本次新加坡代写是密码学相关的一个Assignment
Aim: This assignment is designed to help you improve your critical thinking and problem solving skills, as well as your information literacy skills (i.e. the ability to select and organise information and to communicate it effectively and ethically).
Requirements, Method of Submission, and Marking Criteria:
Answer all of the following questions in a single document. Each question should begin on a new page.
Include your name on the first page.
Include list of references for each question with proper in-text citations.
For each of the first two (2) questions, write a report of approximately 750 words in the structure of a scientific paper (e.g., articles and/or conference papers).
In your answer to question 3 (i.e., cryptanalysis), show all your work. Note that using the Internet for deciphering the cryptogram and/or learning the key from any other sources is an instance of plagiarism. You have to show (step-by-step) how did you achieve the plaintext and key.
For marking criteria, see the included rubrics.
Upload your solution to the Assignment Box, located in the subject’s site.
1. Answer a) OR b)
a)
Using the web, find out who Kevin Mitnick was.
What did he do?
Who caught him?
Write a short summary of his activities and why he is famous. b)
What went wrong at Sony Entertainment? Review the Fortune Magazine article Hack of the Century and other resources and summarize what went wrong and why.
2. One-Time Pad (OTP) – An unbreakable cryptographic system
Use the Internet to search OTPs; who was behind the initial idea, when they were first used, in what application they were found, how they are used today, etc. Then visit an online OTP creation site (such as www.braingle.com/brainteasers/codes/onetimepad.php) and practice creating your own ciphertext with OTP. Exchange your OTPs with other students to see how you might try to break them. Would it be practical to use OTPs? Why or why not? Can you find any references about its use in practical situation? Write a short summary on your findings.
3. Cryptanalysis of Substitution Ciphers
In this question you learn a classical monoalphabetic (substitution) cryptographic system, and are required to cryptanalysis a given cryptogram.
In substitution ciphers, a permutation of the alphabet is chosen as the cryptogram of original alphabet. That is, every letter of the plaintext substitutes by corresponding letter in the permuted alphabet. For example,
a b c d e f g h i j k l m n o p q r s t u v w x y z c o d k s z r g e l u y a f m v p h i n w t b j q x
Figure 1: A possible permutation of English alphabet
is one of such permutation, in which letters a,b,c,···,y,z from the plaintext are substituted by corresponding letters c,o,d,···,q,x respectively. Since remembering permutation is not easy, one may employ a keyword and use a table to generate the permuted alphabet. Let CRYPTOGRAPHY be the keyword. The permuted alphabet can be obtained as follows.
Choose a 6 × 5 table/matrix, i.e., a table with 6 rows and 5 columns.
Write down the secret keyword in cells (1,1),(1,2),···, one letter in each cell, but skip repeated letters. Figure 2 shows how ‘CRYPTOGRAPHY’ (as a keyword) written down in the table.
Write alphabet letters (in order) from the first available cell after keyword, but skip all letters that are already written in the table. You will come out with Table 3.
The permuted alphabet, which will be used to generate the cryptogram, can be obtained by simply reading the content of Table 3 in columns order (Which gives you the cryptogram alphabeth of Figure 1).