After encrypting all the data of an uncompressed image by flow ciphering, the additional data can be embedded in the image by modifying a small proportion of encrypted data. With an encrypted image containing additional data, it can first be decrypted using the encryption key and the decrypted version is similar to the original image. According to the key of data concealment, with the help of spatial correlation in natural image, the embedded data can be extracted successfully and the original image can be perfectly recovered.
Reversible hiding of data in encrypted images is a technique that incorporates additional data into an encrypted image without having access to the content of the original image, can extract the embedded data and recover the encrypted image to the original. In this article, two methods of hiding reversible data in encrypted images are introduced, namely a binding method and a separable method, adopting a prediction error. In the joint method, data extraction and image reconstruction are performed at the same time. Reversibility, the number of incorrect extracted bits is significantly improved while maintaining a good visual quality of the recovered image, especially when the embedding rate is high. In the detachable method, data extraction and image recovery are separated. The detachable method also provides better reversibility and good visual quality of the recovered image for high payload incorporation.