Reversible Data Hiding in Encrypted Image Based on Multi-MSB Embedding Strategy

Dewang Wang,Xianquan Zhang,Chunqiang Yu,Zhenjun Tang

doi:10.3390/app10062058

Abstract

In this paper, a reversible data hiding method in encrypted image (RDHEI) is proposed. Prior to image encryption, the embeddable pixels are selected from an original image according to prediction errors due to adjacent pixels with strong correlation. Then the embeddable pixels and the other pixels are both rearranged and encrypted to generate an encrypted image. Secret bits are directly embedded into the multiple MSBs (most significant bit) of the embeddable pixels in the encrypted image to generate a marked encrypted image during the encoding phase. In the decoding phase, secret bits can be extracted from the multiple MSBs of the embeddable pixels in the marked encrypted image. Moreover, the original embeddable pixels are restored losslessly by using correlation of the adjacent pixels. Thus, a reconstructed image with high visual quality can be obtained only when the encryption key is available. Since exploiting multiple MSBs of the embeddable pixels, the proposed method can obtain a very large embedding capacity. Experimental results show that the proposed method is able to achieve an average embedding rate as large as 1.7215 bpp (bits per pixel) for the BOW-2 database.

Highlights

Image encryption and data hiding are two main means for data security
Traditional data hiding technology is usually irreversible, and the embedding process will bring permanent distortion to the original carrier, which is not accepted in some cases such as military images, medical images, and judicial evidence collection where the original carrier needs to be restored without distortion
We can see that in some cases, the embedding rate of some images is very low or even 0 when the value of m is small. This is mainly because the number of embeddable pixels will be few for moderate smooth images when the value of m is small

Summary

Introduction

Image encryption and data hiding are two main means for data security. The former aims to transform the meaningful image into a noise-like one to prevent image content leakage [1,2,3,4], while the latter embeds secret data into a cover image imperceptibly. Tian [9] proposed an RDH method using difference expansion (DE). This method divides an image into a series of pixel pair and embeds a secret bit into a pair of pixels by expanding the difference of this pixel pair. Based on the DE method, some improved reversible data hiding algorithms were proposed in [10,11,12,13] Another classic reversible data-hiding algorithm is histogram shifting (HS) [14,15,16,17,18,19,20,21]. The peak bin is expanded for data embedding, and the other bins need to be shifted for reversibility Among these methods, HS-based methods can achieve better embedding performance

Methods

Results

Conclusion