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A Secret Information Hiding Scheme Based on Switching Tree Coding. Speaker: Chin-Chen Chang. Outline. VQ image compression Watermarking Search order coding (SOC) Switching tree coding (STC). VQ Image Compression. VQ Compression. w. h. Image. Index table. Vector Quantization Encoder.

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A Secret Information Hiding Scheme Based on Switching Tree Coding

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A Secret Information Hiding Scheme Based on Switching Tree Coding

Speaker: Chin-Chen Chang


Outline

  • VQ image compression

  • Watermarking

  • Search order coding (SOC)

  • Switching tree coding (STC)


VQ Image Compression


VQ Compression

w

h

Image

Index table

Vector Quantization Encoder


VQ Compression

w

h

Image

Index table

Vector Quantization Decoder


Watermarking

Accuracy rate 99.95%

PSNR = 29.62 dB


Finds the nearest pairs


CW1

,CW2

CW4, CW5

CW6, CW7

CW0, CW8, CW13, CW14

hide 1

,CW3

CW11

CW15, CW10

CW12, CW9

Unused

hide 0

  • Find d(CW0, CW8) > TH

    d(CW13, CW14) > TH


CW0, CW8, CW13, CW14

Unused

Encode

Index Table

Index Table


1

0

0

1

  • Water mark: 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0

1

0

0

1

1

1

0

1

1

0

0

Index Table

Water mark

CW1, CW2,

CW4, CW5

CW6, CW7

CW11, CW3

CW15, CW10

CW12, CW9

hide 1

hide 0


1

0

0

1

  • Water mark: 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0

1

0

0

1

1

1

0

1

1

0

0

Index Table

Water mark

CW1, CW2,

CW4, CW5

CW6, CW7

CW11, CW3

CW15, CW10

CW12, CW9

hide 1

hide 0


1

0

0

1

  • Water mark: 1 0 1 0 1 0 0 1 0 1 1 1 1 0 0

1

0

0

1

1

1

0

1

1

0

0

Index Table

Water mark


Search-Order Coding (SOC)


An example for indices of VQ


Search-Order Coding (SOC)

Searched point

Non-searched point


Search-Order Coding (SOC)

Indicator

The compressing steps

P1 = 1 00011111

P2 = 1 11001111

P3 = 0 00

P6 = 0 10

Compression codes = 100011111 111001111 000 …


Information hiding on the SOC codes

  • The proposed scheme:

    - Information hiding:

    to embed secret data into host image

    - Steganography :

    to embed secret data into host image and the interceptors will not notice the existence of secret data

    - Based on SOC


OIV

(original index value)

Information hiding on the SOC codes

  • Main idea:

    Ex. receiver receives the compression codes :

    010101101110110110011000011

SOC

OIV

SOC

SOC

It means that the embedded secret data is “01100” if SOC is represented to hide “0” and OIV is represented to hide “1”.


Information hiding on the SOC codes

  • Method:

    ex. A 3*3 index table:

If the secret data is “111110100”, then the hiding position of each bit will be in the raster scan order.


hide “0”

SOC ====> there is nothing that needs to change for its

compression codes

hide “1”

SOC ====> translate SOC into OIV

(give up SOC coding and keep the OIV)

hide “1”

OIV ====> there is nothing that needs to change

hide “0”

OIV ====> translate OIV into SOC

ex.

11

(SOC)

Information hiding on the SOC codes

Defined: “0”  embedded into SOC and

“1”  embedded into OIV.

  • Embedding phase:

+ OIV


compression codes are still OIV: 100010010

translate SOC into OIV : 000 => 100011110

translate OIV into SOC : 100100000 => 01100100000

Information hiding on the SOC codes

  • Ex.


Information hiding on the SOC codes

  • Cost table (bits):


Information hiding on the SOC codes

  • 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.


Experimental results


Experimental results


Experimental results


Experimental results


Switching tree coding (STC)


Switching-tree coding (STC)

  • Sheu proposed the STC algorithm in 1999

  • Re-encode the index table

U

L

the current index


Switching-tree coding (STC)

  • If P = 7, then P = U

    • P’ = ‘11’

  • If P = 10, then P = L

    • P’ = ‘10’


  • If P = 14, then P = A in index (3)

    • P’ = ‘01’ || index (3) = ‘0100011’

  • If P = 17, then

    • P’ = ‘01’ || (17) = ‘0010001’


Information Hiding on the STC codes (IHSTC)


Information Hiding on the STC codes (IHSTC)

  • Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 …

Index table


P’ = ‘00’||(10)

‘00’||(25)

‘00’||(21) …

‘00’||(17)

Information Hiding on the STC codes (IHSTC)

  • Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 …


‘10’

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’

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’‘00’||(128) …


‘11’

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’‘00’||(128) …

‘10’


Three binary connection tree


Three binary connection tree

  • If U-length > L-length then

    • Tree B

  • If U-length < L-length then

    • Tree C

  • Otherwise Tree A

Tree B

Tree C


Experiment results

Image size = 512*512, n = 3 and |H| = 1024


Experiment results

Image size = 512*512, n = 3 and |H| = 2048

Image size = 512*512, n = 3 and |H| = NSTC


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


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