# Cyber Security and Privacy | Week 8

Session: JULY-DEC 2023

Course Name: Cyber Security and Privacy

#### These are Cyber Security and Privacy Nptel Week 8 Assignment 8 Answers

Q1. Which of the following terms describes the process of making and using codes to secure the transmission of information?
Algorithm
Cryptography
Steganography
Cryptanalysis

Q2. What is term is used to describe a cryptographic method that incorporates mathematical operations involving both a public key and a private key to encipher or decipher a message?
Private-key encryption
Symmetric encryption
Asymmetric encryption

These are Cyber Security and Privacy Nptel Week 8 Assignment 8 Answers

Q3. A substitution cipher that incorporates two or more alphabets in the encryption process is called——————-
Monoalphabetic substitution
Block cipher substitution
Stream cipher substitution
Polyalphabetic substitution

Q4. The current standard for the encryption of data, as specified by NIST ——— is based on the Rijndael algorithm, which was developed by Vincent Rijmen and Joan Daemen.
DES
RSA
AES
Message Digest

These are Cyber Security and Privacy Nptel Week 8 Assignment 8 Answers

Q5. True or False:
Nonrepudiation means that customers or partners can be held accountable for transactions, such as online purchases, which they cannot later deny.

True
False

Q6. Limited-use symmetric keys for temporary communications during an online session is called
Session keys
AES
DES

These are Cyber Security and Privacy Nptel Week 8 Assignment 8 Answers

Q7. Match the following

A-3, B-5, C-4, D-1, E-2
A-2, B-1, C-4, D-5, E-3
A-4, B-2, C-3, D-1, E-1
A-5, B-2, C-3, D-1, E-4

Answer: A-2, B-1, C-4, D-5, E-3

These are Cyber Security and Privacy Nptel Week 8 Assignment 8 Answers

Q8. Suppose that everyone in a group of N people wants to communicate secretly with the N-1 others using a symmetric key cryptographic system. Communication between any two persons should not be decodable by others in the group. The number of keys required in the system as a whole to satisfy the confidentiality requirement is
2N
N(N-1)
N(N-1)/2
(N-1)2

Q9. Decrypt the following message if it was encrypted using a shift cipher with a shift of 3.
Message: NPTELINFORMATION

Q S W H O L Q I R U P W L R Q
Q S W H O L Q I T U P W L R Q
Q S W F O L Q I R V P W L R Q
Q S W H O L Q I R V P W L R Q

Answer: Q S W H O L Q I R U P W L R Q

These are Cyber Security and Privacy Nptel Week 8 Assignment 8 Answers

Q10. ————security protocols are used to protect e-mail
SMTP
HTTPS
S/MIME, PEM, and PGP
Telnet

Q11. What is the most popular encryption system used over the Web?
Diffie Hellman key exchange
RSA
Block cipher
DES