1. Digital Watermarking and Its Applications
Chair Professor Chin-Chen Chang
Feng Chia University National Chung Cheng University National Tsing Hua University

2. Watermarking
Image authentication
Secret sharing
Visual cryptography
Steganography

3. Watermarking
Visible watermarking
Easy to embed
Clear to see watermark

4. Watermarking (Cont.) Invisible watermarking Requirements:
Good visual quality of watermarked image
Robustness
Watermarking
Original image
Watermarked image
Watermark

5. Image authentication Requirements: Detect the tampered area
Try to restore the tampered area
Image
Tampered image
Detected image
Restored image

6. Secret sharing
Classification:
Meaningless shadows
Meaningful shadows

7. Secret sharing (Cont.) Sharing Shadow size: 256  256 Reconstructing
Image size: 512  512
Reconstructing
(2,4)-threshold secret
sharing scheme
PSNR=24 dB

8. Secret sharing (Cont.) Reconstructing Secret image Hiding Stego-image
Reconstructed secret image
Secret image
Stego-image
(2, n)-threshold secret
sharing scheme
Stego-image

9. Visual cryptography
Stacking
Shadow 1
Shadow 2
Secret

10. Visual cryptography (Cont.)
shadow1
cover image1
stego image1
shadow2
cover image2
stego image2

11. Visual cryptography (Cont.)
stego image1
stego image2
stacked result

12. Visual cryptography (Cont.)
shadow1
cover image1
stego image1
shadow2
cover image2
stego image2

13. Visual cryptography (Cont.)
stego image1
stego image2
stacked result

14. Visual cryptography (Cont.) -Meaningful and Progressive
Meaningful shares: friendly content
Progressive visual cryptography
Improve the stacked result progressively

15. Visual cryptography (Cont.) -Progressive Visual Cryptography (t, 6)
(2, 6)
(3, 6)
(4, 6)
(5, 6)
(6, 6)

16. Visual cryptography (Cont.) -Experimental Results
(2, 6)
(3, 6)
(4, 6)
(5, 6)
(6, 6)

17. Visual cryptography (Cont.)
Stacking
Shadow 1
Shadow 2
Secret

18. Visual cryptography (Cont.) -Authentication
Hacker 18
Visual cryptography (Cont.) -Authentication
Stack
Participant 1
Share 1
Recovered secret image
Original secret image
Participant 2
Share 2 18

19. Visual cryptography (Cont.)
Legal extra
confidential image
Legal revealed
secret image
Correct stacking result
Correct stacking result
Share 1
Share 1
Share 2
Share 2 19

20. Visual cryptography (Cont.)
Nothing
Tampered revealed
secret image
Tampered secret image
Tampered secret image
Tampered share 1
Tampered share 1
Share 2
Share 2 20

21. Visual cryptography (Cont.)
Rotating 40o
Stacking
Stacking
Share 1
Share 2
Secret 1 “VISUAL”
Secret 2 “SECRET”

22. Steganography The targets Restoration
Frequency domain (e.g. DCT, DWT, DFT)
Spatial domain (e.g. pixel values)
Compression domain (e.g. VQ)
Text
Restoration
Irreversible
Reversible

23. Steganography (Cont.) Image Hiding system Stego image Cover image
Secret message
Stego image

24. Steganography (Cont.) -Kim et al.’s Method： 9 1 2 3 4 5 6 7 8 …

25. Kim et al.’s Method (Embedding)5 8 3 4 7 6 1 2 ： 9 1 2 3 4 5 6 7 8
Cover Image
Cover Image 6 9 7 3 8 1 2 5 4 …
Stego Image
Stego Image

26. Kim et al.’s Method (Embedding)6 9 7 3 8 1 2 5 4 ： 9 1 2 3 4 5 6 7 8
Stego Image
Stego Image …

27. Zhang and Wang’s Method (Embedding)8 7 9 4 79 54 55 11 20 21 12 24 10
Secret data: … p2
255 1 2 3 4 1 2 3 4 1 : : : : : : : : : : : : :
10002
1 35 … 11 2 3 4 1 2 3 4 1 2 3 2 … 10 1 2 3 4 1 2 3 4 1
Cover image … 9 3 4 1 2 3 4 1 2 3 4 3 … 8 1 2 3 4 1 2 3 4 1 2 1 … 7 4 1 2 3 4 1 2 3 4 4 … 6 2 3 4 1 2 3 4 1 2 3 2 … 5 1 2 3 4 1 2 3 4 1 7 10 4 … 4 3 4 1 2 3 4 1 2 3 4 3 … 3 1 2 3 4 1 2 3 4 1 2 1 … 2 4 1 2 3 4 1 2 3 4 4 … 1 2 3 4 1 2 3 4 1 2 3 2 … 1 2 3 4 1 2 3 4 1
Stego image 1 2 3 4 5 6 7 8 9 10 11 …
255 p1
Magic Matrix

28. Zhang and Wang’s Method (Extracting)p2 7 10 4
255 1 2 3 4 1 2 3 4 1 : : : : : : : : : : : : : … 11 2 3 4 1 2 3 4 1 2 3 2 … 10 1 2 3 4 1 2 3 4 1 … 9 3 4 1 2 3 4 1 2 3 4 3 … 8 1 2 3 4 1 2 3 4 1 2 1
Stego image … 7 4 1 2 3 4 1 2 3 4 4 … 6 2 3 4 1 2 3 4 1 2 3 2 … 5 1 2 3 4 1 2 3 4 1 … 4 3 4 1 2 3 4 1 2 3 4 3 … 3 1 2 3 4 1 2 3 4 1 2 1 … 2 4 1 2 3 4 1 2 3 4 4
1 35 … 1 2 3 4 1 2 3 4 1 2 3 2 … 1 2 3 4 1 2 3 4 1 p1 1 2 3 4 5 6 7 8 9 10 11 …
255
Extracted secret data: 10002
Magic Matrix

29. Sudoku
A logic-based number placement puzzle

30. Sudoku (Cont.) Property
A Sudoku grid contains nine 3 × 3 matrices, each contains different digits from 1 to 9.
Each row and each column of a Sudoku grid also contain different digits from 1 to 9.
Possible solutions:
6,670,903,752,021,072,936,960
(i.e. ≈ 6.671×1021)

31. Data Hiding Using Sudoku
- 1
Reference Matrix M

32. Data Hiding Using Sudoku (Embedding) (Cont.)8 7 11 12 79 54 55 20 21 24 10 9
Secret data: …
279
Cover Image
min.
d( , ) = ((8-8)2+(4-7)2)1/2=3
d( , ) = ((9-8)2+(7-7)2)1/2=1
d( , ) = ((6-8)2+(8-7)2)1/2=2.24 9 7
Stego Image

33. Data Hiding Using Sudoku (Embedding) (Cont.)8 7 11 12 79 54 55 20 21 24 10 9
Secret data: …
279
Cover Image
d( , ) = ((11-11)2+(15-12)2)1/2=3
d( , ) = ((15-11)2+(12-12)2)1/2=4
d( , ) = ((9-11)2+(14-12)2)1/2=2.83
min. 9 7 14
Stego Image

34. Data Hiding Using Sudoku (Extracting) (Cont.)9 7 14
Stego Image
Extracted data: 279 =

35. Experimental Results

36. Steganography (Cont.) Text Video Sound 壞的毛病 壞毛病 山東的蘋果 山東蘋果 我的媽媽 我媽媽
壞的毛病 壞毛病
山東的蘋果 山東蘋果
我的媽媽 我媽媽
主要的問題 主要問題
另外的一件事 另外一件事
其他的問題 其他問題
北京的大學 北京大學
Video
Sound

37. Synonym substitution 0 wonderful 1 decent 2 fine Taichung is a 0 city
3 great
4 nice
Taichung is a
0 city
1 town
little
Secret message: (3)5(1)2
Taichung is a great little town 37

38. Information hiding in hypertext
Secret message
Cover hypertext
Embedding
Stego hypertext
Secret key
Extraction
Secret message 38

39. Information hiding in hypertext
<HTML>
</HTML>
0110
<body
<p
Secret: … 1
</title>
capital letters small letters
0 1
:the written states
Tags
text file 1 2 3 4 5 6
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=big5">
<title> 多媒體暨網路安全實驗室 </title>
</head>
<body bgcolor="#D27D1O">
<p align="center"><img border="0" src="msn.jpg" width="338" height="345"></p>
<p align="center"><font face="標楷體" color="#f4efe8" size="7">~歡迎加入~</font></p>
</body>
</html>
<META 39 39

40. Information hiding in hypertext
capital letters small letters
0 1
:the written states
text file 1 2 3 4 5 6
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=big5">
<title> 多媒體暨網路安全實驗室 </title>
</head>
<body bgcolor="#D27D1O">
<p align="center"><img border="0" src="msn.jpg" width="338" height="345"></p>
<p align="center"><font face="標楷體" color="#f4efe8" size="7">~歡迎加入~</font></p>
</body>
</html>
<HTML>
<META
<body
<p
</HTML>
Secret: … 40 40

41. Text steganography in chat
Shirali-Shahreza, M.H., Shirali-Shahreza, M., “Text Steganography in Chat,” Proceedings of the Third IEEE/IFIP International Conference in Central Asia on Internet the Next Generation of Mobile, Wireless and Optical Communications Networks, Tashkent, Uzbekistan, Sep. 2007, pp. 1-5. 41

42. Text steganography in chat
SMS-Texting 42

43. Text steganography in chat
Usual abbreviated words
univ.  university
PC  Personal Computer
M.S.  master of science
UN  United Nations
Dr  doctor 43

44. Text steganography in chat
SMS list + abbreviated words list
 Check list
0  full form, 1  abbreviated form 44

45. Text steganography in chat
Embedding :
“Please call me when you feel upset.”
secret “10”
“Please CM when you feel upset.”
Extracting :
Check list
secret bits “10” 45

46. Thanks for your listening