1 Digital Watermarking and Its ApplicationsChair 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 areaTry 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 ReconstructingImage size: 512  512 Reconstructing (2,4)-threshold secret sharing scheme PSNR=24 dB

8 Secret sharing (Cont.) Reconstructing Secret image Hiding Stego-imageReconstructed 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 ProgressiveMeaningful 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.) -AuthenticationHacker 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 RestorationFrequency 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 imageSecret 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.) PropertyA 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 city3 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 hypertextSecret message Cover hypertext Embedding Stego hypertext Secret key Extraction Secret message 38

39 Information hiding in hypertext 0110 Secret: … 1 capital letters small letters 0 1 :the written states Tags text file 1 2 3 4 5 6