RESULT ORIENTED APPROACH: RESERVING ROOM BEFORE ENCRYPTION IN REVERSIBLE DATA HIDING IN ENCRYPTED IMAGES
Abstract
Recently, reversible data hiding (RDH) in encrypted images is the most important property that the original cover can be lossless recovered after embedded data is extracted while protecting the image content’s confidentiality. Due to use of embedding data by reversibly vacating room from the encrypted images, this method may be subject to some errors on data extraction and image restoration. In this paper, we propose method by reserving room before encryption with a traditional reversible data hiding algorithm, and thus it is easy for the data hider to reversibly embed data in the encrypted image. This method can achieve real reversibility,data extraction and image recovery are free of any error. according to this method, it can embed more times as large payloads for the same image quality as the previous methods, such as for PSNR dB.
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Introduction
Reversible data hiding in images is a method, by which the original cover can be losslessly recovered after the embedded message is extracted. This method is widely used in medical, military imagery and law forensics, where no distortion of the original cover is allowed [1] [7]. In recent studies, many new RDH techniques have emerged. General framework for Reversible data hiding (RDH) can first extract compressible features of original image cover and then compressing them losslessly, spare space can be saved for embedding auxiliary data. Another method is difference expansion (DE)[2], which expanded the difference of each pixel group e.g., multiplied by 2, and thus the least significant bits (LSBs) of the difference are all-zero and can be used for embedding messages. Another strategy for RDH is histogram shift (HS), in which space is saved for data embedding by shifting the bins of histogram of gray values [6][8]. The state-of-art methods usually combined difference expansion DE or histogram shift HS to residuals of the image, e.g., the predicted errors, to achieve better performance [8].
Conclusion
Reversible data hiding in encrypted images is a new method which is popular due to the privacy-preserving requirements from cloud data management. Earlier methods implement RDH in encrypted images by vacating room after encryption, as opposed to which we proposed by reserving room before encryption. In this new technique data hider can benefit from the extra space emptied out in previous stage to make data hiding process effortless. The proposed method can achieve excellent performance without loss of perfect secrecy. and also real reversibility, separate data extraction and greatly improvement on the quality of marked decrypted images.