A Restricted Region-based Data-hiding Scheme Chair Professor Chin-Chen Chang Feng Chia University National Chung Cheng University National Tsing Hua University http://msn.iecs.fcu.edu.tw/~ccc

Outline Introduction Proposed scheme Experimental results Conclusions

Introduction (1/3) Traditional information hiding Secret Message: 110110110011 (Cover Image) (Stego Image)

Introduction (2/3) (cover pixels) 00110010 00111100 00111101 01001110 01011010 01011101 01100100 01011111 11001011 10101111 00011110 10010110 10110011 10111100 10011100 01011001 50 60 61 78 90 93 100 95 203 175 30 150 179 188 156 89 (cover pixels) (binary representation of cover pixels) Secret Message: 110110110011 00110011 00111101 00111110 01001111 01011000 01011111 01100100 11001011 10101111 00011110 10010110 10110011 10111100 10011100 01011001 (binary representation of stego pixels)

Introduction (3/3) Our proposed scheme Secret Message: 110110110011 Protected Region (Cover Image) (Stego Image)

Embedding Select protected regions Generate a location map Compress the location map with Huffman coding Embed the information

Select Protected Regions 50 60 61 78 90 93 100 95 203 175 30 150 179 188 156 89 Protected region

Generate a Location Map 1 changeable pixel 0  unchangeable pixel 50 60 61 78 90 93 100 95 203 175 30 150 179 188 156 89 1 Location map

Generate Tokens Get the tokens Type 1: 0…01 (ending with 1) Type 2: 11111111 (eight 1s) Type 3: single 1 Type 4: 00…00(ending with 0) 1 Token Frequency 11111111 1 2 000000

Condensed location map: 001101 Get the Huffman Code Get a condensed location map root 1 2 11111111 000000 Token Frequency codeword 11111111 1 00 2 000000 01 Location map: 1111111111000000 Condensed location map: 001101

Condensed Huffman code: Header: Ex. 1: 01100101 11100111 Cover pixel: Condensed Huffman code: 10 1 01100110 11100111 Stego pixel: 1: embedded 0: unembedded Header: 10

Header: Ex. 2: 01100101 11100111 Cover pixel: Huffman code: 10 01100110 11100110 Stego pixel: 1: embedded 0: unembedded Header: 11

Payload Header: 11 Huffman code: 001101 Secret information Header: 11 Huffman code: 001101 Secret information: 110110110011 Payload: 11• 001101 • 110110110011

Huffman code (Condensed location map): 001101 Ex 1: Huffman code (Condensed location map): 001101 The size of condensed location map = 6 (bits) 1+ = 4 Number of needed changeable pixels For header For condensed location map 1 2 3 4 1 Private Key: 11011 (Location map)

Huffman code (Condensed location map): 001101 Ex 2: Huffman code (Condensed location map): 001101 The size of condensed location map = 6 (bits) 1+ = 4 Number of needed changeable pixels For header For condensed location map 1 2 3 4 1 Private Key: 1111 (Location map)

(binary representation of cover pixels) 00110010 00111100 00111101 01001110 01011010 01011101 01100100 01011111 11001011 10101111 00011110 10010110 10110011 10111100 10011100 01011001 50 60 61 78 90 93 100 95 203 175 30 150 179 188 156 89 (cover pixels) (binary representation of cover pixels) Payload: 11• 001101 • 110110110011 Private key: 1111 00110011 00111100 00111111 01001101 01011011 01011101 01100110 01011111 11001000 10101111 00011110 10010110 10110011 10111100 10011100 01011001 51 60 63 77 91 93 102 95 203 175 30 150 179 188 156 89 (stego pixels) (binary representation of stego pixels)

Hiding capacity (bits) Experimental Results 512 X 512 = 262144 (bits) Changeable and unchangeable region Information Unchangeable region (white) (512 X 512) Huffman code (bits) 39972 39822 Two LSBs Private key (bits) 21601 19911 Hiding capacity (bits) 382306 377944 PSNR (dB) 45.0783 45.1281 Three LSBs 13324 13274 593445 582826 38.8685 38.8996

Conclusions Simple and efficient Hiding capacity is large Good stego image quality