1. A Secret Information Hiding Scheme Based on Switching Tree Coding Speaker: Chin-Chen Chang

2. Outline VQ image compression Watermarking Search order coding (SOC) Switching tree coding (STC)

3. VQ Image Compression

4. Image Index table Vector Quantization Encoder w h VQ Compression

5. Image Index table Vector Quantization Decoder w h VQ Compression

6. PSNR = 29.62 dB Accuracy rate 99.95% Watermarking

7. Finds the nearest pairs

8. Find d(CW 0, CW 8 ) > TH d(CW 13, CW 14 ) > TH Unused CW0, CW8, CW13, CW14 hide 1 hide 0 CW 1 CW 11,CW 2,CW 3 CW 4, CW 5 CW 6, CW 7 CW 15, CW 10 CW 12, CW 9

9. Index Table Unused CW0, CW8, CW13, CW14 Encode

10. Water mark: 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0 Index Table 1 1 0 001 0 1 11 1 0 0 CW 1, CW 2, CW 4, CW 5 CW 6, CW 7 CW 11, CW 3 CW 15, CW 10 CW 12, CW 9 hide 1hide 0 1 0 Water mark

11. Water mark: 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0 Index Table 1 1 0 001 0 1 11 1 0 0 CW 1, CW 2, CW 4, CW 5 CW 6, CW 7 CW 11, CW 3 CW 15, CW 10 CW 12, CW 9 hide 1hide 0 1 0 Water mark

12. Water mark: 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0 Index Table 1 1 0 001 0 1 11 1 0 0 1 0 Water mark

13. Search-Order Coding (SOC)

14. An example for indices of VQ

15. Search-Order Coding (SOC) Searched point Non-searched point

16. 31207 211 312078 3121187 353187 The compressing steps Search-Order Coding (SOC) P 1 = 1 00011111 Indicator P 2 = 1 11001111 P 3 = 0 00 … P 6 = 0 10 Compression codes = 100011111 111001111 000 …

17. Information hiding on the SOC codes The proposed scheme: - Information hiding: to embed secret data into host image - Steganography : t o embed secret data into host image and the interceptors will not notice the existence of secret data - Based on SOC

18. Information hiding on the SOC codes Main idea: Ex. receiver receives the compression codes : 010101101110110110011000011 SOC OIV (original index value) It means that the embedded secret data is “01100” if SOC is represented to hide “0” and OIV is represented to hide “1”.

19. Information hiding on the SOC codes Method: ex. A 3*3 index table: 123 1182131 230 31 3293032 If the secret data is “111110100”, then the hiding position of each bit will be in the raster scan order.

20. Embedding phase: Defined: “0”  embedded into SOC and “1”  embedded into OIV. SOC ====> there is nothing that needs to change for its compression codes hide “0” SOC ====> translate SOC into OIV (give up SOC coding and keep the OIV) hide “1” OIV ====> there is nothing that needs to change hide “1” OIV ====> translate OIV into SOC ex. hide “0” + OIV 11 (SOC) Information hiding on the SOC codes

21. Ex. compression codes are still OIV: 100010010 translate SOC into OIV : 000 => 100011110 translate OIV into SOC : 100100000 => 01100100000

22. Cost table (bits): Information hiding on the SOC codes

23. Security: For enhancing the security of our method, the position in the index table for hiding each bit of secret data can be determined by using pseudo random number generator, and the secret data can be encrypted by using traditional cryptography system such as DES or RSA in advance. Information hiding on the SOC codes

24. Experimental results

28. Switching tree coding (STC)

29. Switching-tree coding (STC) Sheu proposed the STC algorithm in 1999 Re-encode the index table the current index U L

30. Switching-tree coding (STC) If P = 7, then P = U P ’ = ‘ 11 ’ If P = 10, then P = L P ’ = ‘ 10 ’

31. If P = 14, then P = A in index (3) P ’ = ‘ 01 ’ || index (3) = ‘ 0100011 ’ If P = 17, then P ’ = ‘ 01 ’ || (17) = ‘ 0010001 ’

32. Information Hiding on the STC codes (IHSTC)

33. Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … Index table

34. Information Hiding on the STC codes (IHSTC) Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P ’ = ‘ 00 ’ ||(10) ‘ 00 ’ ||(25) ‘ 00 ’ ||(21) …‘ 00 ’ ||(17)

35. Information Hiding on the STC codes (IHSTC) Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P ’ = ‘ 00 ’ ||(10) ‘ 00 ’ ||(25) ‘ 00 ’ ||(21) …‘ 00 ’ ||(17) ‘ 10 ’

36. Information Hiding on the STC codes (IHSTC) Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P ’ = ‘ 00 ’ ||(10) ‘ 00 ’ ||(25) ‘ 00 ’ ||(21) …‘ 00 ’ ||(17) ‘ 10 ’ ‘ 10 ’ ‘ 00 ’ ||(128) …

37. Information Hiding on the STC codes (IHSTC) Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P ’ = ‘ 00 ’ ||(10) ‘ 00 ’ ||(25) ‘ 00 ’ ||(21) …‘ 00 ’ ||(17) ‘ 10 ’ ‘ 10 ’ ‘ 00 ’ ||(128) … ‘ 11 ’

38. Three binary connection tree

39. If U-length > L-length then Tree B If U-length < L-length then Tree C Otherwise Tree A Tree B Tree C

40. Experiment results Image size = 512*512, n = 3 and |H| = 1024

41. Image size = 512*512, n = 3 and |H| = 2048 Image size = 512*512, n = 3 and |H| = NSTC Experiment results

42. Image size = 512*512, n = 5 and |H| = 1024 Image size = 512*512, n = 5 and |H| = 2048 Image size = 512*512, n = 5 and |H| = NSTC