Separable reversible data hiding in an encrypted image using the adjacency pixel difference histogram

Abstract

Information security is a practice of encrypting data in movement and on hold, improving discretion and integrity. One can protect, encrypt and decrypt critical data in several ways. One of them is reversible data hiding in an encrypted image. The technique enables the user to encrypt images that need authentication and restore them to their original form of images. This technique returns a lossless image as an output making it the most suiTable for medical images and the military. Histogram shifting of pixel difference is an effectual reversible data hiding method in information security. Each image's pixel is encrypted when a user wants to safely store a digital image in an open environment like a cloud. The authentication or any other relevant information related to that image is embedded in the pixel difference histogram. The proposed approach's advantage is that the grayscale image transfer is carried out exceedingly safely, with near-zero correlation and Entropy closer to 8. The Peak Signal Noise Ratio (PSNR) for a directly decrypted image with an embedding capacity of 0.0807 bpp is 50.84 dB. Moreover, the secret and cover images are retrieved without error.