Digital Watermarking

1. Digital Watermarking Thái Chí Minh Trần Lương Khiêm

2. Content • Introduction • History • Applications • Requirements • Techniques • Attacks

3. Content • Introduction • History • Applications • Requirements • Techniques • Attacks

4. Introduction 499.99 = 0.99

5. Introduction

6. Introduction Digital watermarking Steganography

7. Introduction Digital watermarking Relation between embedded message and cover work Goal and assumption Steganography

8. Content • Introduction • History • Applications • Requirements • Techniques • Attacks

9. History Fabriano Histiæus & the slave Paper watermark, 1282 Banknote. 18th century

10. History • In 1954, Emil Hembrooke of the Muzak Corporation filed a patent for watermarking” musical Works • The first Information Hiding Workshop (IHW) ,which included digital watermarking as one of its primary topics, was held in 1996

11. Content • Introduction • History • Applications • Requirements • Techniques • Attacks

12. Applications • Broadcast monitoring • Owner identification • Proof of ownership • Transaction tracking • Content authentication • Copy control

13. Broadcast monitoring Advertisement Rebroadcasting

14. Owner identification Original Lena Soderberg, 1972

15. Proof of ownership Bob Alice

16. Transaction tracking

17. Transaction tracking

18. Content authentication • Digital signature is NOT enough

19. Content authentication

20. Copy control • Cryptography is NOT enough

21. Copy control

22. Content • Introduction • History • Applications • Requirements • Techniques • Attacks

23. Requirements • Perceptual Transparency • Robustness • Data payload • With / Without originals • Security

24. Perceptual Transparency

25. Robustness • Fragile • Semi-fragile • Robust

26. Data payload • Data payload refers to the number of bits a watermark encodes within a unit of time or within a Work • Different applications may require very different data payloads

27. With / Without originals • Non-blind watermarking • Type I • Type II • Semi-blind watermarking • Blind watermarking

28. Security (Present later)

29. The mutual dependencies among the elements

30. Content • Introduction • History • Applications • Requirements • Techniques • Attacks

31. Techniques • LSB • Spread spectrum • Applying on Vietnamese documents

32. Techniques

33. Techniques • There are many techniques to do watermarking in digital things: • Spatial domain watermarking: LSB, in text data, … • Transform domain watermarking: frequency-based watermarking, wavelet based watermarking • Embedding the watermark in the transform domain from carrier object (using DCT, DFT, DWT, …)

34. Techniques • LSB: • Embedding: • Choosing some representation values (e.g pixels) of carrier object. • Embed the bits of message (watermark) to LSBs of representation value • Message ‘A’: 100 0001 • Carrier object: RGB (2 bits) 100000 010101 101100 010001 100001 000100 101110 011010 111000

35. Techniques • LSB: • Embedding: • Choosing some representation values (e.g pixels) of carrier object. • Embed the bits of message (watermark) to LSBs of representation value • Message ‘A’: 100 0001 • Carrier object: RGB (2 bits) 100001 010100 101100 010000 100001 000100 101111 011010 111000

36. Techniques • LSB: • Detector: • Retrieve the watermark by having the knowledge of the representation values (e.g pixels) used for embedding individuals bits

37. Techniques • Spread spectrum • Using frequency domain transform to convert the input image into another domain and embedding the watermark to this domain.

38. Techniques • Apply on Vietnamese documents

39. Techniques • Apply on Vietnamese documents

40. Techniques • Apply on Vietnamese documents • Besides, we can use some methods: • Vertically shifting text lines • Horrizontally shifting words

41. Content • Introduction • History • Applications • Requirements • Techniques • Attacks

42. Attacks • From processing • From attackers

43. Attacks • The actions take effect on the watermark embedded in carrier objects. • Affects: • Destroying the watermark or modifying the watermark with new wrong information. • Removing the watermark entirely. • But: not degrading the quality of carrier objects (image, audio, video) • Relating to a requirements of watermarking: Robustness

44. Attacks • Classification: • From proscessing carrier objects • Common signal processing: digital-to-analog and analog-to-digital conversion, or change image contrast, color, JPEG compression, … • Common geometric distortions: scaling, rotating, cropping, dithering … • From attacker • Mosaic • Collusion attacks: get the watermark or remove watermarks entirely to get the original work. • …

45. Attacks

46. Attacks Mosaic attack

47. Attacks • How to protect watermarks from attacks • Understanding and applying new researchs in watermarking • Using StirMarkBenchmark evaluation engine to evaluate your watermarking scheme • “All vendors of digital watermarks have their products benchmarked by Stirmark and as of August 2001, no watermark from any vendor survives the test, ie: the watermarks are all removed without degradation to image quality occurring. “

48. Questions & Answers Thank you