Separable reversible data hiding in encrypted images based on flexible preservation of the differences
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Separable reversible data hiding in encrypted images based on flexible preservation of the differences Li Liu 1,2 & Lifang Wang 2 & Chin-Chen Chang 3,4 Received: 21 May 2020 / Revised: 30 July 2020 / Accepted: 2 September 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
To better protect the security of users’ private data in the cloud environment, the technology for separable reversible data hiding in encrypted images has been attracting increasing attention from researchers. In this paper, we propose a separable reversible data hiding scheme in encrypted images based on the flexible preservation of differences. This scheme has three parts: 1) For the content owner, the original image is divided into non-overlapping blocks, for which block-mean is computed. Then the differences between the values of every pixel and the block-mean are obtained and an initial label map is generated. Because most of the differences tend to concentrate around 0, we use two bits to dynamically record the range of the differences to vacate space for hiding. Further, introducing the block-mean differences also serves to vacate more space, for which the label map is amended accordingly. Finally, the image with free space is encrypted into the encrypted image using an encryption key. 2) For the data hider, the secret bits are embedded into the encrypted image by directly replacing the spare bits without obtaining any information of the original image. 3) For the receiver, he/she can achieve the desired information according to the key in his/her possession. Experimental results show that our proposed scheme is able to achieve an average embedding capacity as large as 1.785 bpp and 1.709 bpp when block size is set to 2 × 2 and 2 × 4, respectively. Comparison with those of previous schemes, the proposed scheme has excellent embedding capacity, especially for smoother images. Keywords Reversible data hiding . Separable . Encryption . Difference
1 Introduction The popularization of cloud computing has spurred the development of computer network technology, which has resulted in the network environment becoming increasingly complex. The need for network security and privacy protection on the cloud platform brings even more
* Chin-Chen Chang [email protected] Extended author information available on the last page of the article
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challenges [2, 4]. Combining traditional encryption with data hiding technologies can provide dual protection for the security of user data, and has also spawned a new technology, i.e. reversible data hiding in encrypted images (RDH-EI) [1, 3, 6, 8, 16, 28]. To ensure the security of images during storage and transmission processes, images to be transmitted are first encrypted into meaningless images, and then additional information, such as IDs or parameters for management, are embedded into the meaningless encrypted images. At the receiving end, the receiver can recover the original images without experiencing any loss. However, it is difficult an
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