Homework answers / question archive / BICT Assessment IT6010 Maths for Computing IT6010– Maths for Computing – Assignment Submissions Instructions The students should submit the work as a group assigned by the tutor

BICT Assessment IT6010 Maths for Computing IT6010– Maths for Computing – Assignment Submissions Instructions The students should submit the work as a group assigned by the tutor

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BICT Assessment IT6010 Maths for Computing

IT6010– Maths for Computing – Assignment

Submissions Instructions

• The students should submit the work as a group assigned by the tutor.
• Submit your work through the practical assignment scenario link on the course Moodle page.
• The submission of the word report must be in document format(doc.). Any submission with RAR format is not allowed and the group will get zero mark for that.
• In the word file, for each question that requires Octave programme, add a screen shot of the code, the output obtained from running the programme, then your comments and/ or explanation.
• Octave code files need to be named by the student_ ID and question number (e.g. for the student ID 20201111, the naming is 20201111­­_Q1, 20201111_Q2, etc.) then submitted uncompressed.

Marking:

The marking will be done according to the marking scheme.

The Questions:

                                                                                                                                                                                                                         

Q1) Design a Knapsack public key cryptosystem, using this system, encrypt the plaintext “ABC”. Show the details of the design process (give the selected values with explanation why selected them) and encryption process. Include in your answer Octave programmes used. Use the ASCII code to represent the plaintext characters as numbers. Then, show how to decrypt the obtained cipher values to get back the plaintext character.                      (LOs 2,4) [6 Marks]                                                                       

                                                                            

                                                                              

Q2)   Answer each of the following:                                                    

1. What are the weaknesses in Monoalphabetic Cipher [Mixed Alphabet] that can be exploited to break that type of ciphers?
2. Describe briefly three applications/systems that can be used to add digital signature to a document.
3. Compare between Stream Cipher System and Block Cipher Systems. Give one example for each system.    

                                                                                                        (LO 4) [3 Marks]                                                                                                                                                                                                                                                      

Q3) Affine Cipher is an example of a Monoalphabetic substitution cipher. The encryption process is substantially mathematical done by using the following formula:

          C = (P ∗ ?1 + ?2) mod 26.

       Where k1, k2 are two integers representing the key (selected randomly), C is the ciphertext value, and P is the plaintext value. Where C and P integers with values between 0 and 25.

1. Write an Octave programme to implement this system, run your programme using the       Plaintext: “the quick brown fox jumped over the lazy dog”. Show the obtained ciphertext with the selected values of the keys k1 & k2.
2.  Given that the plaintext “s” encrypts to ciphertext “W” and plaintext “x” encrypts to ciphertext “Z” when encrypted with Affine Cipher. Determine, mathematically, the values for the two keys K1 and K2.                                                              (LOs 2,4) [5 Marks] 

Q4) Describe in detail the Playfair cipher the show how to encrypt the message

      “HELLO WORLD”

     With the “playfair cipher” key word to be used in the encryption process and show the obtained ciphertext.                                                                                   (LO4) [3 Marks]

Q5) Given the following cipher text which ahs been cipher with Mixed Alphabet Monoalphabetic Cipher:

UZQSOVUOHXMOPVGPOZPEVSGZWSZOPFPESXUDBMET SXAIZVUEPHZHMDZSHZOWSFPAPPDTSVPQUZWYMXUZU HSXEPYEPOPDZSZUFPOMBZWPFUPZHMDJUDTMOHMQ

By using statistical method and by exploiting the weaknesses in this cipher, you can guess the two plain text letters that corresponds to two letters in the above ciphertext. Justify your answer in detail.                                                                                           (LO1)