A Novel Reversible Data Hiding in Encrypted Images by Controlled Swapping of Adjacent Pixels

Abstract

Reversible data hiding (RDH) got much attention in the past few years due to its applications in various areas. In this research, we have considered the challenging task of performing RDH in encrypted images. The security of the image encryption process is mainly evaluated using two types of analysis: one is the entropy measure and the other is histogram analysis. The RDH schemes in encrypted images always result in some alterations in the entropy measure and some changes in the histogram of the encrypted images. In this paper, we propose a novel RDH scheme that will be capable to generate an encrypted image with hidden data without any change in the entropy and in the histogram. The new algorithm is a block-wise RDH process in which the data hider can hide one single bit of additional data in an encrypted image block having size $B\times B$ pixels. The pixels of a selected block will be divided into two groups: white pixels and black pixels. The classification of pixels is done based on the checkerboard pattern. The block will remain unchanged to hide a bit value 0, and all the adjacent white pixels and black pixels will be swapped to hide a bit value 1. To extract the hidden bits at the time of image restoration, the closeness between the pixel intensity value is analyzed. The experimental results show that the new RDH schemes provide a good embedding rate without affecting the bit error rate.