Post on 18-Feb-2017
transcript
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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