Choose any 3 question from below and write your answer in a form of research report. Your answer should be maximum one and half to two page with single space and font size of 11 and margin of 1". Your document should have references.:
Q1. Explain why the product of two relatively simple ciphers, such as a substitution and a transposition, can achieve a high degree of security.
Q2. Humans are said to be the weakest link in any security system. Give an example of human failure that could lead to compromise of encrypted data.
Q3. List three kinds of data whose lifetime (amount of time for which confidentiality protection is needed) is approximately one day. List three whose lifetime is closer to one year. List three whose lifetime is closer to one century.
Q4. Why do cryptologists recommend changing the encryption key from time to time? How frequently should a cryptographic key be changed?
Q5. How would you quickly test a piece of ciphertext to suggest whether it was likely the result of a simple substitution?
Q6. Does a substitution need to be a permutation of the plaintext symbols? Why or why not?
Q7. How would you quickly test a piece of ciphertext to suggest whether it was likely the result of a transposition?