A separable reversible data hiding in encrypted image with improved performance

This work proposes a novel scheme to reversibly hide data into encrypted grayscale image in a separable manner. During the first phase, the content owner encrypts the image by permuting the pixels using the encryption key. The data hider then hides some data into the encrypted image by histogram modification based data hiding, making use of data hiding key. At the receiver side, if the receiver has only encryption key, he can generate an image similar to the original one, but cannot read the hidden data. Peak Signal to Noise Ratio (PSNR) of this decrypted image is much higher than the existing methods. If the receiver has only data hiding key, he can extract the data, but cannot read the content of the image. If the receiver has both keys, he may first extract the data using data hiding key and then decrypt the image using encryption key. The method also has a higher data hiding capacity than the existing reversible data hiding techniques in encrypted image.