Reversible data hiding in encrypted images based on horizontal and vertical pixel shifting and dynamic block partitioning

To address the limited embedding capacity of existing Reversible Data Hiding in Encrypted Images (RDHEI) schemes, this paper proposes a novel method that integrates bidirectional pixel shifting with a dynamic block partitioning strategy. By modeling encrypted image pixels as horizontal and vertical circular queues, the proposed scheme enables dual-layer data embedding through pixel permutation without modifying pixel values, thereby strictly preserving the statistical characteristics of encrypted images. Furthermore, a dynamic block partitioning mechanism is designed to adaptively select between 2 × 2 and 4 × 4 block structures based on block recoverability, achieving an effective balance between embedding capacity and extraction reliability. Extensive experiments conducted on the BOWS-2, BOSSBase, and UCID datasets demonstrate that the proposed method achieves average embedding rates of 0.7156, 0.7241, and 0.6290 bpp, respectively, significantly outperforming state-of-the-art pixel rearrangement–based RDHEI methods. The experimental results also confirm perfect reversibility and strong resistance to statistical analysis.