Ethical Hacking Week 6 Assignment Answers

Course Link: https://onlinecourses.nptel.ac.in/noc23_cs44/course

Q1. Which of the following statement is true for Masquerade attack?
a. In this attack, an attacker passively captures a transaction and its reply.
b. In this attack, some portion of message is altered on its way.
c. In this attack, an attacker prevents access of resource to its legitimate users.
d. In this attack, the attacker pretends as a legitimate entity.
e. In this attack, the attacker analyzes the network traffic.

Q2. Which of the following statement(s) is/are true?
a. In private key encryption, separate keys are used by sender and receiver.
b. In private key encryption, a single key is used by sender and receiver.
c. In public key encryption, separate keys are used by sender and receiver.
d. In public key encryption, a single key is used by sender and receiver.

Q3. Consider the following statement:
(i) In symmetric key cryptography, the security depends on secrecy of the key.
(ii) In symmetric key cryptography, the security depends on encryption/decryption algorithm.
a. Only (i) is true
b. Only (ii) is true
c. Both (i) and (ii) are true.
d. Both (i) and (ii) are false.

Q4. 25 parties want to exchange messages securely. The number of distinct key required by a symmetric key encryption algorithm and public key encryption technique like RSA will be _____ and ____ respectively.
a. 25 and 50
b. 50 and 50
c. 100 and 50
d. 300 and 25
e. 300 and 50

Q5. How will be the plaintext for the cipher text “LETTY CEIV” encrypted using a substitution cipher
approach, where each letter is replaced by the k-th next letter. (Assumption: (i) the alphabets
are wrapped around, i.e. Z is followed by A, (ii) each alphabets (A to Z) is assigned a number (1
to 26), (iii) the value of secrete key k is 4).
a. HAPPY YEAR
b. HAPPU YAER
c. HAPPY YEAR
d. None of these

Q6. In data encryption standard (DES), longer plain text are processed in _______ bit blocks.

64

Q7. The effective key lengths used in AES encryption algorithms can be:
a. 64 bit
b. 128 bit
c. 192 bit
d. 256 bit
e. 512bit

Q8. For decryption using public-key cryptography _______ is used.
a. Receivers public key
b. Receiver’s private key
c. Sender’s public key
d. Sender’s private key

Q9. Which of the following statement(s) is/are true.
a. The security of RSA algorithm is dependent on prime factorization problem.
b. RSA algorithm is vulnerable to man-in-the middle attack.
c. Diffie-Hellman approach can be used for encryption/decryption of message.
d. Symmetric encryption approaches are faster than asymmetric encryption.
e. None of these.

Q10. Which of the following techniques cannot be used for message authentication?
a. Conventional encryption approach such as private key.
b. MD4
c. SHA-256
d. SHA-0
e. RIPEMD-128