54115-mt----network Security & Cryptography

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Code No: 54115/MT M.Tech. – I Semester Supplementary Examinations, September, 2008

NETWORK SECURITY & CRYPTOGRAPHY (Common to Digital Systems & Computer Electronics/ Digital Electronics & Communication Systems/ Information Technology) Time: 3hours

Max. Marks:60 Answer any FIVE questions All questions carry equal marks ---

1.a) b)

Describe the security mechanism defined in X.800 What is transposition cipher? Explain the encryption process with an example.

2.a) b) c)

Describe S-DES encryption algorithm. Describe the avalanche effect in DES. What are the characteristics of advanced symmetric block ciphers?

3.a) b)

Describe key distribution technique. Describe Diffie-Hellman key exchange algorithm.

4.a)

Describe an attractive and popular algorithm to determine whether the given number is prime. Illustrate different ways in which a hash code can be used to provide message authentication.

b) 5.a) b) c) 6.a) b) c) 7.a) b) c) 8.

Describe the steps involved in secure hash algorithm (SHA-I) What is the difference between direct and arbitrated digital signature? What are the differences in crypto system and digital signature? What are the principal difference between versions 4 and versions 5 for kerberos? What are the technical deficiencies of kerberos version 4 protocol? Describe X.509 alternative authentication procedures. What are the issues in Web Security? Distinguish between transport mode and tunnel mode encryption in the IPSec ESP service. Explain the key management portion of IPSec. Write short notes on: a) Pretty Good Privacy b) Firewall design principles c) Message authentication. $$$