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A new approach to reliable detection of LSB steganography in natural images

A new approach to reliable detection of LSB steganography in natural images. Sources: Signal Processing, Vol. 83, Issue 10, October 2003, pp. 2085-2093 Authors: Tao Zhang, Xijian Ping Speaker: Jui-Yi Kuo Date: 2004/06/12. Outline . Introduction LSB steganography Difference image histogram

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A new approach to reliable detection of LSB steganography in natural images

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  1. A new approach to reliable detection of LSB steganography in natural images Sources: Signal Processing, Vol. 83, Issue 10, October 2003, pp. 2085-2093 Authors: Tao Zhang, Xijian Ping Speaker: Jui-Yi Kuo Date: 2004/06/12

  2. Outline • Introduction • LSB steganography • Difference image histogram • The proposed Steganalysis • Conclusions

  3. LSB steganography Cover image Embedded Image Stego-image

  4. 20-35=(-15) Difference image histogram D(i,j)=I(i+1,j)-I(i,j) Difference image Difference image histogram Original image

  5. The proposed steganography i: different value between two pixel hi: amount of difference i generated by stego-image fi: amount of difference i generated by stego-image which is after flipping all bits in the LSB plane gi: amount of difference i generated by stego-image which is after setting all bits in the LSB plane to zero ai,j: transition coefficient from gi to hj

  6. Difference image histogram (Ex.) (a) Cover image (c) After flipping of cover image (b) Stego-image (d) After flipping of Stego-image

  7. 1 1 0 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 g g 2 1 0 1 gi : set to zero of LSB plane Difference = Even g g Difference = Odd

  8. 1 1 0 1 1 0 0 0 0 0 0 0 1 0 0 1 1 1 0 0 0 1 0 0 f 1 3 1 fi : flipping all bit of LSB plane Difference = Even f f 0 0 0 1 Difference = Odd f -1

  9. 8 6 g2i+2 0.5 0.5 0.25 0.33 a2i,2i+1 a2i,2i+3 a2i+2,2i+2 3 4 4 h2i+2 h2i+3 =0.5*8=4 =0.25*8+0.33*6=4 =0.25*8+0.17*6=3 Transition diagram a2i,2i-1+a2i,2i+a2i,2i+1=1 g2i a2i,2i-1 a2i,2i+1 a2i,2i h2i-1 h2i h2i+1 h2i=f2i=a2i,2i g2i h2i+1=a2i,2i+1 g2i+a2i+2,2i+1 g2i+2 f2i+1=a2i,2i-1 g2i+a2i+2,2i+3 g2i+2

  10. Transition coefficients a0,1=a0,-1=(g0-h0)/(2g0) a2i,2i=h2i/g2i a2i,2i-1=(h2i-1-a2i-2,2i-1 g2i-2)/g2i a2i,2i+1=1-a2i,2i-a2i,2i-1

  11. Transition coefficients (Ex.)

  12. Embedding Ratio 2d1*P2+(d3-4d1-d2)*P+2d2=0 P is embedding ratio

  13. Embedding Ratio (Ex.)

  14. Conclusions • detection of LSB steganography • Embedding ratio of an image with LSB steganography

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