Fractional discrete cosine transform based image cryptography

Abstract

In this digital era, most of us spend a fairly good amount of time on social media platforms newlinesharing stories, uploading images, and therefore share important information in the chan- newlinenel. The enormous amount of multimedia content is subjected to significant risk due to the newlinepresence of eavesdroppers ready to get easy access to multimedia data in an insecure and newlineunreliable channel. This includes sensitive information like medical data/records of patients, newlinewhich have been transmitted regularly in the post-covid era. Cryptography consists of en- newlinecryption and decryption of images in a secured manner. It is a tremendous tool and the newlinebasis of various security mechanisms. In encryption, the images are secured by converting newlinethem into cipher images with the help of some key and again retrieving the original image newlinewith the help of the same key. There has been growing interest amongst researchers since newlinethe last few decades to develop cryptosystems to protect the data from any sort of vulner- newlineabilities. Several scientific techniques have been experimented with and implemented to newlineensure the secrecy and privacy of users. The vulnerability of cryptosystems is high if the newlinedata is encrypted in spatial domain. Therefore, several approaches have been constructed newlineto encrypt the multimedia data in the transform domain. Cryptography in the fractional do- newlinemain emerged as a breakthrough in this field. The fractionalization of the transforms added newlinean extra degree of freedom or layered security, with the fractional multi-orders adding an newlineadditional security feature to the algorithms and strengthening the robustness and the secu- newlinerity level of cryptographic systems. The study of fractional Fourier transform (FrFT) in the newlinefield of quantum mechanics applications first brought the concept. With the growing de- newlinemand of multimedia data, especially color images, which are most often in use, it became newlineinevitable to design novel schemes of cryptography that are more robust. However, the out- newlineput of FrFT contains both real and complex terms leading