest (ROI). Firstly, extract the region of interest of the plaintext images and obtain the coordinates, calculate the hash value of the large image composed of all plaintext images. Set the coordinates and hash value as the secret key. This operation makes the whole encryption algorithm closely related to the plaintext images, which greatly enhances the ability to resist chosen plaintext attacks and improves security of the algorithm. In the process of encryption, chaotic sequences generated by Logistic-Tent chaotic system (LTS) are used to perform two scrambling and one diffusion, that is, pixel swapping based on the region of interest, Fisher-Yates scrambling and our newly proposed diffusion algorithm based on odd–even interleaved points. After testing and performance analysis, the algorithm can achieve good encryption effect, can resist various attacks, and has a higher security level and faster encryption speed.