Reversible Data Hiding in Encrypted Images Based on Reversible Integer Transformation and Quadtree-Based Partition

This paper presents an improved secure reversible data hiding scheme in encrypted images based on integer transformation, which does not need using a data hider key to protect the embedded secret data. We first segment the original image into blocks of various sizes based on the quadtree-based image partition. For each block, we reserve m least significant bits (LSBs) of each pixel as embedding room based on the reversible integer transformation. In order to improve the security of the image encryption, we pad the mLSBs of each pixel using the corresponding (8-m) most significant bits (MSBs) information after the transformation, which protects the security of the encryption key. Then, we encrypt the transformed image with a standard stream cipher. After the image encryption, the data hider embeds the secret data in the mLSBs of the encrypted images through an exclusive or operation. On the receiving side, the receiver can extract the secret data after the image decryption and recover the original image without loss of quality. The security analysis shows that the proposed scheme improves the security weakness of the scheme directly using adaptive integer transformation. The experimental results show that the proposed method achieves a higher embedding ratio compared with several relevant methods.