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JE – 840

*JE840*

VIII Semester B.E. (CSE/ISE) Degree Examination, June/July 2013 (2K6 Scheme) CI 8.4.3 : CRYPTOGRAPHY AND NETWORK SECURITY (Elective) Time : 3 Hours

Max. Marks : 100

Instruction : Answer any five questions selecting atleast 2 from each Part. PART – A 1. a) How many keys are required for two people to communicate via a cipher ? Explain the playfair cipher.

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b) List and briefly define types of cryptanalytic attacks based on what is known to the attacker ?

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c) Explain one time pad technique.

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2. a) Why it is important to study the Feistel cipher ? Explain with a neat diagram, Feistel encryption and decryption. 10 b) In detail, explain the Blowfish single round. 3. a) Explain the Meet-in-the-middle attack. b) Define the following terms : i) Random number ii) Pseudo random number iii) Public key and private key iv) Master key and session key v) Steganography. c) Prove the Fermat’s theorem. 4. a) What requirements must a public key cryptosystem fulfill to be a secure algorithm ? Explain. b) Explain the Euler’s theorems.

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P.T.O.

*JE840*

JE – 840 PART – B

5. a) Explain how authentication and confidentiality is provided by Hash function. b) What are the properties a digital signature should have ? c) Explain how message digest is generated using MD5. 6. a) Explain how digital signature is generated by DSS approach. b) Explain the role of Kerberos in authentication. 7. a) Explain the SSL architecture. b) Explain the IPsecurity Architecture. 8. Write a note on :

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(5×4=20)

a) Pretty Good Privacy. (PGP) b) Viruses and related threats. c) X.509 standard. d) Firewall. __________________