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

ImageIndex table

Vector Quantization Encoder

wh

VQ Compression

ImageIndex table

Vector Quantization Decoder

wh

VQ Compression

PSNR = 29.62 dB Accuracy rate 99.95%

Watermarking

CW0

CW1

CW2

CW3

CW4

CW9

CW10

CW11

CW12

CW6

CW7

CW8

CW14

CW15

CW13

CW5

CODEBOOK

Finds the nearest pairs

CW0

CW1

CW2

CW3

CW4

CW9

CW10

CW11

CW12

CW6

CW7

CW8

CW14

CW15

CW13

CW5

Find d(CW0, CW8) > TH

d(CW13, CW14) > TH

Unused

CW0, CW8, CW1

3, CW1

4

hide 1

hide 0

CW1

CW11

,CW2

,CW3

CW4, CW5

CW6, CW7

CW15, CW10

CW12, CW9

w

h

Original Image Index Table

Index TableUnused

CW0, CW8,

CW13, CW14

Encode

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

Index Table

11

00 0 1

0 11 1

10

0

CW1, CW2,

CW4, CW5

CW6, CW7

CW11, CW3

CW15, CW10

CW12, CW9

hide 1 hide 0

1 0

Water mark

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

Index Table

11

00 0 1

0 11 1

10

0

CW1, CW2,

CW4, CW5

CW6, CW7

CW11, CW3

CW15, CW10

CW12, CW9

hide 1 hide 0

1 0

Water mark

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

Index Table

11

00 0 1

0 11 1

10

0

1 0

Water mark

Search-Order Coding (SOC)

An example for indices of VQ

Search-Order Coding (SOC)

321

04

5

6 7 8 9 10

11

Searched point Non-searched point

31 207 207

211

31 207 8 20731 211 8 735 31 8 7

The compressing steps

Search-Order Coding (SOC)

P1 = 1 00011111

Indicator

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

Information hiding on the SOC codes

Main idea:Ex. receiver receives the compression codes : 010101101110110110011000011

SOC SOC SOCOIVOIV(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”.

Information hiding on the SOC codes

Method:ex. A 3*3 index table:

1 2 3

1 18 21 31

2 30 30 31

3 29 30 32

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

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”

+ OIV11(SOC)

Information hiding on the SOC codes

Information hiding on the SOC codes

Ex.

compression codes are still OIV: 100010010

translate SOC into OIV : 000 => 100011110

translate OIV into SOC : 100100000 => 01100100000

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.

Information hiding on the SOC codes

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

the current index

U

L

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

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)

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’

‘10’ ‘00’||(128) …

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’

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

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

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

Experiment results

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