NDCA: a neighboring block differences-based cost assignment method for robust video steganography on social networks

Social network-based covert communication conceals the communication link between the sender and receiver, enabling one-to-many communication. Videos, due to their rich content and high embedding capacity, are ideal carriers for steganographic techniques. However, social networks typically apply lossy processing to uploaded videos, presenting significant challenges in constructing reliable covert communication channels. While prior research has proposed robust video steganographic methods, these approaches often rely on synchronization of robust regions to correctly extract hidden data. A major challenge arises when synchronization information is altered during lossy processing, complicating the accurate extraction of hidden data. To address this, a robust video steganographic framework is proposed. We then analyze the factors influencing the robustness of embedding units, including neighboring block differences, modulation types, and rate control modes. Based on this analysis, we introduce the Neighboring block Differences-based Cost Assignment (NDCA) method. Extensive experiments are conducted to demonstrate that the proposed framework and NDCA enhance robustness against lossy processing while maintaining high steganographic security. Furthermore, the robust video steganographic techniques based on the proposed framework and NDCA are broadly applicable to commonly used video encoders and rate control modes, enabling reliable covert communication on mainstream social networks.