Out of site… Out of Mind

By Fred A. DuBrock COSC-356 Steganography

Derived from the Greek words steganos, which means “covered,” and graphia, which means “writing.”

Steganography Messages hidden in pictures (low order bits) Hard to detect that a message is even there! Difficult problem with respect to terrorism…

Steganography (Hidden Writing) A technique to prevent an opponent from reading your traffic and for him to remain unaware that there is any traffic at all. Old examples of this: * In ancient Greece tattooing on a slaves head * invisible ink * microdot * low-bandwidth applications

Steganorgraphy Steganography Practice of hiding information within other information Digital watermarks Hidden within documents and can be shown to prove ownership

How Steganography Is Used  Enhanced Data Structures  Strong Watermarks  Document Tracking Tools  Document Authentication  Private Communications

Strong Watermarks  Creators of digital content such as books, movies and audio files  A message may be inserted “This file copyright 2002 by Big Fun”  Some watermarks are meant to be found  Other watermarks are deliberately made as fragile as possible

Document Tracking Tools  Hidden information can identify the legitimate owner of a document  Is an idea attractive to both content- generating industries and government agencies with classified information

Private Communications  Useful in political situations when communications is dangerous

Steganalysis and watermark security What is steganalysis? Steganalysis is the art of discovering and rendering useless covert message, i.e., methods countering steganography. Note that the two goals with steganalysis: 1) Discover the presence of the secret message embedded in cover Work. 2) Make the secret message invalid.

However, steganographic watermarking needs to be secure against any steganalysis tools to detect watermarks’ presence. It is easily seen that --- in steganographic watermarking, watermarks’ presence must not be detected (resisting to unauthorized presence detection); while in non-steganographic watermarking, watermarks’ can be publicly announced.

Steganography-Practice of Hiding information in other information Example of a conventional watermark

Other References Digital Watermarking: ISBN Investigator's Guide to Steganography ISBN: Information Hiding Techniques for Steganography and Digital Watermarking ISBN:

Software Many useful programs can be found in Internet archives. Some of the better ones include the following: * * uk/~-fapp2/steganography * * html * isse.gmu. eduF~njohnson/Steganography * * * Specific software packages available on the Internet are listed here. Romana Machado distributes the Java ver- sion of her Stego and EzStego software from here. This cross-platform tool hides information in the least significant bit of an image after the colors in the image are sorted. This usually works quite well, but there can be some inconsistencies. See Sections 9.2 and The software is distributed with the GNU Public License.

Thanks. © 2004 Fred A. DuBrock