Secure Reversible Data Hiding in Images with Scalable Capacity

In available reversible data hiding methods, the capacity of hidden information is basically fixed when the host media is fixed, that is, the capacity lacks scalability. In order to enhance the security of hidden data, encryption technology is often combined with reversible data-hiding methods. However, commercial encryption algorithms due to their complexity will increase the burden, making it difficult to achieve real-time data processing on simple devices. This paper aims to propose a secure fusion of multiple sensitive data, such as various temporal sensing data, by the combination of reversible image data hiding and lightweight encryption technology, achieving a scalable capacity of hidden data. Specifically, the image is divided into non-overlapping sub-blocks, and the number of blocks is calculated based on the amount of data to be hidden. Then, reversible data hiding is performed independently on each block based on block histogram shifting. Using the international standard test images as the host carriers, the feasibility of the scheme is verified through experiments, and the relationship between the number of image blocks and the amount of data that can be hidden, as well as the number of image blocks and the fidelity of the steganographic image is revealed. Although this paper introduces grayscale images as carriers, the proposed algorithms and conclusions are fully applicable to color images.