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Reg No.:_ Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SEVENTH SEMESTER B.TECH DEGREE EXAMINATION(S), MAY 2019
Course Code: CS409
Course Name: CRYPTOGRAPHY AND NETWORK SECURITY

Max. Marks: 100 Duration: 3 Hours
PARTA

Answer all questions, each carries 4 marks. Marks
1 How the nonlinearity is achieved in DES. (4)
2 Differentiate Confusion and Diffusion. (4)
3 Discuss the key expansion procedure in AES (4)
4 State and prove Fermat’s Theorem (4)
5 In a public key system using RSA, you intercept the cipher text C=8 sent toa user (4)

whose public key is e=13, n=33. What is the plain text M?

6 Compare the strength of MAC and Encryption against brute-force attack (4)
7 Give the header format of ESP in IPSec (4)
8 Give the authentication methods used in Oakley algorithm (4)
9 What are the services provided by Record Layer Protocol for Secure Socket (4)

Layer connections?
10 What are the characteristic features of stateful inspection firewall? (4)
PART 13
Answer any two full questions, each carries 9 marks.

11 a) Differentiate between monoalphabetic ciphers and polyalphabetic ciphers (5)

and give one example for each.

b) Give different techniques used in steganography (4)
12 a) How key generation is performed in IDEA (4)
b) Discuss Mix Column transformation in AES (5)

13 a) Using rail fence cipher, encrypt the text meet me after the toga party using the (4)
key4312567.

b) Illustrate inverse S box creation in AES. (5)
PART C
Answer any two full questions, each carries 9 marks.
14 a) Find ged(240, 46) using Extended Euclid’s Algorithm (4)
b) Discuss the key exchange procedure using Elliptic Curves. (5)

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