Rate-Distortion Theory of Robust Adaptive Steganographic Coding

As an important technique to achieve covert communication, steganography has developed greatly in pursuit of the secrecy of concealment suggested by Shannon. The most widely used scheme is called adaptive steganography which is composed of two phases: the distortion calculation phase and the adaptive steganographic coding phase. Conventionally, adaptive steganography assumes a noise-free lossless channel between the sender and the receiver. However, in real-world applications, the stego (cover media with secret messages embedded) would suffer from various lossy operations and be modified during transmission, leading to extraction error at the receiver. In this paper, robust adaptive steganographic coding is considered. We formalize the problem to be a problem of finding the maximum embedding rate of a special communication system with a normalized adaptive distortion function and a non-stationary memoryless sequence of discrete channels such that the secret message can be communicated without error. The theoretical rate-distortion bound of the problem is established which is a great leap forward in the research field of robust steganography. By modeling the noisy channels in real-world applications into non-stationary discrete memoryless channels (DMCs), our bound can be used to evaluate the existing robust methods and will serve as the ultimate goal for the design of new practical robust adaptive steganographic coding algorithms.

Submitted, IEEE Journal on Selected Areas in Communications