Part I: Choose the best one. Please provide reason of your choice in a few sentences or reasons not choosing the other choices. Reason must be in your own words. Use guidelines for reference as given in the instructions.

1. Which of the following four choices is not a part of a suggested information security plan?

a. protection of the information itself at the core

b. hardening of our resources (systems and networks)

c. authentication of those accessing the information

d. distributing predetermined strong passwords

2. Risk assessments only need to be conducted one time in the life of a security plan.  True/False    justify your answer

3. Which is not a weakness of a shift cipher?

a.  Natural language letter frequency makes them easy to decode.

b. The number of letters in the alphabet makes them easy to decode.

c.  Once the shift is determined the message is decoded almost instantly.

d.  Once you have the code book you can decode the message

4. What is the second layer of the Information Security Model?

a. web services layer

b. operating systems hardening layer

c. network architecture layer

d. cryptographic services layer

5. Historically, the primary reason for advances in cryptography has been _____________.

a. protecting business assets

b. wars

c. the need for individual privacy

d. keeping diplomatic conversations secret

6. A ________________ requires that the cipher alphabet changes throughout the encryption process.

a. monoalphabetic substitution cipher

b. polyalphabetic substitution cipher

c. quantum cipher

d. alphanumeric shift cipher

7. NP problems have solution times that are __________________.

a. based on guessing and are not predictable

b. always quadratic and are predictable

c. linear

d. based on the number of prime factors

8. Binary numbers obscure the _________ of information.

a. word distribution

b. meaning

c. typing

d. identity

9. As the trustworthiness of a system increases, our __________ decreases.

a. demand for keys

b. confidence

c. risk exposure

d. need for security

10.  The _______ controls the action of the algorithm.

a. user

b. plain text

c. cipher text

d. key

Part II:

Q1 a Complete the following Truth Table: F denotes false and T denotes True

Q1 b In the following Θ denotes one of the following operators: 'or', 'xor' or 'and'.

Input1 Θ input2 = Result   where, input1, 2 are 'A' and 'B' and Result is one of C, D, or E.

which operation will yield

 input1(2) Θ result = input 2(1)

Q2 Using the English alphabet (i.e., mod 26 arithmetic) let plaintext = {p₁, p₂,... , p_n} and corresponding ciphertext = {c₁, c₂,... , c_n}.

Suppose the encryption function is c_i = p_i + 10 (mod 26).  You receive the ciphertext message EWEM SC K QBOKD CMRYYV

What is the decryption function, and the decrypted/recovered plaintext? What type of cipher is this? Show your calculations.

Q3 You are Alice. You have agreed with your friend Bob that you will use the Diffie-Hellman public-key algorithm to exchange secret keys. You and Bob have agreed to use the public base g = 3 and public modulus p = 809.

You have secretly picked the value S_A = 17. You begin the session by sending Bob your calculated value of T_A. Bob responds by sending you the value T_B = 291. 

What is the value of your shared secret key? Can you guess Bob's secret value S_B and what it would be? Show steps of your calculations

Q4 Bob believes that he has come up with a nifty hash function. He assigns a numeric value V_Char to each letter in the alphabet equal to the letter's position in the alphabet, i.e., V_A = 1, V_B = 2, ..., V_Z = 26. For a message, he calculates the hash value H = (V_{Char 1} x V_{Char 2} x V_{Char 3 ...}x V_{Char N}) mod(26).

Bob uses this function to send a one-word message, REGAL, to his banker Bill, along with his calculated hash value for the message. Alice is able to intercept the message, and generates an alternative message that has a hash value that collides with Bob's original hash value.

Give definition and properties of the hash function.

Show a message that Alice may have used to spoof Bob's message, and demonstrate that its hash value collides with Bob's original hash.

Q5 Consider the following plaintext message: THE SIXTEENTH PRESIDENT WAS ABRAHAM LINCOLN.

a. If this message is sent unencrypted and successfully received, what is its entropy? And why?

b. If this message is encrypted with DES using a random 56-bit key, what is the encrypted message's entropy?  And why

Part III

Essay Question.   Length:800- 900 words.  Use APA format for in-line citations and references.

Compare and contrast symmetric and asymmetric encryption algorithms.

• Your response should include a brief overview of the cryptographic basis for each type of algorithm, and a comparison of their relative strengths and vulnerabilities.
• Describe how a hacker might go about cracking a message encrypted with each type of algorithm.
• Suggest a specific application for each type of algorithm where the advantages clearly outweigh the disadvantages.
• Remember to address all points