Secret Hiding and Retrieval Techniques for Digital Media 機密訊息在數位媒體中的隱藏及擷取技術之研究 Advisor: Chin-Chen Chang1, 2 Student: Yi-Hui Chen2 1 Dept. of Information Engineering and Computer Science, Feng Chia University 2 Dept. of Computer Science and Information Engineering, National Chung Cheng University

Outline Part I: Secrets Hiding for Digital Images Image Steganography LSB-based High-Capacity Data Embedding Scheme for Images Part II: Secrets Hiding for Compression Codes Joint Coding and Embedding Techniques for Multimedia Images

Part I : Secrets Hiding for Digital Images LSB-based High-Capacity Data Embedding Scheme for Images

Image Steganography ‧Quality, Capacity and Secrets Secrets Sender Internet Sender ‧Steganography - Prison Problem ‧Quality, Capacity and Security Secrets Receiver

Prison Problem Escape Alice Bob Warden

Zhang and Wang’s Method Hiding capacity = log2(2n+1) ≒ 2.32

Proposed Scheme (1/5) n = 2 Hiding capacity = log2(3n) ≒ 3.17

Steganography (2/5) n=2 a1 a2 50 51 F(50, 51)=50×1+51×3 mod 9 = 5 1 S = 3, 2 (0≦ S <3n) p=(3-5+(9-1)/2) mod 9 =2 p=(2-3+(9-1)/2) mod 9 =3

Steganography (3/5) a1 a2 50 51 51 50 1 50+(1) = 51 51+(-1)= 50 1 50+(1) = 51 51+(-1)= 50 Minus (1)3(1)3 p=2=(02)3 (-11)3 0+(-1)=-1 1+(0)=1 Minus (1)3(1)3 p=3=(10)3 (0 -1)3

Steganography (4/5) a1 a2 51 50 1 a1 a2 51 50 1 1 F(1, 1)=1×1+1×3 mod 9 = 4 p=(2-4+(9-1)/2) mod 9 =2 1+(1)=2 Minus (1)3(1)3 p=2=(02)3 (-1 1)3 1+(-1)=0 a1 a2 51 50 2

Steganography (5/5) a1 a2 51 50 2 F(51, 50)=51×1+50×3 mod 9 = 3 F(51, 50)=51×1+50×3 mod 9 = 3 F(0, 1)=2×1+0×3 mod 9 =2

Experiments (1/4) [16] Chang, C. C. and Tseng, H. W., “A Steganographic Method for Digital Images Using Side Match,” Pattern Recognition Letters, Vol. 25, No. 10, pp. 1431-1437, 2004. [46] Mielikainen, J., “LSB Matching Revisited,” IEEE Signal Processing Letters, Vol. 13, No. 5, pp. 285-287, 2006. [58] Wang, C. M., Wu, N. I., Tsai, C. S. and Hwang, M. S., “A High Quality Steganographic Method with Pixel-Value Differencing and Modulus Function,” Journal of Systems and Software, Vol. 81, No. 1, pp. 150-158, 2008. [60] Wu, D. C. and Tsai, W. H., “A Steganographic Method for Images by Pixel-Value Differencing,” Pattern Recognition Letters, Vol. 24, No. 9-10, pp. 1613-1626, 2003.

Experiments (2/4) Guillermito, Chi-square Steganography Test Program, available at http://www.guillermito2.net/stegano/tools/index.html.

Experiments (3/3)

Experiments (4/4) p≦0.5 Fridrich, J., Goljan, M. and Du, R., “Detecting LSB Steganography in Color and Gray-Scale Images,” Magazine of IEEE Multimedia, Special Issue on Security, 8(4), pp. 22~28, 2001.

Part II : Secret Hiding for Compression Codes Joint Coding and Embedding Techniques for Multimedia Images

Introduction Information hiding Sender Receiver Compression code: 1000011010… Digital Image Secret data: 011 Reconstructed image Compression code 1000011010… Secret data: 011 17

Squared Euclidean distance VQ Squared Euclidean distance Vector Quantization (VQ) Overview: X i Reconstructed Image 512

Side Match VQ (SMVQ) Assumption: Neighboring pixel intensities in an image are pretty similar. Seed Block Residual Block

Codebook (512) State codebook (8) X = (81, 15, 53, 34, 51,?, ?, ?, 91, ?, ?, ?, 49,?, ?, ?) Codebook (512) State codebook (8)

Proposed scheme (1/3) THSMVQ Bit=0

Proposed scheme (2/3) var(L)+var(U) <THvar Clustering result Bit=0

Proposed scheme (3/3) Clustering result

Experiments (1/3) [9] Chang, C. C. and Wu, W. C., “A Steganographic Method for Hiding Secret Data Using Side Match Vector Quantization,” IEICE Transactions on Information and Systems, Vol. E88-D, No. 9, pp. 2159-2167, Sep. 2005. [33] Jo, M., and Kim, H. D., “A Digital Image Watermarking Scheme Based on Vector Quantisation,” IEICE Transactions on Information and Systems, Vol. E85-D, No. 6, pp. 1054-1056, 2002.

Scheme-1 Scheme-2

Bit rate (0.56 bpp) and the similar capacity (16 kilobits)

Further Works Secrets data hiding Other digital media No extra indicator need to store Other digital media Text-based document Audios

Thanks for your attention