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1 /13. A New Steganographic Method for Data Hiding in Microsoft Word Documents by a Change Tracking Technique. Source: IEEE Transactions on Information Forensics and Security, Vol. 2, No. 1, pp. 24-30, March 2007 Authors: Tsung-Yung Liu and Wen-Hsiang Tsai
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1/13 A New Steganographic Method for Data Hiding in Microsoft Word Documents by a Change Tracking Technique Source:IEEE Transactions on Information Forensics and Security, Vol. 2, No. 1, pp. 24-30, March 2007 Authors: Tsung-Yung Liu and Wen-Hsiang Tsai Reporter: Hong-Hang Chang Date: Jun 6, 2010
2/13 Outline • Introduction • Related Work • Proposed Method • Experiment Result • Conclusion
3/13 Introduction In the degeneration stage, a subset of the text segment in a cover document D are degenerated… Message Degeneration and Revised In the degenerating degeneration stage, an a subset of the test text segment in a cover document D are degenelated degenerated… 3
4/13 Related Work • Huffman Tree “Databases” N0 N3 N4 D => 1 A => 3 T => 1 B => 1 S => 2 E => 1 N1 => 2 N2 => 2 N3 => 4 S N1 N2 A N4 => 5 D T B E Huffman Tree Constructing 4
5/13 Related Work (Cont.) N0 • Huffman Tree (Cont.) “Databases” N3 N4 0 1 D=> 010 A=> 11 T=> 011 B=> 100 S=> 00 E=> 101 S N1 N2 A 1 0 0 1 D T B E 0 1 0 1 Huffman Code (Databases) 5
6/13 Propose Method • Embedding D Microsoft Word Message S 6
7/13 Propose Method (Cont.) • Types of Generations 1. Spelling mistake and typos ex : paid/ payed 2. Confused word ex : complement/compliment 3. Others : Synonym, passivization, … 7
8/13 Propose Method (Cont.) • Embedding Degeneration set Rd for d = “travel” Secret message: 1100 Stegotext s= “ travel.” trip 8
9/13 Propose Method (Cont.) • Embedding That contains three entries : 1. “An illustrative example is shown,” (probability:4/6) (1) 2. “The illustrating example is shown,” (probability:1/6) (00) 3. “An illustrating example is shown,” (probability:1/6) (01) Degeneration set Rd for d = “An illustrative example is shown,” Secret message: 01 Stegotext s = “An illustrative example is shown,” illustrating 9
10/13 Propose Method (Cont.) • Exaction Stegotext s= “ travel.” trip Secret message: 1100 10
11/13 Propose Method (Cont.) • Exaction Stegotext s = “An illustrating illustrative example is shown,” d = “An illustrative example is shown” d’= “An illustrating example is shown” 1. “An illustrative example is shown,” (probability:4/6) (1) 2. “The illustrating example is shown,” (probability:1/6) (00) 3. “An illustrating example is shown,” (probability:1/6) (01) Secret message: 01 11
12/13 Experiment Result Table 1 EXPERIMENTAL RESULTS OF MESSAGE EMBEDDING CAPACITY 12
13/13 Conclusion • The proposed message embedding method • and extraction method providing the feasibility • of the proposed method. 13