Reversible data hiding method in encrypted images using secret sharing and Huffman coding

Early works on reversible data hiding in encrypted images (RDHEI) usually generate only one encrypted image from the original image, if the encrypted image is lost or maliciously damaged by an attacker, all information about the original image will be lost. Thus, storing images in distributed servers is an effective solution. Therefore, this paper proposes an RDHEI method using (k, n)-threshold secret sharing. It is not a traditional secret sharing technique, but takes its principles and ideas. In this algorithm, we combine the image encryption and sharing process to generate n shares and send them to the cloud for storage. It maintains the advantage of (k, n)-threshold secret sharing technique that only at least k shares can successfully recover the original image while less than k shares cannot. In addition, the size of each share is smaller than the original image, so that it can save storage spaces. By Huffman coding the pixel difference in the encrypted image block, secret data are embedded into these shares. It is a full reversible method that data extraction and image recovery are performed separately and losslessly. Simulation results, comparisons and security analysis are demonstrated to show superior performances of the proposed algorithm.