Abstract

This work focuses on enhancing security for transmitted e-documents, such as e-stamp papers, within wireless environments through dynamic authentication using variable circular concealment of multiple invisible signature images. This method is driven by encrypted secret keys and session-based random numbers, alongside a region-specific bit casting strategy and dynamic bit sequencing for multiple signatures to bolster security and robustness. Multi-copy signature marking on non-overlapping document areas, coupled with varied bit encoding strategies for each modified pixel byte coefficient in cover image sub-blocks, further enhances protection and resilience against attacks. The reverse transformation of bit-coded pixel byte components in spatial domain ranges is preserved, allowing threshold-based bit creation to perform effectively even under attack scenarios. With secret information and random numbers transmitted to the receiver, the securely embedded signature bits can be reliably identified in their original sequence from the forward-transformed sub-block pixel elements. Experimental results validate that this approach significantly improves authentication and confidentiality, surpassing prior methods in terms of security and reliability.