Robust Image Steganography against General Scaling Attacks

Qingliang Liu, Jiangqun Ni, Xianglei Hu

Abstract: Conventional image steganography is assumed to transmit the message, in the most securest way possible for a given payload, over lossless channels, and the associated steganographic schemes are generally vulnerable to active attacks, e.g., JPEG re-compression, and scaling, as seen on social networks. Although considerable progress has been made on robust steganography against JPEG re-compression, there exist few steganographic schemes capable of resisting scaling attacks due to the tricky inverse interpolations involved in algorithm design. To tackle this issue, a framework for robust image steganography resisting scaling with general interpolations either in std form with fixed interpolation block, or pre-filtering-based anti-aliasing implementation with variable block, is proposed in this paper. And the task of robust steganography can be formulated as one of constrained integer programming aiming at perfectly recovering the secret message from the stego image while minimizing the difference between cover and stego images and the embedding distortion between scaled cover and scaled stego images. By introducing a metric - the degree of pixel involvement (dPI) to identify the modifiable pixels in the cover image, the optimization problem above could be effectively solved using the branch and bound algorithm (B&B). Extensive experiments demonstrate that the proposed scheme could not only resist scaling attacks with various interpolation techniques at arbitrary scaling factors (SFs), but also outperform the prior art in terms of security between the cover and stego images by a clear margin. In addition, the application of the proposed method in LinkedIn against the joint attacks of scaling and JPEG re-compression also shows its effectiveness on social network in real-world scenarios.