# NPTEL Cyber Security and Privacy Week 8 Assignment Answer 2023

NPTEL Cyber Security and Privacy Week 8 Assignment Solutions

## NPTEL Cyber Security and Privacy Week 8 Assignment Answer 2023

1. Which of the following terms describes the process of making and using codes to secure the transmission of information?

• Algorithm
• Cryptography
• Steganography
• Cryptanalysis
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2. 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
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3. 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
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4. 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
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5. 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
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6. Limited-use symmetric keys for temporary communications during an online session is called

• Session keys
• AES
• DES
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7. 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
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8. 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(N1)/2
• (N-1)2
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9. 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
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10. ————security protocols are used to protect e-mail

• SMTP
• HTTPS
• S/MIME, PEM, and PGP
• Telnet
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11. What is the most popular encryption system used over the Web?

• Diffie Hellman key exchange
• RSA
• Block cipher
• DES
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