Secure Sudoku Mapping for Dual-Image Reversible Data Hiding
TL;DR
The experiments show that the proposed architecture provides predictable payload, low carrier-domain distortion, authenticated framing, and exact recovery while retaining standard image encryption.
Abstract
Reversible data hiding in encrypted images (RDHEI) often creates embedding room by preserving or preprocessing image redundancy, thereby coupling the hiding layer to a specialized encryption model. This paper presents a dual-image method that works directly on AES-CTR ciphertext. Its design rests on four elements: a keyed Sudoku coordinate code for carrying two base-8 digits per accepted pair; exact reconstruction of each ciphertext pair from inter-block displacement; AES-GCM framing for payload confidentiality and integrity; and an adaptive movement threshold that selects the lowest-distortion mappings able to accommodate the complete frame. The data hider requires neither plaintext nor the image-encryption key, and no location map is transmitted. On sixteen 512×512 grayscale images, the method achieves a mean maximum net rate of 1.4187 bits per transmitted pixel. At ERt=1.0, the two marked outputs reach mean PSNR values of 47.65 dB, and all 160 image-rate trials yield zero payload error and pixel-exact recovery. An independent implementation of the embedding and recovery layer of Venkatesh et al. is also examined; published and reproduced results are reported separately where the original specification leaves ambiguity. The experiments show that the proposed architecture provides predictable payload, low carrier-domain distortion, authenticated framing, and exact recovery while retaining standard image encryption.