Abstract: Reversible data hiding (RDH) has captured most of the attention in the field of encrypted images, RDH has ability to maintain the strong property that the original cover can be easily be recovered after embedded data is extracted while protecting the image contentís confidentiality. Available methods embed data by reversibly vacating room from the encrypted images that leads to some errors on data retrieval and/or image recreation. In this paper, we propose a novel method by reserving image space before encryption with a traditional RDH algorithm, and thus it is easy for the data hider to reversibly embed data in the encrypted image. The proposed method can achieve real reversibility, that is, data retrieval and image recreation are free of any error. Experiments show that this novel method can embed more than 10 times as large payloads for the same image quality as the previous methods, such as for PSNR dB.

Keywords: Reversible data hiding, image encryption, privacy protection, histogram shift.