A robust coverless image-synthesized video steganography based on asymmetric structure

Due to the ability of hiding secret information without modifying image content, coverless image stegonagraphy has gained higher level of security and become a research hot spot. However, in existing methods, the issue of image order disruption during network transmission is overlooked. In this paper, the image-synthesized video carrier is proposed for the first time. The selected images which represent secret information are synthesized to a video in order, thus the image order will not be disrupted during transmission and the effective capacity is greatly increased. Additionally, an asymmetric structure is designed to improve the robustness, in which only the receiver utilizes a robust image retrieval algorithm to restore secret information. Specifically, certain images are randomly selected from a public image database to create multiple coverless image datasets (MCIDs), with each image in a CID mapped to hash sequence. Images are indexed based on secret segments and synthesized into videos. After that, the synthesized videos are sent to the receiver. The receiver decodes the video into frames, identifies the corresponding CID of each frame, retrieves original image, and restores the secret information with the same mapping rule. Experimental results indicate that the proposed method outperforms existing methods in terms of capacity, robustness, and security.