Steganalysis

This chapter deals with steganalysis. Steganalysis is the counterpart of steganography, as its goal is to detect the presence of hidden data. Steganography is the art of stealth communication. Its purpose is to make communication undetectable to hide the presence of communication. Steganalytic methods are divided into targeted steganalysis and blind steganalysis. Targeted methods address a specific embedding paradigm. They use certain statistics that indicate the presence of hidden data and estimate the number of embedding changes, and thus the embedded message length. Some targeted steganalysis are narrow and not extensible to other embedding types. Blind methods do not assume the knowledge of the embedding mechanism. Blind steganalysis is a meta-detection method, which can detect any steganographic method. Blind methods start by characterizing natural images in high-dimensional feature space and training a classifier to distinguish between cover and stegoimages. The chapter outlines the future and scope of blind steganalytic methods and concludes by analyzing the advantages and limitations of blind and targeted methods.