Efficient reversible data hiding in encrypted images using Block Complexity and most significant bit inversion strategy

Reversible data hiding in the encrypted images (RDHEI) has attracted more attention because RDHEI can be used for both information protection and image encryption. Many researches based on RDHEI have been proposed by using the Most Significant Bit (MSB) inversion to embed confidential information, but they might subject to errors when extracting the hidden information. This paper improves the approach based on MSB inversion and proposes a new RDHEI technique. Our approach hides the block’s position of the block in the image, which would cause misinterpretation in the original image, and then encrypts the image. The MSB inversion strategy is applied to embed the secret messages in the encrypted image. Since the location information of the error block is pre-hidden in the image, this information ensures that the secret message is correctly extracted and the image is fully recovered. We also created a multi-regular block complexity formula to determine the secret bits hidden in a block and recover the original block. In addition, we extended the design of four methods to cover various segmentation strategies and complexity calculation methods. According to the experimental results, our method can successfully extract the secret message and recover the original image intact after the encrypted image is embedded with the secret message. Generally, in using different image size, we averagely achieve the PSNR and embedding capacity of 39 experimental images at 40.633 dB and 46,298.46 bits, respectively.