Reversible data hiding in Redundancy-Free cipher images through pixel rotation and multi-MSB replacement

Reversible data hiding in encrypted images (RDH-EI) has gained significant attention as a solution to content security challenges in cloud-based image storage. A key challenge in this field is to achieve large-capacity data hiding directly within secure ciphertexts without relying on any redundancy. This paper proposes a scheme for achieving high-capacity reversible data hiding in ciphertext images without redundancy. By combining stream cipher XOR and pixel permutation encryption, the generated ciphertext eliminates redundant information, making it resistant to existing cryptographic attacks. In the data embedding phase, we first rotate the positions of pixels within the image blocks and adjust the arrangement of pixel bit-planes to effectively exploit spatial position features for reversible data hiding. Subsequently, we exploit the embedding potential of the central pixel by applying MSB replacement, further increasing the embedding capacity. We introduce a novel method for calculating image block complexity to enhance image recovery quality, considering pixel correlations within and between adjacent blocks. Experimental results show that the proposed RDH-EI scheme achieves a maximum embedding capacity close to 1 bpp, significantly higher than both classical and state-of-the-art algorithms. Moreover, the algorithm is resilient to potential attacks, such as forgery attacks.