1. Thái Chí Minh Trần Lương Khiêm 1

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

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

4. Introduction 4

5. 5

6. 6

7. Relation between embedded message and cover work Goal and assumption 7

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

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

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 10

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

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

13. Broadcast monitoring 13

14. Owner identification 14

15. Proof of ownership 15

16. Transaction tracking 16

17. Transaction tracking 17

18. Content authentication  Digital signature is NOT enough 18

19. Content authentication 19

20. Copy control  Cryptography is NOT enough 20

21. Copy control 21

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

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

24. Perceptual Transparency 24

25. Robustness  Fragile  Semi-fragile  Robust 25

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 26

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

28. Security 28

29. The mutual dependencies among the elements 29

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

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

32. Techniques 32

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, …) 33

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 34

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 35

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

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

38. Techniques Apply on Vietnamese documents 38

39. Techniques Apply on Vietnamese documents 39

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

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

42. Attacks  From processing  From attackers 42

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 43

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. ○ … 44

45. Attacks 45

46. Attacks Mosaic attack 46

47. Attacks  How to protect watermarks from attacks Understanding and applying new researchs in watermarking Using StirMark Benchmark 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. “ 47

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