Assignment:
Instructions
The question below are in two parts. Part 1 is multiple choice questions, highlight in yellow the correct answer(s) in each question. For Part 2, give a detailed answer to the question, shows calculation on how you arrived at your answers in question 3 of Part 2.
Part 1: Multiple Choice Questions. Note Unless specified otherwise all multiple choice questions have only one correct answer.
General questions
1. Choose all right statements:
A) A principal concept in both the OSI and TCP/IP model is layering.
B) A principal concept in both the OSI and TCP/IP model is controlling.
C) Layering is a structuring technique to manage complexity and evolution.
D) Controlling is a structuring technique to manage complexity and evolution.
E) None of the above.
2. There are core aspects or properties to security: Choose all right statements:
A) Confidentiality: Accessed only by authorized parties
B) Availability: Accessible to unauthorized parties at appropriate time
C) Integrity: Modified by unauthorized parties only in authorized ways
D) Availability: Accessible to authorized parties at appropriate time
E) None of the above.
3. Choose all right statements:
A) Authenticity: A message is genuine but from unauthorized parties.
B) Accountability: Availability of an action to the party that is responsible for causing it.
C) Authenticity is considered a dimension of confidentiality, since the definition of confidentiality permits changes to information only by authorized parties.
D) Accountability: Confidentiality of an action to the party that is not responsible for causing it.
E) None of the above.
4. Choose all right statements:
A) The Three Ds of Security are deterrences, detections, and defensive controls.
B) Deterrenc is the first mode of security since it "reduces the likelihood of security compromise"
C) Detection is the second mode of security since it "reduces the frequency of security compromises".
D) Examples of defensive control mechanisms are virus filters, firewalls, spam filters, router access lists, and static routes.
E) None of the above.
Cryptography Fundamentals. Public-Key Cryptography and Message Authentication
5. The two methods of encrypting data are
A) Substitution and transposition
B) Block and stream
C) Symmetric and asymmetric
D) DES and AES
6. The only cipher system said to be unbreakable by brute force is
A) AES
B) DES
C) One-time pad
D) Triple DES
7. When a user needs to provide message integrity, what options may be the best?
A) Send a digital signature of the message to the recipient
B) Encrypt the message with a symmetric algorithm and send it
C) Create a checksum, append it to the message, encrypt the message, then send it to the recipient
D) Encrypt the message with a private key so the recipient can decrypt with the corresponding public key
8. Consider the following protocol that involves both RSA public-key operations and DES. Suppose that A has an RSA private key prv(A) and an RSA public key pub(A). Suppose that B has an RSA private key prv(B) and an RSA public key pub(B). Assume both A and B knows each other's public key. A wants to send B some message M. A selects random DES key K and send B the following two messages:
-- Epub(B)( K, Sigprv(A)(K))
-- EK(M)
"E" means encryption and "Sig" means digital signature. Which of the following statement(s) is true? (Choose two.)
A) Only B can decipher the contents of the message M.
B) B is certain that the message M is from A.
C) B can prove to a third party that the message M arrived from A.
D) B cannot decipher the contents of the message M.
E) B is not certain that the message M is from A.
9. Suppose a user is authenticated based on an ID and password that are supplied by the transmitter in plaintext. Does it make any difference if the password and ID are encrypted?
A. If the system authenticates users based on IDs and passwords that are transmitted in plaintext, the system is very insecure.
B. If the password and ID are encrypted, the system is definitely more secure than in the plaintext case.
C. The intruder can still record the encrypted ID and the corresponding encrypted password. By replaying these, the intruder can gain access to the system.
D. None of the above is correct.
10. You have an issue in your company with users claiming they did not receive e-mail messages, while other users claim they were sent. What PKI component will help you to prove the dates and times of messages sent on the network?
A) Non-Repudiation
B) Encryption
C) Encapsulation
D) Integrity
E) Confidentiality
11. A certificate authority provides what benefits to a user?
A) Protection of public keys of all users
B) History of symmetric keys
C) Proof of nonrepudiation of origin
D) Validation that a public key is associated with a particular user
Network Vulnerabilities, Attacks and Countermeasures
12. The following are types of cyber attack: (Choose all correct answers.)
A) A nuclear Electromagnetic Pulse (EMP) attack that knocks out electronic devices.
B) An attacker sends falsified (spoofed) Address Resolution Protocol (ARP) messages onto a local area network.
C) Malicious software designed to interrupt services., see Session 5 session notes)
D) A flood of computers hacked to disrupt other computers.
E) None of the above.
13. If you notice that the number of existing half-open sessions is beginning to rise, what could this indicate? (Select all that apply)
A) Answers
B) Man in the Middle attack
C) Serial Scan
D) IP Spoofing
E) Port Scan
F) DoS attack
14. DoS attacks exist for which part of the OSI protocol stack?
A) Application and Presentation
B) Session and Transport
C) Network and Data Link
D) All of the above
15. Consider using HCP. What are the major security concerns? Indicate the two best answers from the following list.
A) Anyone hooking up to the network can automatically receive a network address.
B) Clients might be redirected to an incorrect DNS address.
C) The network is vulnerable to man-in-the-middle attacks.
D) There are no security concerns with using DHCP.
Part 2: Please give detailed answers to the questions below:
1. Can two network interfaces have the same IP address? Why or why not?
2. Consider the following hashing algorithm. A binary block of length M is divided into subblocks of length 128 bits, and the last block is padded with zeros to a length of 128. The hash consists of the XOR of the resulting 128-bit vectors. Is this algorithm appropriate for encryption? Explain. .
3. Alan and Bill agree (through a public exchange) on using the Diffie-Hellman algorithm to create a common secret key. They also agree on two public numbers: q (large prime number), a (generator mod q): q = 13, a = 3
Alan generates a random RA =11.
Bill generates a random RB =19.
Note you need to show the calculation procedures step by step in (a)-(d).
a. What is the SA Alan sends to Bill ? (i.e. SA =? .
b. What is the SB Bill sends to Alan? (i.e. SB =? .
c. Show how Alan can calculate to obtain a common secret key. What is the common secret key?
d. Show how Bill can calculate to obtain a common secret key. What is the common secret key?