An improved Reversible Data Hiding for Encrypted Images over Cloud

Abstract

Recently, Reversible Data Hiding produced notable contributions to the data security and privacy protection of encrypted images in cloud environment. This inspired the research topic namely Reversible Data Hiding in Encrypted Images (RDHEI) which allows embedding of auxiliary data/meta data into an already encrypted image so that the original content of the image is privileged. Earlier works on RDHEI show less efficiency in embedding capacity because encrypted images show inadequacy in possessing redundant space. The motivation of the proposed work is to fully exploit the available space in encrypted images for maximal data embedding. In this paper, an improved fully separable RDHEI is proposed using Effective Block Scrambling (EBS) and Overlapping Pixel Value Ordering (OPVO) to improve embedding capacity of encrypted images. The proposed scrambling technique is based on chaotic map and block wise XOR encryption. After the encryption, the data hider performs embedding by dividing the encrypted image into nonuniform blocks followed by three-mode application of Overlapping Pixel Value Ordering. At receiver end, original image can be extracted with three possible cases upon the availability of secret keys. Experimental results emphasize the efficacy of the proposed method which prevails over the state-of-the-art methods.