利用编码技术来隐藏秘密信息

1、利用編碼技術來隱藏秘密信息利用編碼技術來隱藏秘密信息Chair Professor Chin-Chen Chang (張真誠)n National Tsing Hua Universityn National Chung Cheng Universityn Feng Chia University .tw/ccc2IntroductionnInformation HidingCover imageHiding systemSecret messageStego image1 0 1 0 1 0 0 1 0 1 1 1 1 0 03Introducti

2、on (Cont.)nCover Carriers nImagenVideonSoundnText4Data: 1 1 0 1SenderReceiver1 1 1 1?. . . . . . . .Data: 1 0 1 0 1 0 11 0 1 0 1 1 1. . . . . . . .Corrected data:1 0 1 0 1 0 15(7, 4) Hamming CodingnEncodingData: 1 1 0 12p1 p2 d1 p3 d2 d3 d41 0 1 0 1 0 1d1 d2 d4 = p1 1 1 1 = 1d1 d3 d4 = p2 1 0 1 = 0d

3、2 d3 d4 = p3 1 0 1 = 0d1 d2 d3 d4Encoded dataEncodingp1 p2 d1 p3 d2 d3 d46(7, 4) Hamming Coding (Cont.)nError DetectionReceived data:1 0 1 0 1 1 1Error Position10100 0 0 1 1 11110 1 1 0 0 111601 0 1 0 1 010111Corrected data:1 0 1 0 1 0 1CorrectingParity check matrix HError bit(7, 4) Hamming Coding (

4、Cont.)The (7,4) Hamming code can be applied to data hiding based on the pixel domain and AMBTC domain. 7Matrix Coding Method8Example: 7,4 Hamming code, the parity check matrix H is :Embedding process: Cover vector Extraction process: Stego vector y = Change one bit in x according to coset leader ass

5、ociated to syndrome = Change one bit in x according to coset leader associated to = Change one bit in according to coset leader associated to = 0010100000111101100111010101H110m 1010100 x 110111001mHxSyndrome110mHy 100000000000100010000000010000010000100000001101010010000009Matrix Coding Method base

6、d on the pixel domain0001111011001110101010000101100001010000010010000011000000011000001000000110000001001000010111110963412911Cover ImageParity check matrix H(1010100)T = (1 1 1)TSecret data: 1 1 0 00 0 10000101000001010000010010000011000000011000001000000110000001001000010111010963412911Stego Imag

7、enEmbedding10Matrix Coding Method (Cont.) based on the pixel domain000111101100111010101(0010100)T = (1 1 0)TExtracted secret data: 1 1 0 00000101000001010000010010000011000000011000001000000110000001001000010111010963412911Stego ImagenExtracting 7 pixels embed 3 bitsMatrix Coding Method based on th

8、e AMBTC algorithmn 1124876496257249611812514456418297211114Matrix Coding Method based on the AMBTC algorithmnAMBTC algorithm (Absolute moment block truncation coding)1224876496257249611812514456418297211114100000011100001116064646464646416016016064646464160160Reconstructed block 0/1 bitmap Original

9、blockAverage=100High mean value = 160Low mean value = 64The flowchart of the proposed scheme embedding phase 13An example of the proposed scheme embedding phase 14An example of the proposed scheme embedding phase 15 Phase 1p Embed secret into the bitmapsAn example of the proposed scheme embedding ph

10、ase 16 Phase 2p Embed secret into (H, L)Final ResultAn example of the proposed scheme extraction phase 17 Phase 1p Extract secret from bitmapsAn example of the proposed scheme extraction phase 18 Phase 2p Extract secret from quantization pairsExperimental results19Test imagesExperimental resultsSche

11、meCriteriaLenaZeldaElainJetBoatGoldhillAverageAMBTCPSNR (dB)33.2336.7433.8333.2531.7632.8733.61Proposed schemePSNR (dB)28.9232.2529.4128.1429.17HC (bits)169,250168480172,479168,388170,103172,771170,245Chang et al.s scheme1PSNR (dB)30.7134.2631.2630.9931.0230.4931.45HC (bits)114,688114,688

12、114,688114,688114,688114,688114,688Chuang and Changs scheme2PSNR (dB)30.4533.9831.0730.5229.8430.5231.06HC (bits)13,05113,16913,24812,63711,98912,48612,763201 C.C. Chang, Y.J. Liu, and S.T. Nguyen, “Hiding Secret Information in Block Truncation Code Using Dynamic Programming Strategy,” In Proceeding

13、s of 6th International Graphic and Image Processing, vol. 9443, Beijing, China, 2014.2 J.C. Chuang and C.C. Chang, “Using a simple and fast image compression algorithm to hide secret information,” International Journal of Computers & Applications, vol. 28, no. 4, pp. 329-333, 2006.21ConclusionsnBased on the property of Hamming