Introduction to Steganography

1. Introduction to Steganography • BSIT-7th • Instructor: Inam Ul Haq • Inam.bth@gmail.com Steganography, Network Security, University of Okara

2. Table of content • Information Hiding • Steganography • History • Fields applied to Information Hiding • Basic Terminologies • Steganalysis • Some Applications • Some Tools • Steganography Techniques Steganography, Network Security, University of Okara

3. Information Hiding F. A. P. Petitcolas, R. J. Anderson, M. G. Kuhn, “Information Hiding – A Survey”, Proceedings of the IEEE, special issue on protection of multimedia content, 87(7):1062-1078, July 1999 Steganography, Network Security, University of Okara

4. Information Hiding • Information Hiding is a branch of computer science that deals with concealing the existence of a message • It is related to cryptography whose intent is to render messages unreadable except by the intended recipients • It employs technologies from numerous science disciplines: • Digital Signal Processing (Images, Audio, Video) • Cryptography • Information Theory\Coding Theory • Data Compression • Human Visual/Auditory perception • There are four primary sub-disciplines of Information Hiding • Steganography • Watermarking • Covert Channels • Anonymity Steganography, Network Security, University of Okara

5. Steganography • Steganography means “covered writing” • A Greek word steganos means covered, protected or concealed • Definition: It is concealing any file, image, audio or video within another file. • Most frequently, steganography is applied to images, but many other data or file types are possible • Audio • Video • Text • Executable programs • Links Steganography, Network Security, University of Okara

6. History • The concept of message hiding is not new – it’s been around for centuries • A Greek shaved the head of a slave, wrote a message, then waited for the hair to grow back before sending the slave to his destination • Steganography (in the form of invisible ink) was used by Washington in the Revolutionary War • Prior to the Civil War, quilts were sewn with special patterns to tell escaping slaves which direction to go and what to do • In the 1980’s, some of Margaret Thatcher’s cabinet documents were leaked to the press. She ordered that the word processors being used by government employees, encode their identity in the word spacing of the documents Steganography, Network Security, University of Okara

7. Fields Applied to Information Hiding • Information Theory/Coding Theory • Digital Signal Processing • Discrete Fourier Transform/Discrete Cosine Transform • Image/Audio/Video Processing • Data Compression • Cryptographic Principles • Discrete Math • Cryptographic Hashing • Data Networks • The Human Visual System/Human Auditory System • Capabilities and limitations Steganography, Network Security, University of Okara

8. Basic Terminology • The data to be hidden: • Plaintext / Secret message / Stego-message / Embedded data • The data which will have a stego-message embedded in it: • Covertext / Cover-Object / • Cover-Image\Cover-Audio\Cover-Video • Target file • The key used to make the stego-message secure • Stego-Key / Secret Key / Key • The file with the steganography-message embedded • Stegotext / Stego-Object / • Stego-Image\Stego-Audio\Stego-Video Steganography, Network Security, University of Okara

9. Watermarking • Watermarking is very similar to steganography in that one of its goals is to not be detected • It’s primary goal is to not be able to be extracted or destroyed (at least not without destroying the cover too) • Typically, watermarking is designed to protect intellectual property rights for images, sounds, and video • If it’s easily removed or destroyed, those rights cannot be protected • There is a popular program called StirMark which does just that • Make it tamper proof Anonymity Anonymity is about concealing the sender and receiver of messages and this is the least studied sub-discipline of information hiding Steganography, Network Security, University of Okara

10. Steganalysis • Steganalysis is the detection of data that has been hidden • It is a cat and mouse game – as one group of researchers come up with better ways to hide stuff, another group figures out how to detect it or perhaps just destroy it Steganography, Network Security, University of Okara

11. Applications of Information Hiding • Covert military communications • Covert police communications • Criminals have learned that police are nearby when they hear encrypted communications, so they reduce their activity for the moment • A steganographic system would prevent this detection • Digital Rights Management – protecting intellectual property such as images, music, electronic books, etc. • Embedding textual data in medical images would better ensure that the picture belongs to a particular patient • This technique could apply to personal pictures, sounds, and movies • Tamper proofing – ensuring a data file has not been changed Steganography, Network Security, University of Okara

12. Steganography tools • Anubis • BMP Secrets • DarkCryptTC • OpenPuff • OpenStego • StegFS • StegoShare • Other tools: https://en.wikipedia.org/wiki/Steganography_tools • 12 best steganography tools: http://www.topbestalternatives.com/best-steganography-software/ Steganography, Network Security, University of Okara

13. Steganography tools (contt.) StegoShare allows embedding of large files into multiple images Steganography, Network Security, University of Okara

14. Steganography tools (contt.) Free tool that implements three layers of hidden data Steganography, Network Security, University of Okara

15. Steganographic Techniques - Substitution • The most common method is to replace the Least Significant Bit (LSB) in substitution • RSA Algorithm • Hash LSB • DEF CON 16 • See other techniques: https://pdfs.semanticscholar.org/8946/d2ea49e2ca7c53c157bfe09c2b656fc841ce.pdf Steganography, Network Security, University of Okara

16. Exercise 1- What is covert Channel? 2- Write a detail note on Anonymity. 3- Watermarking 4- Fingerprinting 5- Explore StirMark 6- What are different steganographic techniques? 7- Can you embed secret message into image? Steganography, Network Security, University of Okara