Shimmer: a Provably Secure Steganography Based on Entropy Collecting Mechanism

This paper introduces a practical and provably secure steganography scheme. Most of practical steganography methods alter the model distribution to conceal private messages, posing security risks. Prior theoretical approaches are grounded in unrealistic assumptions and are not efficiently applicable to real-world scenarios. The potential of practical and provably secure steganographic methods has not been fully realized. To address these challenges, we introduce a novel entropy collection mechanism designed to ensure security and increase capacity. This mechanism captures residual entropy from the previous embedding phase and utilizes it in subsequent embedding steps, thereby increasing embedding capacity. Leveraging this mechanism, we propose Shimmer, a practical and provably secure steganography method with high capacity. We apply an mitigation to minimize the probability of interval splitting events, which maximizes its capacity further. Our experimental results demonstrate that Shimmer achieves highest bitrate compared to other existing practical and provably secure steganography techniques.