A separable lossless data embedding scheme in encrypted images considering hierarchical privilege

This paper proposes a new scheme of separable lossless data embedding for encrypted images in which hidden data can be extracted from an image with embedded data even the image is encrypted. The proposed scheme firstly encrypts an image and simultaneously prepares room for lossless data embedding. Data are, then, concealed in the encrypted image by a lossless data embedding method based on histogram shifting, and the encrypted image carrying hidden data is sent to a receiver. According to key sets which the receiver has, he/she is allowed to take seven different actions based on hierarchy, whereas the conventional separable scheme offers only three actions. This feature of the proposed scheme extends applicable scenarios. Moreover, the proposed scheme always restore the original image, whereas the conventional scheme sometimes fails to do. Experimental results show the effectiveness of the proposed scheme.