利用網路聊天室傳送機密訊息 Chair Professor Chin-Chen Chang Feng Chia University National Chung Cheng University National Tsing Hua University
2 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
3 Synonym substitution Taichung is a 0 wonderful 1 decent 2 fine 3 great 4 nice little 0 city 1 town Secret message : (3) 5 (1) 2 Taichung is a great little town
4 Syntactic transformations Syntactic: the way that words and phrases are put together to form sentences in a language
5 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
6 Grafting He is detained in Japan. He, an American citizen, is detained in Japan.
7 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
8 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.
9 Translation 法文 : C ’ est la vie 英文 : That ’ s life. That is the life. It is the life. It ’ s life. Message AliceBob Stego object Cover object
10 Rule #RuleCodeProb. (1)S -> AB00.5 (2)S -> CB10.5 (3)A -> It is00.5 (4)A -> It’s10.5 (5)C -> That is00.5 (6)C -> That’s10.5 (7)B -> life00.5 (8)B -> the life (9)B -> a life PrefixRuleOutput 1(2)CB 0(5)That is B 10(8)That is the life Secret: 1010 Translation
11 Inter-word spacing scheme 1 This scheme exploits inter-word space of text to encode data. Thisisabook. Secret bits: {0 1 0} Thisisabook.
12 Inter-word spacing scheme 2 Weemploythecombinationoftherepeatedwords… Secret bits: { } Space change: ＋ － ＋ We employthecombinationof therepeated words… Keep spaces between groups unchanged.
13 Add-pattern Delete-pattern Information hiding in binary text Binary image
14 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
15 Information hiding in hypertext Extraction Secret message Embedding Cover hypertextStego hypertext Secret key
16 多媒體暨網路安全實驗室 ~ 歡迎加入 ~ Tags text file Secret: … <META capital letters small letters 0101 :the written states <body <p<p Information hiding in hypertext
17 Secret: … 多媒體暨網路安全實驗室 ~ 歡迎加入 ~ text file <META <body <p<p capital letters small letters 0101 :the written states Information hiding in hypertext
18 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.
19 Text steganography in chat SMS-Texting
20 Text steganography in chat Usual abbreviated words univ. university PC Personal Computer M.S. master of science UN United Nations Dr doctor
21 Text steganography in chat SMS list + abbreviated words list Check list full formabbreviated form0 full form, 1 abbreviated form
22 Text steganography in chat Embedding : “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
23 Emoticon-based steganography in chat Emoticon-based Text Steganography in Chat
24 Phase1: Classify the emoticons by their meaning Emoticon-based steganography in chat
25 Example: N = 16 hide log 2 N = 4 bits per emoticon sender uses second symbol receiver can extract 4 bits “0001” Emoticon-based steganography in chat
26 Phase2: emoticon || sentence : secret = 0 sentence || emoticon : secret = 1 I lost my bag secret = 0 secret = 1 Emoticon-based steganography in chat
27 Phase3: emoticon, sentence : secret = 0 emoticon, sentence : secret = 1, I lost my bag secret = 0 secret = 1 I lost my bag Emoticon-based steganography in chat
28 Zhihui wants to send secret bits “ ” to Alan3c ||1||1 Phase1 Phase2 Alan3c says: Just a kidding, you are the nicest guy I know in the world. Zhihui says: 00 Phase3 Alan3c says : You are a bad student! Zhihui says: Emoticon-based steganography in chat
29 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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