1. Recent Developments in Information Hiding
Chair Professor Chin-Chen Chang
National Tsing Hua University National Chung Cheng University Feng Chia 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.)
Stacking
Shadow 1
Shadow 2
Secret

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

12. 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

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

14. 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

15. 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 7 10 4 … 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 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

16. 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

17. Sudoku
A logic-based number placement puzzle

18. 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)

19. Data Hiding Using Sudoku
- 1
Reference Matrix M

20. 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

21. 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

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

23. Experimental Results

24. Thanks for your listening