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Recent Developments in Text Steganography Chair Professor Chin- Chen Chang National Tsing Hua University National Chung Cheng University Feng Chia University http:// msn.iecs.fcu.edu.tw/~ccc http://

Recent developments in_text_steganography

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Page 1: Recent developments in_text_steganography

Recent Developments in Text Steganography

Chair Professor Chin-Chen ChangNational Tsing Hua University

National Chung Cheng University Feng Chia University

http://msn.iecs.fcu.edu.tw/~ccchttp://msn.iecs.fcu.edu.tw/

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Information hiding in general text Synonym substitution

Syntactic transformation

Translation

Semantic transformation

Information hiding in hypertext

Information hiding in binary text

Inter-word spacing schemes

Information hiding in chat text Text steganography in chat Emoticon-based steganography in chat

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Synonym substitution

Taichung is a 0 wonderful1 decent2 fine3 great4 nice

little0 city1 town

Secret message: (3)5(1)2

Taichung is a great little town

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Syntactic transformationsSyntactic: the way that words and phrases are put together to form sentences in a language

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Semantic transformation

• Grafting: adding or repeating information

• Pruning: removing repeated information

• Substitution: replacing information

Semantic :Describe things that deal with the meanings of words and sentences

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Grafting

He is detained in Japan.

He, an American citizen, is detained in Japan.

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Pruning

The Pentagon ordered two new spy planes to the region to start flying over Afghanistan.

Afghanistan has been under attack since October, and the Pentagon ordered two new spy planes to the region to start flying over there.

Afghanistan has been under attack since October

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Substitution

The Pentagon ordered two new spy planes to the region to start flying over Afghanistan.

Afghanistan Taliban ruled country

The Pentagon ordered two new spy planes to the region to start flying over the Taliban ruled country.

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Translation法文 : C’est la vie

英文 :That’s life.That is the life.It is the life.It’s life.

Message

Alice BobStego object

Cover object

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Rule # Rule Code Prob.

(1) S -> AB 0 0.5(2) S -> CB 1 0.5(3) A -> It is 0 0.5

(4) A -> It’s 1 0.5(5) C -> That is 0 0.5(6) C -> That’s 1 0.5(7) B -> life 0 0.5(8) B -> the life 10 0.25(9) B -> a life 11 0.25

Prefix Rule Output1 (2) CB0 (5) That is B

10 (8) That is the life

Secret: 1010

Translation

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Inter-word spacing scheme 1

• This scheme exploits inter-word space of text to encode data.

Thisisabook.

Secret bits: {0 1 0}

Thisisabook.

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Inter-word spacing scheme 2

Weemploythecombinationoftherepeatedwords…

Secret bits: { 1 0 1 1}Space change: + -      +We employthecombinationof therepeated words…

• Keep spaces between groups unchanged.

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Add-pattern Delete-pattern

Information hiding in binary text

Binary image

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Information hiding in binary text

• Embedding Secret bit 0 : A-pattern D-pattern D-pattern D-pattern Secret bit 1 : D-pattern A-pattern A-pattern A-pattern• Extracting D-pattern Secret bit 0 A-pattern Secret bit 1

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Information hiding in hypertext

ExtractionSecret message

Secret message

Embedding

Cover hypertext

Stego hypertext

Secret key

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<html><head><meta http-equiv="Content-Type" content="text/html; charset=big5"><title> 多媒體暨網路安全實驗室 </title></head><body bgcolor="#D27D1O"><p align="center"><img border="0" src="msn.jpg" width="338" height="345"></p><p align="center"><font face=" 標楷體 " color="#f4efe8" size="7">~ 歡迎加入~</font></p></body></html>

Tagstext file

Secret: 010110…

<META

capital letterssmall letters

01

:the written states

01

</title>1 2

3

456

<HTML>

</HTML>

0110

<body

<p

Information hiding in hypertext

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Secret: 010110…

<html><head><meta http-equiv="Content-Type" content="text/html; charset=big5"><title> 多媒體暨網路安全實驗室 </title></head><body bgcolor="#D27D1O"><p align="center"><img border="0" src="msn.jpg" width="338" height="345"></p><p align="center"><font face=" 標楷體 " color="#f4efe8" size="7">~ 歡迎加入~</font></p></body></html>

text file

<META1 2

3

456

<HTML>

</HTML>

<body

<p

capital letterssmall letters

01

:the written states

Information hiding in hypertext

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Text steganography in chat

Shirali-Shahreza, M.H., Shirali-Shahreza, M., “Text Steganography in Chat,” Proceedings of the Third IEEE/IFIP International Conference in Central Asia on Internet the Next Generation of Mobile, Wireless and Optical Communications Networks, Tashkent, Uzbekistan, Sep. 2007, pp. 1-5.

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Text steganography in chatSMS-Texting

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Text steganography in chat

Usual abbreviated words

• univ. university

• PC Personal Computer

• M.S. master of science

• UN United Nations

• Dr doctor

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Text steganography in chat

• SMS list + abbreviated words list Check list

• 0 full formfull form, 1 abbreviated formabbreviated form

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Text steganography in chatEmbedding : “Please call me when you feel upset.” secret “10” “Please CM when you feel upset.”Extracting : “Please CM when you feel upset.”

secret bits “10”

Check list

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Emoticon-based steganography in chat

Emoticon-based Text Steganography in Chat

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Phase1: Classify the emoticons by their meaning

Emoticon-based steganography in chat

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Example: N = 16 hide log2N = 4 bits per emoticon sender uses second symbol receiver can extract 4 bits “0001”

Emoticon-based steganography in chat

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Phase2: emoticon || sentence : secret = 0 sentence || emoticon : secret = 1

I lost my bagI lost my bag

secret = 0

secret = 1

Emoticon-based steganography in chat

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Phase3: emoticon , sentence : secret = 0 emoticon , sentence : secret = 1

, I lost my bag secret = 0

secret = 1I lost my bag

Emoticon-based steganography in chat

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Zhihui wants to send secret bits “11100000111” to Alan3c.

1110

001||1||1Phase1Phase2

Alan3c says:Just a kidding, you are the nicest guy I know in the world.Zhihui says:

0 0Phase3

Alan3c says : You are a bad student!Zhihui says:

Emoticon-based steganography in chat

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Future Research Direction

• Chinese text steganography

壞的毛病 壞毛病 山東的蘋果 山東蘋果 我的媽媽 我媽媽 主要的問題 主要問題 另外的一件事 另外一件事 其他的問題 其他問題 北京的大學 北京大學

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