Kannur University 2007 M.C.A Computer Aplications C 4.4 CRYPTOGRAPHY AND NETWORK SECURITY - Question Paper

Fourth Semester M.C.A Degree Examination,November 2007
MCAC 4.4 CRYPTOGRAPHY AND NETWORK SECURITY
Time:3 Hours Max.Marks :80

Instructions: 1)Answer 5 ques.
2)All ques. carry equal marks (16x5=80)


1.Write Euclid algorithm to obtain gcd of two numbers a and b.?Prove that algorithm always provide gcd in a finite number of steps.Find multiplicative inverse of 286 mod 1575 if exists.

2.Briefly discuss block cipher modes of operation.

3.Explain criteria used in AES valuation.

4,With suitable diagram discuss the key schedule in DES algorithm.

5.Differentiate ranging from cryptography and cryptanalysis.Using an affine transformation C=aP+b(mod m) wher P and C are plain and cipher text messages in English language and with a=4,b=5 and m=26.Find the transformed message for “YOU ARE ALL GOOD STUDENTS”.

6.What are the requirements of authentication and hence group authentication functions.

7.Breiefly discuss Secure hash algorithm.

8.Explain password selection strategies.

Earning:   Approval pending.