Download GTU B.Tech 2020 Summer 8th Sem 2170709 Information And Network Security Question Paper

Enrollment No._______

BE - SEMESTER- VIII EXAMINATION - SUMMER 2020

Subject Code: 2170709 Date:27/10/2020

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Subject Name: Information and Network Security

Time: 10:30 AM TO 01:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.
2. Make suitable assumptions wherever necessary.

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3. Figures to the right indicate full marks.

MARKS

Q.1 (a) Define the terms: Confidentiality, Data integrity, Non-repudiation 03

(b) Construct a Playfair matrix with the key “engineering”. And encrypt the message “impossible”. 04

(c) Define Cryptography and Cryptanalysis. Draw and explain conventional cryptosystem. 07

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Q.2 (a) Write the differences between conventional encryption and public key encryption. 03

(b) Write a note on Hill Cipher. 04

(c) Explain the key generation in DES algorithm. 07

OR

(c) Explain the key generation in AES algorithm. 07

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Q.3 (a) What is the purpose of the S-boxes in DES? Explain the avalanche effect. 03

(b) Explain Cipher Block Chaining (CBC) and Electronic Code Book (ECB) block cipher modes of operation with the help of diagram. 04

(c) Explain X.509 authentication service. 07

OR

Q.3 (a) What is the difference between a session key and a‘master key? 03

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(b) Explain Cipher Feedback (CFB) and Output Feedback mode (OFB) block cipher modes of operation with the help of diagram. 04

(c) Explain authentication mechanism of Kerberos. 07

Q.4 (a) What characteristics are needed in a‘secure hash function? 03

(b) In a public key system using RSAythe cipher text intercepted is C=10 which is sent to the user whose public key is‘e=5, n=35. What is the plaintext M? 04

(c) What do you mean by key/distribution? Give at least one method for key distribution with proper illustration. 07

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OR

Q.4 (a) What is the purpose of the State array? How many bytes in State are affected by ShiftRows? 03

(b) Is message authentication code same as encryption? How message authentication can be done by message authentication code? 04

(c) Briefly explain Diffie-Hellman key exchange. Is it vulnerable to man in the middle attack? Justify. 07

Q.5 (a) Using the Vigencre cipher, encrypt the word “ATTACKATDAWN?” using the key “LEMON”. 03

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(b) Write a note on HTTPS. 04

(c) Write a short note on “Digital Signature Algorithm”. 07

OR

Q.5 (a) Explain basic Hash code generation. 03

(b) How public keys can be distributed. 04

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(c) Explain SSL architecture. 07

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