Patent ID: RE40477

Claim:
A method for detecting least significant bit (“LSB”) embedding of a message hidden in randomly scattered samples of an alleged cover image, comprising the steps of: dividing the alleged cover image into a plurality of disjoint groups of adjacent samples; defining a discrimination function that assigns a real number to each member of said plurality of disjoint groups, thereby capturing the smoothness of each of said groups; defining on said plurality of disjoint groups at least one invertible operation that comprises a permutation of sample values, whereby values of said samples are invertibly perturbed by a small amount; applying said discrimination function and said invertible operation to define in said plurality three types of sample groups, (R)egular, (S)ingular, and (U)nusable, each of said types being defined for both positive and negative operations; plotting both positive and negative R and S for said alleged cover image on an RS diagram; constructing four curves of said RS diagram and calculating their intersections by extrapolation; and determining the existence or nonexistence of a secret message from said intersections.