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TU BCA 8th Semester — 2023, 2022 BOARD EXAM — Information Security MCQs

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TRIBHUVAN UNIVERSITY

Bachelor of Computer Application

OFFICE OF THE DEAN

2023, 2022 BOARD EXAM

Faculty: Bachelor of Computer Application (BCA)

Course Title: Information Security (MCQs)

Code No: CACS453

Semester: 8th Semester

Full Marks: 60

Pass Marks: 24

Time: 3 hours

Group A (Multiple Choice Questions)

Attempt all questions. Correct answers are highlighted in yellow.

1.Which of the following process can convert cipher text to plain text?

Hashing

Encryption

Decryption

✓ Correct Answer

Substitution

💡 Complete Solution & Explanation:

Decryption is the process of converting cipher text (encrypted data) back to plain text using a decryption key or algorithm.

2.Which of the following concept is not part of CIA triad?

Confidentiality

Integrity

Authenticity

✓ Correct Answer

Availability

💡 Complete Solution & Explanation:

The CIA triad consists of Confidentiality, Integrity, and Availability. Authenticity is a separate security principle not part of the CIA triad.

3.How many rounds does AES-256 perform?

✓ Correct Answer

💡 Complete Solution & Explanation:

AES-256 performs 14 rounds of encryption operations, whereas AES-128 performs 10 rounds and AES-192 performs 12 rounds.

4.What is multiplicative inverse of $7$ in $\mathbb{Z}_{11}$ ?

✓ Correct Answer

💡 Complete Solution & Explanation:

\mathbb{Z}_{11}

, the multiplicative inverse of

7

8

because

(7 \times 8) \pmod{11} = 56 \pmod{11} = 1

5.What does a message authentication code (MAC) provide?

Confidentiality of the message

Integrity and authenticity of message

✓ Correct Answer

Encryption message

Decryption of message

💡 Complete Solution & Explanation:

MAC ensures that the message hasn't been tampered with (integrity) and verifies the sender's identity (authenticity).

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6.Which of the following is a vulnerability of password-based authentication?

Passwords can be easily shared

✓ Correct Answer

Passwords are too complex to remember

Passwords are always encrypted

Passwords are never exposed to attackers

💡 Complete Solution & Explanation:

One major vulnerability of password-based authentication is that passwords can be easily shared between users, compromising security.

7.Which of the following is not a typical component of an IDS?

Sensors

Analysis engine

Response system

Antivirus software

✓ Correct Answer

💡 Complete Solution & Explanation:

Antivirus software is a separate security tool and not a typical component of an Intrusion Detection System (IDS).

8.Which mode of IPSec provides encryption and authentication for the entire IP packet?

Transport mode

Tunnel mode

✓ Correct Answer

Application mode

Network mode

💡 Complete Solution & Explanation:

Tunnel mode encrypts and authenticates the entire IP packet, including the original IP header, providing complete packet protection.

9.Which of the following type of firewall work on the basis of rules defined by Access Control List?

Packet filtering Firewall

✓ Correct Answer

Circuit level gateway Firewall

Next generation Firewall

Application Level gateway Firewall

💡 Complete Solution & Explanation:

Packet filtering firewalls operate based on predefined rules in Access Control Lists (ACLs) to allow or deny network traffic.

10.Which of the following is typically not a phase in a security audit process?

Planning and scoping

Information gathering

Performance review

✓ Correct Answer

Reporting and follow-up

💡 Complete Solution & Explanation:

Performance review is not a typical phase in security auditing, which focuses on security assessment rather than performance evaluation.

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11.Which of the following is not category of active attack?

Masquerade

Replay

Modification of Message

Traffic analysis

✓ Correct Answer

💡 Complete Solution & Explanation:

Traffic analysis is a passive attack (observes patterns only). Active attacks involve altering or injecting data.

12.Which cipher is best known diagraph substitution cipher?

Ceasar cipher

Vigenere cipher

Playfair Cipher

✓ Correct Answer

Shift Cipher

💡 Complete Solution & Explanation:

The Playfair cipher substitutes pairs of letters (digraphs), making it the classic and best-known digraph substitution cipher.

13.In asymmetric cryptography, who is kept private key?

Receiver

✓ Correct Answer

Sender

Both sender and receiver

All the connected devices to the network.

💡 Complete Solution & Explanation:

For confidentiality, the sender uses the receiver's public key and only the receiver keeps the private key to decrypt.

14.How many bytes are required to store SHA-1 hash value?

32 byte

20 byte

✓ Correct Answer

64 byte

16 byte

💡 Complete Solution & Explanation:

SHA-1 produces a 160-bit digest, which equals

20

bytes (

160 \div 8

15.Which one of the following produces a signature for the document?

Key generation algorithm.

Signature verifying algorithm

Signing algorithm

✓ Correct Answer

authentication

💡 Complete Solution & Explanation:

The digital signature is created by the signer's private key using the signing algorithm; verification uses a different algorithm.

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16.Which of the following is the least secure method of authentication?

Key card

Fingerprint

Retina pattern

Password

✓ Correct Answer

💡 Complete Solution & Explanation:

Knowledge-based passwords are easily guessed, reused, or phished, making them weaker than biometrics or tokens.

17.Which of the following process is used for verifying identity of user?

Authentication

✓ Correct Answer

Identification

Validation

verification

💡 Complete Solution & Explanation:

Authentication confirms that a user is who they claim to be (e.g., via password, token, or biometrics).

18.What are different ways to classify an IDS?

Zone based

Host and Network based

✓ Correct Answer

Network and Zone based

Level based

💡 Complete Solution & Explanation:

IDSs are commonly categorized as Host-Based (HIDS) and Network-Based (NIDS).

19.A firewall protects which of following attacks?

Phishing

Dumpster diving

Denial of Service (DoS)

✓ Correct Answer

Shoulder surfing

💡 Complete Solution & Explanation:

Firewalls mitigate many network-borne attacks and can filter/block traffic patterns used in DoS; the other options are social/physical attacks.

20.Which of the following software module periodically extracts record from the audit trail to create archive of auditable events?

Audit analyzer

Audit archiver

✓ Correct Answer

TU BCA 8th Semester — 2023, 2022 BOARD EXAM — Information Security MCQs

TRIBHUVAN UNIVERSITY

OFFICE OF THE DEAN

Group A (Multiple Choice Questions)

1.Which of the following process can convert cipher text to plain text?

2.Which of the following concept is not part of CIA triad?

3.How many rounds does AES-256 perform?

4.What is multiplicative inverse of 777 in Z11\mathbb{Z}_{11}Z11​?

5.What does a message authentication code (MAC) provide?

6.Which of the following is a vulnerability of password-based authentication?

7.Which of the following is not a typical component of an IDS?

8.Which mode of IPSec provides encryption and authentication for the entire IP packet?

9.Which of the following type of firewall work on the basis of rules defined by Access Control List?

10.Which of the following is typically not a phase in a security audit process?

11.Which of the following is not category of active attack?

12.Which cipher is best known diagraph substitution cipher?

13.In asymmetric cryptography, who is kept private key?

14.How many bytes are required to store SHA-1 hash value?

15.Which one of the following produces a signature for the document?

16.Which of the following is the least secure method of authentication?

17.Which of the following process is used for verifying identity of user?

18.What are different ways to classify an IDS?

19.A firewall protects which of following attacks?

20.Which of the following software module periodically extracts record from the audit trail to create archive of auditable events?

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TU BCA 8th Semester — 2023, 2022 BOARD EXAM — Information Security MCQs

TRIBHUVAN UNIVERSITY

OFFICE OF THE DEAN

Group A (Multiple Choice Questions)

1.Which of the following process can convert cipher text to plain text?

2.Which of the following concept is not part of CIA triad?

3.How many rounds does AES-256 perform?

4.What is multiplicative inverse of 777 in Z11\mathbb{Z}_{11}Z11​?

5.What does a message authentication code (MAC) provide?

6.Which of the following is a vulnerability of password-based authentication?

7.Which of the following is not a typical component of an IDS?

8.Which mode of IPSec provides encryption and authentication for the entire IP packet?

9.Which of the following type of firewall work on the basis of rules defined by Access Control List?

10.Which of the following is typically not a phase in a security audit process?

11.Which of the following is not category of active attack?

12.Which cipher is best known diagraph substitution cipher?

13.In asymmetric cryptography, who is kept private key?

14.How many bytes are required to store SHA-1 hash value?

15.Which one of the following produces a signature for the document?

16.Which of the following is the least secure method of authentication?

17.Which of the following process is used for verifying identity of user?

18.What are different ways to classify an IDS?

19.A firewall protects which of following attacks?

20.Which of the following software module periodically extracts record from the audit trail to create archive of auditable events?

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4.What is multiplicative inverse of $7$ in $\mathbb{Z}_{11}$ ?

4.What is multiplicative inverse of $7$ in $\mathbb{Z}_{11}$ ?