A General Framework for Structural Steganalysis of LSB Replacement

There are many detectors for simple Least Significant Bit (LSB) steganography in digital images, the most sensitive of which make use of structural or combinatorial properties of the LSB embedding method. We give a general framework for detection and length estimation of these hidden messages, which potentially makes use of all the combinatorial structure. The framework subsumes some previously known structural detectors and suggests novel, more powerful detection algorithms. After presenting the general framework we give a detailed study of one particular novel detector, with experimental evidence that it is more powerful than those previously known, in most cases substantially so. However there are some outstanding issues to be solved for the wider application of the general framework.