Watermarking and Steganography

1. Watermarking and Steganography

2. Watermarks • First introduced in Bologna, Italy in 1282 • Dandy Roll presses pattern into drying paper • Changes thickness of paper fibers • Uses: • By paper makers to identify their product • Security for stamps, official documents. • Stock certificates, money, etc. • Chic • Other “watermarks” • Printing on plastic with a window.(Australian $10 note)

3. Pressed into paper during paper-making process Dandy Roll • J. Plank Features • In-house watermark design • Computerized design process • Quick-change sleeves and sections               • Dandy roll • 7.25" diameter • Watermarking possible http://www.uwsp.edu/papersci/PM/Machine/Dandy.htm

4. Dandy Roll • High grade stainless steel construction • Incorporates internal oscillating shower, internal pan, internal steam shower and external saveall pan • Extended Header Brush for easy cleaning of shower pipe • Wet pulp sprayed onto moving belt • Dandy Roll pressed into pulp • Dandy Roll looks like oversized printer’s roll covered with pattern

5. Laser Printed “Watermarks” • Used on bond paper, but who uses bond paper? • Doesn’t work well in inkjets or laserjets • “Watermarks” with most print drivers…

6. Printed Watermarks • Looks great • You can even put it in your PDF file…which is the problem! • No security

7. Printed Document Authentication Techniques • Microprinting – Print that is too small to produce or copy with conventional equipment • Intaglio –engraved pattern used to press ink with great force; raised letters • Letterpress – Ink rolled raised type, leaving depression. Used for printing numbers. • Simultan press – precise registration of front and back. (see-through register). Changing ink colors (rainbowing). • Optically variable inks (change color depending on angle) • Metal foils & threads embedded in paper • Security holograms

8. Lessons for paper authentication • Security features should convey a message relevant to the product. • Use iridescent ink to print the banknote denomination • Should obviously belong where they are • They become “embedded in the user’s cognitive model.” • Should be obvious • Should not have competitors • Should be standardized Source: Security Engineering, Anderson

9. Information Hiding • Copyright Marks: • Watermarks - Hidden copyright messages • Fingerprints – Hidden serial numbers • Steganography • Hidden messages. • Other applications: • Closed captioning (hidden in first 21 scan lines) • http://www.robson.org/gary/writing/nv-line21.html • Audio RDS (Radio Data Service)-like service • “What’s that song?”

10. Watermarks for Copyright Policy • “never copy” • “copy only once” • “copy only at low quality” JPMG Linnartz, “The ‘Ticket’ Concept for Copy Control Based on Embedded Signaling” (Anderson [504] ) Suggests a hash-based implementation of “copy only once:” • X is the ticket • Record h(h(X)) on DVD • Provided with X, DVD recorded stores h(X) on second-generation copy.

11. The Broadcast Flag • “Advanced Television Systems Committee Flag” • Enable/Disable: • high-quality digital output • Re-transmitting on an “unprotected” channel • In the future: • Time-shifting? • Disallow fast-forward through commercials • Required on all digital TV cards sold after July 2005 • Only broadcast, not satellite or cable-transmitted. “Losing Control of Your TV,” Technology Review, March 3, 2004 http://www.technologyreview.com/articles/04/03/wo_garfinkel030304.asp?p=1

12. Steganography • A hidden message that can't be found by humans • A hidden message that can't be found by an algorithm. A hidden message that can be found by an algorithm but not by a human. • A hidden message that can be found by some algorithms but not others.   [Wayner 2004]

13. What is Hidden? Defining "Hidden" is not easy • We run into the usual Goedel limits that prevents us from being logical about detection. • Humans are very different. Somemusicians have very, very good ears. • Some algorithms leave statistical anomalies. Themessage is often more random than the carriersignal. These statistics can give away the message.

14. Who wants it? • Evil doers. If evil messages can't be seen by good people, evil will triumph. Osama bin Laden? • Good doers. If the good guys can communicate in secret, then goodwill triumph. U.S. forces • Content owners and copyright czars. Hidden messages can carry information about rights to view, copy, share, listen, understand, etc. • Software Developers. "Hidden" channels can be added to data structures without crashing previous versions. Steganography can fight bit rot.

15. Models for Steganography • Replace random number generators with the message. • This works if the random numbers are used in a detectable way. • TCP/IP, for instance, uses a random number for connections. Some grab this for their own purposes. • Replace noise with the message. • Just replace the least-significant bit. • Avoid the noise and tweak the salient features. • Anything not affected by compression. • If you have the freedom to change data without hurting the data, then you have the freedom to include another message.

16. Models for Steganography • Structured Models • Run some compression algorithm in reverse • If the compression models the data accurately, then running it in reverse should spit out something that models the data well. • Huffman algorithms give common letters short bit strings and rare ones long ones. • Change the structure or the order. • GifEncoder, for instance, changes the order of the colors in the palette. • Synthesize something new and use the data to guide the synthesis. • Is the ghoul shooting at you in the game using a revolver or a machine gun? That's one bit.

17. Noise • The least significant bit of pixels or sound files is very popular. • Tweaking the LSB is only a small change. Less than 1%. • 140=10001100 • 141=10001101 • You can encrypt, too! LSB modified to hide info

18. LSB Modification • Side Effects: • The data may not have the same statistical pattern as the least significant bits being replaced. • Add a lot of noise, and it’s obvious 4 LSB modified produces banding

19. More LSB Modification 6 bits 7 bits

20. 8 out of 8 bits All 8 bits Bit 8 vs. Bit 1

21. Wayner Demos • Information hiding at the bit level: • http://www.wayner.org/books/discrypt2/bitlevel.php • Encoding information through list order: • http://www.wayner.org/books/discrypt2/sorted.php#note2

22. JPEG Watermarking “Hide and Seek: An Introduction to Steganography” IEEE Security & Privacy Figure 2. Embedded information in a JPEG. (a) The unmodified original picture; (b) the picture with the first chapter of The Hunting of the Snark embedded in it.

23. Mesh Watermarking • Robust mesh watermarking, Emil Praun, Hugues Hoppe, Adam Finkelstein,July 1999Proceedings of the 26th annual conference on Computer graphics and interactive techniques

25. Issues to evaluate • “Capability” • Payload carrying ability • Detectability • Robustness • Securing information: Capacity is the wrong paradigm, Ira S. Moskowitz, LiWu Chang, Richard E. Newman , September 2002 Proceedings of the 2002 workshop on New security paradigms

26. SDMI – Secure Digital Media Initiative • SDMI (200+ companies) published an “Open Letter to the Digital Community” with an SDMI Challenge. • Earn up to $10,000 for breaking their “watermarks” • Challenge from September 15, 2000 – October 7, 2000 • SDMI Systems: • Designed to prevent “remixing” of privated CDs • Designed to survive MP3 compression

27. SDMI & The Academics • The Academics: • Scott Craver, Patrick McGregor, Min Wu, Bede Liu, (Dept. of Electrical Engineering, Princeton University) • Adam Stubblefield, Ben Swartzlander, Dan S. Wallach (Dept. of Computer Science, Rice University) • Edward W. Felten (Dept. of Computer Science, Princeton University) • What they did: • Successfully removed the digital watermark from the challenge audio samples. • How did they know they did it? • SDMI provided an “Oracle” that told them they did!

28. SDMI & Academics: Part 2 • Academics couldn’t claim cash prize • Doing so would have required signing a “confidentiality agreement” and prohibit the academics from sharing results with the public • DMCA didn’t apply… • … because SDMI specifically invited the work • Felton &c decided to present their findings at the 4th International Information Hiding Workshop April 25-29, 2001 • April 9, 2001 RIAA Senior VP for Business and Legal Affairs sent Felton letter with veiled DMCA threats • April 26, 2001 Felton declines to present paper • May 3, 2001 – RIAA and SDMI say they never intended to sue • June 6, 2001 – Felton files suit against RIAA asking for a declaratory judgment that they would not be infringing • November 28, 2001 – Case dismissed for mootness

29. Leading provider of watermarking technologies Plug-ins for Windows, PhotoShop, etc. Communicates: Copyright ownership Image ID Image content – adult, etc. DigiMarc

30. Tools and References • Fabien a. p. penticolas • http://www.petitcolas.net/fabien/steganography/ • Digimarc • http://theargon.com/archivess/steganography/ • Hiding Secrets with Steganography, by Dru Lavigne, • http://www.onlamp.com/pub/a/bsd/2003/12/04/FreeBSD_Basics.html • http://www.outguess.org

31. “Mosaïc attack” • Defeat an embedded watermark by chopping up image and serving it in pieces <nobr><img SRC="kings_chapel_wmk1.jpg’ BORDER="0’ ALT="1/6’ width="116’ height="140"><img SRC="kings_chapel_wmk2.jpg’ BORDER="0’ ALT="2/6’ width="116’ height="140"><img SRC="kings_chapel_wmk3.jpg’ BORDER="0’ ALT="3/6’ width="118’ height="140"></nobr><br><nobr><img SRC="kings_chapel_wmk4.jpg’ BORDER="0’ ALT="4/6’ width="116’ height="140"><img SRC="kings_chapel_wmk5.jpg’ BORDER="0’ ALT="5/6’ width="116’ height="140"><img SRC="kings_chapel_wmk6.jpg’ BORDER="0’ ALT="6/6’ width="118’ height="140"></nobr>

32. Mosaïc assembled • Some websites use mosaics to deter casual copying!

33. MP3Stego • Hides information in MP3 files during the compression process • Takes advantage of the fact that MP3 provides high-quality compression of 11:1 • Plenty of room for information hiding! • Randomly chooses which parts of the Layer III inner loop to modify; makes sure modifications don’t exceed threshold defined by the psycho acoustic model. • “Weak but better than the MPEG copyright flag defined in the standard” • Defeat by decompressing & recompressing

34. MP3Stego in action http://www.petitcolas.net/fabien/steganography/mp3stego/index.html

35. Translucent Databases (More Wayner Work, if we have time…)

36. Translucent Database • Instead of: • INSERT INO purchases values (“bob jones”, 55424, “36”, NOW()) • Use: • INSERT INTO purchases values (MD5(“bob jones”, 55424, “36”, NOW())

37. TD’s with Redundency • INSERT INTO salaries2 VALUES (MD5(“Fred Smith/1313 Mockingbird Lane/06-01-1960/012-34-5678”), MD5(“Fred Smith/1313 Mockingbird Lane/012-34-5678”), MD5(“Fred Smith/1313 Mockingbird Lane/06-01-1960”), MD5(“Fred Smith//06-01-1960/012-34-5678”), 60000, 5 20)

38. Coordinating Users

39. Inserting into multi-user table • INSERT INTO bboard1 Values(MD5(“Lucy”),MD5(“Ricky”),”You’ve got some explaining to do.”) • INSERT INTO bboard1 Values(MD5(“Lucy”),MD5(“Ricky”),ENCRYPT(”You’ve got some explaining to do.”))