Digital Watermarking and Its Applications Chair Professor Chin-Chen Chang Feng Chia University National Chung Cheng University National Tsing Hua University http://msn.iecs.fcu.edu.tw/~ccc http://msn.iecs.fcu.edu.tw/

Watermarking Image authentication Secret sharing Visual cryptography Steganography

Watermarking Visible watermarking Easy to embed Clear to see watermark

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

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

Secret sharing Classification: Meaningless shadows Meaningful shadows

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

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

Visual cryptography Stacking Shadow 1 Shadow 2 Secret

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

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

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

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

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

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

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

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

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

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

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

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

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

Steganography (Cont.) Image Hiding system Stego image Cover image Secret message Stego image 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0

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

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

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 …

Zhang and Wang’s Method (Embedding) 8 7 9 4 79 54 55 11 20 21 12 24 10 Secret data: 1000 1011… 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

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

Sudoku A logic-based number placement puzzle

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)

Data Hiding Using Sudoku - 1 Reference Matrix M

Data Hiding Using Sudoku (Embedding) (Cont.) 8 7 11 12 79 54 55 20 21 24 10 9 Secret data: 011 001 10… 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

Data Hiding Using Sudoku (Embedding) (Cont.) 8 7 11 12 79 54 55 20 21 24 10 9 Secret data: 011 001 10… 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

Data Hiding Using Sudoku (Extracting) (Cont.) 9 7 14 Stego Image Extracted data: 279 = 011 0012

Experimental Results

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

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

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

Information hiding in hypertext <HTML> </HTML> 0110 <body <p Secret: 010110… 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

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: 010110… 40 40

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

Text steganography in chat SMS-Texting 42

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

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

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

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