T215B: Communication and information technologies ______________________________________________________________________________ Tutor-Marked Assignment _____________________________________________________________________________ Cut-off date: December 10, 2013 _____________________________________________________________________________ Total Marks: 100 Contents Part 1: Cryptography (50 Marks) 2 Part 2: Securing a report (50 Marks) 3 2.A. Privacy, surveillance and security threats 3 2.B. Caesar Cipher 4 2.C. Caesar Cipher with Diagraph Coding 4 2.D. Vigenère Cipher 4 2.E. Recommendations 4 Plagiarism Warning: As per AOU rules and regulations, all students are required to submit their own TMA work and avoid plagiarism. The AOU has implemented sophisticated techniques for plagiarism detection. You must provide all references in case you use and quote another persons work in your TMA. You will be penalized for any act of plagiarism as per the AOUs rules and regulations. Declaration of No Plagiarism by Student (to be signed and submitted by student with TMA work): I hereby declare that this submitted TMA work is a result of my own efforts and I have not plagiarized any other persons work. I have provided all references of information that I have used and quoted in my TMA work. Name of Student:……………………………….. Signature:…………………………………………... Date:…………………………………………………… Part 1: Cryptography (50 Marks) As an AOU student, suppose that you were attending a T215B discussion session during which many questions about data encryption in general were raised as well as other questions about a well-known cryptographic algorithm called RSA in particular. Those can be summarized as follows: • Encryption: (6 Marks) What is encryption? What is it used for? What are its advantages and disadvantages? • Symmetric key cryptography: (6 Marks) What is symmetric key cryptography? What are its applications? What are its advantages and disadvantages? • Asymmetric and public key cryptography: (6 Marks) What is asymmetric key cryptography and why it is usually called public key cryptography? What are its applications? What are its advantages and disadvantages? • Modular arithmetic: (8 Marks) What is Modular arithmetic in general? What are Modular addition, multiplication and exponentiation? Examples? • Factorizing large prime numbers: (6 Marks) What is a prime number? How large prime numbers can be useful to cryptography? • RSA keys generation technique: (7 Marks) What is RSA algorithm? How to create the RSA public and private keys? Since the students were highly interested and motivated to understand what encryption and RSA algorithm are about, the mentor of this discussion session asked you as an active participant to elaborate reliable answers to these raised questions by editing a medium length report (1000-1200 words). He also offered you the opportunity to present this report to all your classmates during the next discussion session. In this question of the TMA, you are supposed to edit the requested report taking into consideration the following points: Your report should be between 1000 and 1200 words in length. Under-length and over-length reports will be penalized. (2 Marks) Your report must provide reliable answers for all the above questions. (Check the marks awarded for each concern) You might need to form some idea of how many words you need to give to each concern. (Check the marks awarded for each concern) Your report should include titles, subtitles and at least two figures and/or tables. Do not forget to include captions and to use cross-referencing. (3 Marks) Ensure that your report meets the objectives, has an appropriate structure and style, and that its technical level is appropriate for the audience, purpose and medium. For more details, you can refer to the T215 textbooks (Block 1 – Part 7; Block 2 – Part 7; Block 3; Block 4 – Part 8). (3 Marks) Your report should be based on reliable resources (i.e. journal articles, technical reports, conference papers, international textbooks) and you should provide a reference list at the end of your report. The references should be in a standard form. (3 Marks) You are advised to remind yourself of the issues concerning plagiarism. Part 2: Securing a report (50 Marks) The Arab Open University – AOU – is a multinational university with several branches around the Arab World. Recently, it has been earning itself a reputation for its success in credibility and high educational issues. Suppose that you are working as a financial expert in one of the AOU’s Branches and that you were asked to edit a highly confidential report about the financial activities at your Branch. After two weeks of hard work, you finalized the report and now it is ready to be delivered. However, as per an urgent request from the AOU headquarters, your Branch Director was invited to attend an urgent meeting outside the country to discuss your Branch’s financial activities and he hence asked you to send him by email a soft-copy of the report you prepared taking into consideration the sensibility of the information it contains. In this question of your TMA, you are supposed to investigate three different encryption techniques and to deduce which one of them provides for your report the highest level of confidentiality. 2.A. Privacy, surveillance and security threats Based on what you learned in T215B about “Privacy and Surveillance”, discuss two different kinds of threats that might confront your confidential report when it is sent by email to your Branch director. (Respect a maximum word count of 200 words). (6 Marks) In all the following questions and for simplicity reasons, suppose that your report contains the following sentence: “High Profit”. 2.B. Caesar Cipher a) In no more than 150 words explain the Caesar encryption technique. (4 Marks) b) Use Caesar algorithm to encrypt the content of your report with a key K=14. (4 Marks) c) Does the Caesar cipher ensure a high level of security? What are its drawbacks? Explain. (2 Marks) d) What is the decryption key your director should use to decrypt the encrypted report? (2 Marks) 2.C. Caesar Cipher with Diagraph Coding a) In no more than 150 words explain the main idea of Diagraph coding. Does its implementation in a Caesar Cipher algorithm increase the security level of the ciphertext? Why/Why not? (5 Marks) b) Use Caesar Cipher with Diagraph Coding to encrypt the content of your report with a key K=321. (8 Marks) 2.D. Vigenère Cipher a) In no more than 150 words explain the main idea of the Vigenère Cipher. Does it ensure a high level of security? What can make it an unbreakable cipher? Illustrate. (6 Marks) b) Use the keyword “zratxhuekf” to encrypt the content of your report using the Vigenère Cipher. (5 Marks) c) What is the keyword that might be used to decrypt the ciphertext? (5 Marks) 2.E. Recommendations Which of the previously studied ciphers would you recommend using to encrypt your report before sending it to your Director? Give strong arguments for you recommendation. (3 Marks) Notes for Question 2: In questions 2.B.b, 2.C.b and 2.D.b, you are requested to illustrate, step by step, how you have applied each encryption technique. You can use external reliable resource(s) to elaborate your answers but ensure that you provide its (their) reference(s) at the end of your answer. The reference(s) should be in a standard form. You are advised to remind yourself of the issues concerning plagiarism. *************************** End of TMA
Posted on: Mon, 02 Dec 2013 19:13:05 +0000
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