(Solved):   Question 3 (17 marks) You must give a word count for any question with a maximum word limi ...

 

Question 3 (17 marks) You must give a word count for any question with a maximum word limit. You must show your mathematical working for full marks. This question tests your understanding of Block 2 Part 7 (Authentication and introduction to hashing) and Block 3 Part \( 3 . \) a. Authentication, hashing and encryption are useful tools for ensuring confidentiality and, integrity. Imagine "ABC Banking" is developing a fingerprint authentication system for its mobile phone banking application. Explain whether hashing or encryption or both would be helpful for the following: i. Transmission of the fingerprint data from the mobile phone to the bank's server. ii. Storage of the fingerprint data on the bank's database system. The maximum word count for Question \( 3(a) \) is 100 words. (8 marks) b. You have been asked to improve the security of a computer encryption system from 22-bit encryption to a 28-bit system. Answer the following questions. For each answer, you must show your working. i. How many possible keys are available in the 22-bit system? ii. How many possible keys are available in the 28-bit system? iii. How much more secure is the new 28-bit system than the 22-bit system? Note: You may find Activity \( 3.7 \) a useful reminder of Encryption keys. (4 marks) c. On Monday Bob and Alice exchange sensitive information using a specially generated session key. On Tuesday Alice receives a message in plaintext asking her to encrypt and send fresh sensitive information reusing the same key to avoid the overhead of exchanging a new one. Why should Alice be suspicious? What could have happened? (5 marks)