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Reg No.: Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SEVENTH SEMESTER B.TECH DEGREE EXAMINATION, DECEMBER 2018

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 Differentiate between computationally secure cipher and unconditionally secure (4)

cipher. Write examples with reasoning.
2 Encrypt the message “‘this is an exercise” using the additive Cipher with key=20 (4)
3 What is the necessity of block cipher modes of operation? List out the (4)
advantages and disadvantages of output feedback mode.
4 Generate the key attributes for the values p = 11 and ‏و‎ = 3. Also encrypt the (4)

message m = 2 with the generated keys.

5 Find ged (1970, 1066) (4)

6 Discuss digital signature scheme using RSA (4)

7 Write the general structure of Private Key Ring used in Pretty Good Privacy (4)
(PGP).

8 What are the functionalities provided by Secure MIME (S/MIME)? (4)

9 What is the significance of Alert Protocol in Transport Layer Security? (4)

10 Why the attacker is not able to recognize the actual sender of the message 1 (4)

encrypted tunnels?

PART 8
Answer any two full questions, each carries 9 marks.

11 ஐ Use Playfair Cipher with key COMPUTER to encrypt the message (5)

“CRYPTOGRAPHY”.
b) How key generation is done in DES. (4)
12 a) Discuss the stream cipher RC4 in detail (4)
0) Illustrate the round transformation of IDEA. (5)
13 9) Encrypt the text “LOVE” using Hill Cipher with the key ९ 1 (4)
b) Illustrate 5 box creation in AES (5)

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