Separable reversible data hiding in encrypted images with histogram permutation

This paper proposes a new method of separable reversible data hiding (RDH) for encrypted images in which hidden data can be extracted from an encrypted image conveying hidden data without image decryption. By histogram and spatial permutation, the proposed method firstly encrypts an image and simultaneously prepares room for RDH. Data are, then, hidden into the encrypted image by a RDH scheme based on histogram modification, and the encrypted image with hidden data is sent to a receiver. According to keys which the receiver has, he/she is allowed to take seven different actions, whereas the conventional method offers only three. This feature of the proposed method extends applicable scenarios. Moreover, the proposed method always recovers the original image, whereas the conventional method sometimes fails to do. Experimental results show the effectiveness of the proposed method.