Reversible data hiding in encrypted image using bit-plane based label-map encoding with optimal block size

Abstract

In today’s digital landscape, maintaining the confidentiality and privacy of sensitive information has become an essential requirement. For this, Reversible data hiding in encrypted images (RDHEI) has garnered considerable attention as it enables embedding of large amounts of secret data in encrypted images without requiring knowledge of the original image contents. To further increase the embedding capacity (EC) while maintaining security, this paper presents a new bit-plane-based RDHEI using label-map encoding with optimal block size. The proposed method employs a hybrid predictor to generate a low-magnitude difference image, which is transformed into highly compressible bit-plane-wise label-maps. A novel block-based label-map encoding is also introduced, which optimally represents these label-maps as bit-streams to significantly reduce their size. These bit-streams are embedded in the original encrypted image to guide the data hider, ensuring complete reversibility and lossless extraction at the receiving end. Extensive experimentation shows that the proposed method achieves an average embedding rate of 3.8770 bpp for BOSSBase and 3.7944 bpp for BOWS-2, outperforming state-of-the-art RDHEI methods. Further, the method ensures lossless reconstruction of the original image and error-free extraction of hidden data while demonstrating strong resilience against malicious attacks.