1. Edward J. Delp Panasonic January 13, 2000 Slide 1 Watermarking: What is the Future? Edward J. Delp Purdue University School of Electrical and Computer Engineering Purdue Multimedia Testbed Video and Image Processing Laboratory (VIPER) West Lafayette, IN 47907-1285 +1 765 494 1740 +1 765 494 0880 (fax) email: ace@ecn.purdue.edu http://www.ece.purdue.edu/~ace

2. Edward J. Delp Panasonic January 13, 2000 Slide 2 Acknowledgements Students - –Eduardo Asbun –Dan Hintz –Paul Salama –Ke Shen –Martha Saenz –Eugene Lin –Ray Wolfgang –Greg Cook –Sheng Liu

3. Edward J. Delp Panasonic January 13, 2000 Slide 3 VIPER Research Projects Scalable Video and Color Image Compression –still image compression (CEZW) –high and low bit rate video compression (SAMCoW) –wireless video Error Concealment Content Addressable Video Databases (ViBE) –Scene Change Detection and Identification –Pseudo-Semantic Scene Labeling Multimedia Security: Digital Watermarking

4. Edward J. Delp Panasonic January 13, 2000 Slide 4 VIPER Research Projects Multicast Video Analysis of Mammograms Embedded Image and Video Processing

5. Edward J. Delp Panasonic January 13, 2000 Slide 5 Multimedia Security “Everything” is digital these days - a copy of a digital media element is identical to the original How can an owner protect their content? Are images still “fossilized light”? What does all of this mean in terms of law? Does any security system really work or does it just make us feel good!

6. Edward J. Delp Panasonic January 13, 2000 Slide 6 What Do We Want From a Security System? Access Control Copy Control Auditing (fingerprinting) –Who did what and when? Playback Control Record Control Generation Control 

7. Edward J. Delp Panasonic January 13, 2000 Slide 7 Digital Communication System

8. Edward J. Delp Panasonic January 13, 2000 Slide 8 Typical Cryptography System: Trusted Users Source User Insecure Channel Attacker Is this a pirate device?

9. Edward J. Delp Panasonic January 13, 2000 Slide 9 Cryptography System: User Not Trusted Source User Insecure Channel Authentication

10. Edward J. Delp Panasonic January 13, 2000 Slide 10 What is Watermarking? The use of perceptually invisible authentication techniques –“controlled” distortion is introduced in a multimedia element Visible watermarks also exists Is our community mesmerized by watermarking technology?

11. Edward J. Delp Panasonic January 13, 2000 Slide 11 Media Elements Audio Video Documents (including HTML documents) Images Graphics Graphic or Scene Models Programs (executable code)

12. Edward J. Delp Panasonic January 13, 2000 Slide 12 Scenario –an owner places digital images on a network server and wants to “protect” the images Goals –verify the owner of a digital image –detect forgeries of an original image –identify illegal copies of the image –prevent unauthorized distribution Watermarking Scenario

13. Edward J. Delp Panasonic January 13, 2000 Slide 13 Where are Watermarks Used? Watermarks have been used or proposed in: –digital cameras –DVD video –audio (SDMI) –broadcast video (in US - ATSC) visible watermarks now used –“binding” mechanism in image and video databases –key distribution systems –preventing forgery of bank notes Usually as secondary security  conversion to “analog”

14. Edward J. Delp Panasonic January 13, 2000 Slide 14 Steganography Steganography - (covered writing) techniques used to hide information within other information to conceal the very existence of the message Used much longer than cryptography Different than crytography in that an illegal user may intercept the message

15. Edward J. Delp Panasonic January 13, 2000 Slide 15 Multimedia Security Applications Privacy Forgery Detection  watermarking Copyright Protection  watermarking Proof of Purchase (non-deniable) Proof of Delivery (non-deniable) Intruder Detection

16. Edward J. Delp Panasonic January 13, 2000 Slide 16 Multimedia Security - Tools Set Encryption Authentication Hashing Time-stamping Watermarking

17. Edward J. Delp Panasonic January 13, 2000 Slide 17 Cryptographic Issues for Images Encryption protects image until decryption Authentication protects image ownership and content but does not conceal the image Time stamping verifies an image’s creation date, ownership and content Copy Detection vs. Authentication –copy detection identifies copies of an original image (possibly altered) –authentication determines who owns an image –an altered copy of an image would fail an authentication test

18. Edward J. Delp Panasonic January 13, 2000 Slide 18 Time Stamps Time stamps use hash functions to verify a digital work’s time of creation, ownership and content: –When was this data created or last modified? Two procedures: –certification - the author of the data can "sign" the record, or a user can fix data in time. The result is a certificate –verification - any user can check data and its certificate to make sure it is correct Time stamping is a form of authentication and requires a “trusted” third party escrow agent http://www.surety.com/

19. Edward J. Delp Panasonic January 13, 2000 Slide 19 Why is Watermarking Important?

20. Edward J. Delp Panasonic January 13, 2000 Slide 20 Why is Watermarking Important?

21. Edward J. Delp Panasonic January 13, 2000 Slide 21 Why Watermarking is Important?

22. Edward J. Delp Panasonic January 13, 2000 Slide 22 Why is Watermarking Important?

23. Edward J. Delp Panasonic January 13, 2000 Slide 23 Why is Watermarking Important?

24. Edward J. Delp Panasonic January 13, 2000 Slide 24 Why is Watermarking Important?

25. Edward J. Delp Panasonic January 13, 2000 Slide 25 Why is Watermarking Important?

26. Edward J. Delp Panasonic January 13, 2000 Slide 26 Why is Watermarking Important?

27. Edward J. Delp Panasonic January 13, 2000 Slide 27 A Overview of Watermarking Techniques Spatial watermarking Spatial Frequency (DCT or wavelet) watermarking Visible watermarks

28. Edward J. Delp Panasonic January 13, 2000 Slide 28 Components of a Watermarking Technique The watermark, W –each owner has a unique watermark The marking algorithm –incorporates the watermark into the image Verification algorithm –an authentication procedure (determines the integrity / ownership of the image)

29. Edward J. Delp Panasonic January 13, 2000 Slide 29 Main Principles Transparency - the watermark is not visible in the image under typical viewing conditions Robustness to attacks - the watermark can still be detected after the image has undergone linear and/or nonlinear operations (this may not be a good property - fragile watermarks) Capacity - the technique is capable of allowing multiple watermarks to be inserted into the image with each watermark being independently verifiable

30. Edward J. Delp Panasonic January 13, 2000 Slide 30 Attacks Compression Filtering Printing and rescanning Geometric attacks - cropping, resampling, rotation Collusion - spatial and temporal Conversion to analog

31. Edward J. Delp Panasonic January 13, 2000 Slide 31 DCT Coefficient Modulation Fixed-length DCT watermark Variable-length DCT watermark Scaling of spatial watermark in DCT domain

32. Edward J. Delp Panasonic January 13, 2000 Slide 32 Fixed-length DCT Watermark W is a sequence of random numbers –bipolar binary sequence, or N(0,1) X D and Y D are DCT of X and Y a = scaling factor:

33. Edward J. Delp Panasonic January 13, 2000 Slide 33 DCT Watermark W * is the extracted version of the watermark Verification: T = user-defined threshold If S > T, image is authentic

34. Edward J. Delp Panasonic January 13, 2000 Slide 34 Original Image

35. Edward J. Delp Panasonic January 13, 2000 Slide 35 Fixed-length DCT Watermark a = 0.1

36. Edward J. Delp Panasonic January 13, 2000 Slide 36 Fixed-length DCT Watermark a = 0.5

37. Edward J. Delp Panasonic January 13, 2000 Slide 37 Fixed-length DCT Watermark a = 1.0

38. Edward J. Delp Panasonic January 13, 2000 Slide 38 Fixed-length DCT Watermark a = 5.0

39. Edward J. Delp Panasonic January 13, 2000 Slide 39 Current Research Issues Theoretical Issues –capacity and performance bounds –models of the watermarking/detection process Robust Watermarks –linear vs. nonlinear –scaling and other geometric attacks –watermarking analog representations of content –new detection schemes –what should be embedded (watermark structure)

40. Edward J. Delp Panasonic January 13, 2000 Slide 40 Fragile Watermarks Are we asking too much from a robust watermark? –it is a very interesting signal processing/signal detection problem but will lead to a solution or an arms race Fragile watermarks do not have to worry about this!

41. Edward J. Delp Panasonic January 13, 2000 Slide 41 Legal Issues When one says: “My watermarking withstands the X attack!” –What does it mean? (Has the watermark been damaged?) –It is legally defensible? –Nearly all watermarks require statistical tests for verification

42. Edward J. Delp Panasonic January 13, 2000 Slide 42 Research at Purdue Fragile and semi-fragile watermarks for forensic imaging –are fragile watermarks better than hashing? Extending concept of robust image adaptive watermarks to video (with Chris Podilchuk) –is there a temporal masking model that works?

43. Edward J. Delp Panasonic January 13, 2000 Slide 43 VW2D Watermarked Image

44. Edward J. Delp Panasonic January 13, 2000 Slide 44 Image Adaptive Watermarks (DCT)

45. Edward J. Delp Panasonic January 13, 2000 Slide 45 Image Adaptive Watermarks (DCT)

46. Edward J. Delp Panasonic January 13, 2000 Slide 46 “Watermarking” Standards Data Hiding Subgroup (DHSG) of the Copy Protection Technical Working Group (CPTWG) –two groups have proposed systems for watermarking video used in DVD –watermark will be second level of security after encryption –the watermarks are relatively easy to defeat by difficult to remove

47. Edward J. Delp Panasonic January 13, 2000 Slide 47 Watermarking: Legal/Political Issues Watermarking technologies have not been tested in court –is watermarking the “feel good” technology of multimedia? Might one be better off just doing timestamping and/or other forms of authentication? What does it mean when a watermarking technique survives an attack (verification based on statistical tests) Watermarking may always be the secondary security method

48. Edward J. Delp Panasonic January 13, 2000 Slide 48 Ownership Copyright Ownership - Who did it first?  timestamp (prevents re-watermarking attacks)

49. Edward J. Delp Panasonic January 13, 2000 Slide 49 Unauthorized Distribution and Illegal Copies Unauthorized Distribution –You took my image from my web site! –You are selling my image from the CD-ROM you bought from me! Who owns it?  hash and timestamp Is your image the same as mine? (derived work)

50. Edward J. Delp Panasonic January 13, 2000 Slide 50 Digital Millennium Copyright Act It will be illegal to remove a watermark for a multimedia element http://lcweb.loc.gov/copyright/ http://www.dfc.org/

51. Edward J. Delp Panasonic January 13, 2000 Slide 51 Conclusions Watermarking is still an interesting research area with many interesting problems –will it be useful? (does it work?) –will watermarking only be used a second-tier security system? –will there be significant theoretical developments? Is watermarking the “feel good” technology of multimedia?

52. Edward J. Delp Panasonic January 13, 2000 Slide 52 Web Resources http://www-nt.e-technik.uni- erlangen.de/~hartung/watermarkinglinks.html

53. Edward J. Delp Panasonic January 13, 2000 Slide 53 Watermarking Conference Conference on Security and Watermarking of Multimedia Contents II (January 23-28, 2000) in San Jose http://www.spie.org/web/meetings/calls/pw00/confs/ ei23.html

54. Edward J. Delp Panasonic January 13, 2000 Slide 54 Reference R. B. Wolfgang, C. I. Podilchuk, and E. J. Delp, “Perceptual watermarks for digital images and video,” Proceedings of the IEEE, July 1999. Available at: ftp://skynet.ecn.purdue.edu/pub/dist/delp/watermark- proceedings/

55. Edward J. Delp Panasonic January 13, 2000 Slide 55 How I Spent My Summer