Session – 16 Session Name: Technical Steganography Author Name: Dr. Qaim Mehdi Rizvi Department: Computer Science & Engineering Subject/Course: IT in Forensic Science
Session Objectives At the end of this session, the learner will be able to: Understand the Role of Technical Steganography in Information Security Analyze the types of Technical Steganography Apply some home-made applications for Information Hiding Outline the pros & cons of different Steganographic approaches
Teaching Learning Material Chalk & Duster Projector, Laptop & MS Power Point Lemon Juice, Plain Paper, Stick & A lamp/ OHP
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Session Plan Time (in min)
Content
Faculty Approach
Typical Student Activity
Analogy
Facilitates Explain
Listens Participates Discusses
10
Need of Technical Steganography
Group Discussion
Facilitates Guides
Discusses Analysis Questions Answers
15
Types of Technical Steganography
Demonstration through PPT
Facilitates Guides
Listens Participates
The Applications of Technical Steganography
Visual Aid
Facilitates Guides Monitors Debriefs
Participates Observes Comprehends Listens
Pros & Cons of Technical Steganography
Chalk & Talk
Facilitates Verifies Tabulates
Listens Identifies Discusses
Conclusion
MCQs
Conduct
Participates Answers
15
10
05
05
Introduction to Technical Steganography
Learning Aid and Methodology
Learning Outcomes (Blooms + Gardeners)
Listens Participates
Analyzing Intrapersonal Interpersonal Logical Understanding Intrapersonal Visual Applying Intrapersonal Interpersonal Verbal-Linguistic Analyzing Intrapersonal Linguistic Understanding Interpersonal Verbal- Linguistic
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Session Inputs Introduction to Technical Steganography Introduce the historical importance of information hiding and the possible ways by which we can hide our valuable data. The historical example can be used to increase student’s interest in Technical Steganography.
Suggested Activity: ANALOGIES We can narrate some analogies to illustrate the importance of steganography in the secure information sharing. In the historic edge, the steganography was even in use. Some sample analogy are as follows: v The first recorded uses of steganography can be traced back to 440 BC when Herodotus mentions two examples of steganography in his Histories. Demaratus sent a warning about a forthcoming attack to Greece by writing it directly on the wooden backing of a wax tablet before applying its beeswax surface. Wax tablets were in common use then as reusable writing surfaces, sometimes used for shorthand. v Another ancient example is that of Histiaeus, who shaved the head of his most trusted slave and tattooed a message on it. After his hair had grown the message was hidden. The purpose was to instigate a revolt against the Persians.
Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity. The word steganography is of Greek origin and means "concealed writing.
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Need of Technical Steganography To apply the technical steganography and use them effectively, it is very important to first understand the implications and advantages of each. The instructor can conduct a group discussion at this point.
Suggested Activity: GROUP DISCUSSION Students should aware about the need of steganography. A group discussion can enhance their logical thought about the different ways to hide information from others. After that a conclusion should be come out for clarification about their ideas. Five minutes can be given for the discussion. Each group can be then be asked to summarize their analysis and present the same to the class. The key points can be noted on the board and finally, the facilitator can consolidate and enhance the perspectives.
Types of Technical Steganography The technical steganography is purely a practical based approach for information hiding. It is based on external support for hide and/or temporally changes the data for security purpose.
Suggested Activity: DEMONSTRATION THROUGH PPT There are various approaches for technical steganography. Some of those are used since approximately 500 BC and some are most recent technique to implement technical steganography. Given images shows the way of technical steganography: 1. In an age before paper was available, when your only method of making a page to write upon was to either pound slices of papyrus together or to flay a hide and process it for several weeks, there existed a common alternative which was
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reusable, inexpensive, and conveniently portable.
Historical example is Demeratus, a Greek at the Persian court, warned Sparta of an imminent invasion by Xerxes, King of Persia: he removed the wax from a writing tablet, wrote his message on the wood underneath and then covered the message with wax. The tablet looked exactly like a blank one (it almost fooled the recipient as well as the customs men). 2. A very smart technique proposed by hiding text by changing the heights of letter strokes or by making very small holes above or below letters in a cover-‐text. This latter technique was still in use during the 17th century, but was improved by Wilkins (1614–1672) who used invisible ink to print very small dots instead of making holes and was reused again by German spies during both World Wars.
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3. Invisible inks have been used extensively. They were originally made of available organic substances (such as milk or urine) or "salt dissolved in water" and developed with heat; progress in chemistry helped to create more sophisticated combinations of ink and developer by the first World War, but the technology fell into disuse with the invention of "universal developers" which could determine which parts of a piece of paper had been wetted from the effects on the surfaces of the fibers.
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Pros & Cons of Technical Steganography Students should able to understand the requirements and the limitations of every algorithm. By critical analysis of an algorithm, it is more feasible to develop interest in next proposed approach for steganography.
Suggested Activity: Brain Storming We can pick students one by one and ask him to tell one-‐strength and one weakness of technological steganography and discuss with other students. Instructors may also take their individual opinion with will be able to produce some innovative opinions.
Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity. The word steganography is of Greek origin and means "concealed writing.
Pros & Cons of Technical Steganography Students should able to understand the requirements and the limitations of every algorithm. By critical analysis of an algorithm, it is more feasible to develop interest in next proposed approach for steganography.
Suggested Activity: Brain Storming We can pick students one by one and ask him to tell one-‐strength and one weakness of technological steganography and discuss with other students. Instructors may also take their individual opinion with will be able to produce some innovative opinions.
Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity. The word steganography is of Greek origin and means "concealed writing.
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Conclusion The best way to conclude the overall session is to check the knowledge status of students and re-‐brush the knowledge in an interesting way.
Suggested Activity: Multiple Choice Questions We can give the following multiple choice questions to the learners to help them review or revise the concepts and terms that were discussed during this session. We can form the learners into groups of eight each. Hard copies of the following question sheet can be circulated among all the groups. The questions can be distributed into the set of 10 different questions. The solution can be discussed and the fully solved puzzle can be displayed. 1. ____________ is the science and art of transforming messages to make them secure and immune to attacks. a. Cryptography b. Cryptoanalysis c. Either a or b d. Neither a nor b 2. The ________is the original message before transformation. a. Cipher Text b. Plain Text c. Secret Text d. None of above 3. The ________ is the message after transformation. a. Cipher Text b. Plain Text c. Secret Text d. None of above Technical Steganography Dr Qaim Mehdi Rizvi
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4. A/An ____________ algorithm transforms plain text into cipher text. a. Encryption b. Decryption c. Either a or b d. Neither a nor b 5. A/An ____________ algorithm transforms chipher text into plain text. a. Encryption b. Decryption c. Either a or b d. Neither a nor b 6. A combination of an encryption algorithm and a decryption algorithm is called a ________. a. Cipher b. Secret c. key d. None of above 7. The _______ is a number or a set of numbers on which the cipher operates. a. Cipher b. Secret c. key d. None of above 8. In a/an _____________________ cipher, the same key is used by both the sender and the receiver. a. Symmetric Key b. Asymmetric Key c. Either a or b d. Neither a nor b 9. In a/an ______________, the key is called the secret key. a. Symmetric Key b. Asymmetric Key c. Either a or b d. Neither a nor b Page 10 Ver : 1.02 Steganography Dr Qaim Mehdi Rizvi
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10. In a/an ____________ cipher, a pair of keys is used. a. Symmetric Key b. Asymmetric Key c. Either a or b d. Neither a nor b
11. In an asymmetric-‐key cipher, the sender uses the__________ key. a. Private b. Public c. Either a or b d. Neither a nor b 12. In an asymmetric-‐key cipher, the receiver uses the ______ key. a. Private b. Public c. Either a or b d. Neither a nor b 13. A ________ cipher replaces one character with another character. a. Substitution b. Transposition c. Either a or b d. Neither a nor b 14. The _____________ cipher is the simplest monoalphabetic cipher. It uses modular arithmetic with a modulus of 26. a. Transposition b. Additive c. Shift d. None of above 15. The Caesar cipher is a __________cipher that has a key of 3. a. Transposition b. Additive c. Shift d. None of above
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16. The ________ cipher reorders the plaintext characters to create a cipher text. a. Substitution b. Transposition c. Either a or b d. Neither a nor b 17. A/ An _________ is a keyless substitution cipher with N inputs and M outputs that uses a formula to define the relationship between the input stream and the output stream. a. S-‐box b. P-‐box c. T-‐box d. None of above
18. A/ An _____________is a keyless transposition cipher with N inputs and M outputs that uses a table to define the relationship between the input stream and the output stream. a. S-‐box b. P-‐box c. T-‐box d. None of above 19. A modern cipher is usually a complex _____________cipher made of a combination of different simple ciphers. a. Round b. Circle c. Square d. None of above 20. The DES is a/ an ____________ method adopted by the U.S. government. a. Symmetric Key b. Asymmetric Key c. Either a or b d. Neither a nor b
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21. DES has an initial and final permutation block and _________ rounds? a. 14 b. 15 c. 16
d. None of above 22. The DES function has _______ components. a. 2 b. 3 c. 4
d. 5
23. DES uses a key generator to generate sixteen _____________ round keys. a. 32-‐bit b. 48-‐bit c. 54-‐bit
d. 42-‐bit
24. The _______________ DES was designed to increase the size of the DES key. a. Double b. Triple
c. Quadruple
d. None of above 25. _______ is a round cipher based on the Rijndael algorithm that uses a 128-‐bit block. a. AEE b. AED c. AER
d. AES
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26. AES has _________________ different configurations. a. 2 b. 3 c. 4
d. 5 27. ECB and CBC are _____________ ciphers. a. Block b. Stream c. Field
d. None of above 28. One commonly used public-‐key cryptography method is the __________ algorithm. a. RSS b. RAS c. RSA
d. RAA 29. The ___________ method provides a one-‐time session key for two parties.
a. Diffie-‐Hellman b. RSA c. DES d. AES 30. The _____________ attack can endanger the security of the Diffie-‐Hellman method if two parties are not authenticated to each other. a. Man-‐in-‐the-‐Middle b. Ciphertext c. Plaintext d. None of above
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The solution of each question set will be announced in the class room for self-‐ assessment of students.
Assignment 1. Write down the role of IT in the security of any organizational system. 2. Define the concept of biometrics. Also illustrate what are the issues in the implementation of biometric systems with the help of modern computer system? 3. Define FAR (False Acceptance Rate) and FRR (False Rejection Rate) in context to biometric system. 4. Explain the process of biometric matching system with the help of block diagram. 5. “A biometric match proves that I am who I say I am”. Is it right or wrong? Justify your answer with the help of example. 6. Differentiate between the two processes: Verification and Identification. 7. Define the role of watch list in the process of any kind of recognition system. 8. Write down the process of biometric enrollment with the help of any real life example.
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References 1. Katzendbisser, Petitcolas, “Information Hiding Techniques for Steganography and Digital Watermarking", Artech House. 2. Peter Wayner, "Disappearing Cryptography: Information Hiding, Steganography and Watermarking 2/e", Elsevier. 3. Julian Ashbourn, "Guide to Biometrics for Large-‐Scale Systems", Springer. 4. John Vecca, “Computer Forensics: Crime scene Investigation”, Firewall Media. 5. Christopher L.T. Brown, “Computer Evidence: Collection and Preservation”, Firewall Media. 6. John Lach, WIlliam H. Mangione-‐Smith, and Miodrag Potkonjak. Fingerprinting digital circuits on programmable hardware. Information Hiding Workshop, Lecture Notes of Computer Science (1525), New York, Heidelberg, 1998. Springer-‐Verlag. 7. Walter Bender, D. Gruhl, N.Morimoto, and A. Lu. Techniques for data hiding. IBM Systems Journal, 35(3):313, 1996.
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