Reversible Data Hiding With Flexible Extraction for Thumbnail-Preserving Encryption

Storing images in the cloud not only facilitates consumers management of their images, but also alleviates the storage burden on local consumer electronic devices, a convenience that often comes at the expense of privacy. Traditional image encryption protects image privacy from disclosure, but sacrifices the visual usability of the images. Thumbnail-preserving encryption (TPE) is a recently proposed encryption scheme that harmonizes the privacy and usability of images. However, most existing TPE schemes ignored the non-visual usability of the images, i.e., the ability to embed additional information into the TPE images, which resulted in insufficient usability of the TPE images. To this end, we propose a TPE scheme for flexible extraction of reversible data hiding (RDH), which utilizes the histogram shifting technique to achieve embedding and lossless extraction of information at different stages before and after permutation encryption. Importantly, the encrypted image can be recovered losslessly. Meanwhile, we integrate a chaotic system into the encryption and decryption processes, thereby significantly reducing computational time and enhancing overall efficiency. Experiments show that our proposed scheme not only embeds additional information in TPE images, but also recovers the original images losslessly.