The symbol K is magnified and shown in Figure 1 with a grid superimposed.
A. The symbol Kis magnified and shown in Figure 1 with a grid superimposed. Figure 1 The image in Figure 1 is to be encoded and encrypted using the following steps: a. Each of the five horizontal rows of the picture is encoded as a 5-bit binary number. White squares are encoded as Os and black squares as 1s. The top row is therefore encoded as 10011. b. Starting from the left, the first binary digit is multiplied by 16, the second by 8, the third by 4, the fourth by 2, and the fifth by 1. For the top row the result is: (1 * 16) + (0 * 8) + (0 * 4) + (1 * 2) + (1 x 1) = 16+ 0 + 0 + 2 + 1 = 19. c. The value representing each row is encrypted using modular addition with a modulus of 32 and a key of 25. d. The result is converted to a 5-bit binary number. Use steps a to d to work out the 5-bit binary number of each row. Show your working. (5 marks) B. This part of the question is based on the practical activities you did in Part 6. It relates to activities 6.86.14 where you registered an account and tested the Web server. i. This part of the question relates to Activity 6.8. For your answer to this part of the question include the screenshot that shows the welcome page after you successfully logged in to your account. The screenshot should show your name, PI number and email address. (2 marks) ii. This part of the question relates to Section 6.5 where you experiment with a simple Denial-of-service (DoS) attack. What is a DoS attack? In Activity 6.13, how can the DoS script attack the web server? What action(s) can be taken to mitigate the effect of the DoS attack? Explain your answer in about 120 words. (6 marks) A. The symbol Kis magnified and shown in Figure 1 with a grid superimposed. Figure 1 The image in Figure 1 is to be encoded and encrypted using the following steps: a. Each of the five horizontal rows of the picture is encoded as a 5-bit binary number. White squares are encoded as Os and black squares as 1s. The top row is therefore encoded as 10011. b. Starting from the left, the first binary digit is multiplied by 16, the second by 8, the third by 4, the fourth by 2, and the fifth by 1. For the top row the result is: (1 * 16) + (0 * 8) + (0 * 4) + (1 * 2) + (1 x 1) = 16+ 0 + 0 + 2 + 1 = 19. c. The value representing each row is encrypted using modular addition with a modulus of 32 and a key of 25. d. The result is converted to a 5-bit binary number. Use steps a to d to work out the 5-bit binary number of each row. Show your working. (5 marks) B. This part of the question is based on the practical activities you did in Part 6. It relates to activities 6.86.14 where you registered an account and tested the Web server. i. This part of the question relates to Activity 6.8. For your answer to this part of the question include the screenshot that shows the welcome page after you successfully logged in to your account. The screenshot should show your name, PI number and email address. (2 marks) ii. This part of the question relates to Section 6.5 where you experiment with a simple Denial-of-service (DoS) attack. What is a DoS attack? In Activity 6.13, how can the DoS script attack the web server? What action(s) can be taken to mitigate the effect of the DoS attack? Explain your answer in about 120 words. (6 marks)
