Reversible Data Hiding in Pairwisely Encrypted Images

This work proposes a novel separable method for encrypted images. The input image is encrypted first via a pairwise encryption scheme. Then the data bits can be embedded into the pairwisely encrypted image by the well-known difference-expansion technique. When the receiver gets the marked encrypted, he can extract the secret data bits by the data-hiding key and obtain an image which is similar to the original input image by the encryption key. Furthermore, he can recover the original image and extract the secret data bits once he owns both encryption and data-hiding keys. To compare the existing separable methods which do not pre-reserve space for embedding secret data, experimental result shows that the proposed scheme obtains much better embedding capacity.