Reversible Data Hiding in Encrypted Images Based on Progressive Recovery

Abstract— A method of reversible data hiding in encrypted images (RDH-EI) based on progressive recovery. Three parties are involved in the framework, including the content owner, the data-hider, and the recipient. The content owner encrypts the original image using a stream cipher algorithm and uploads ciphertext to the server. The data-hider on the server divides the encrypted image into three channels and respectively embeds different amount of additional bits into each one to generate a marked encrypted image. On the recipient side, additional message can be extracted from the marked encrypted image, and the original image can be recovered without any errors. While most of the traditional methods use one criterion to recover the whole image, we propose to do the recovery by a progressive mechanism. Rate-distortion of the proposed method outperforms state-of-the-art RDH-EI methods. It is feasible in the applications like cloud storage and medical systems. In cloud storage, a content owner can encrypt an image to preserve his/her privacy, and upload the encrypted data onto cloud. On the cloud side, when managing huge amount of encrypted images, an administrator can embed additional messages (e.g., labels, time stamps, category information, etc.) into the ciphertext. This embedding not only saves the storage overhead, but also provides a convenient way of searching encrypted images. On the recipient side, when a user downloads the encrypted data containing additional messages from the server, he/she can losslessly recover the original images after decryption. < final year projects >