Cryptography & System Security - Dec 2015

Computer Engineering (Semester 7)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1 (a) Define the following examples
i) Substitution cipher
ii) Poly-alphabetic cipher
iii) Salami attack
iv) Session Hijacking(10 marks) 1 (b) With the help of examples explain non-malicious programming errors.(5 marks) 1 (c) Define the goals of security and specify mechanisms to archive each goal.(5 marks) 2 (a) In an RSA system the public key (e,n) of user A is defined as (7,119). Calculate Φ_n and private key d. what is the cipher text when you encrypt message m=10, using the public key?(10 marks) 2 (b) Give the format of X 509 digital certificate and explain the use of a digital signature in it.(5 marks) 2 (c) Encrypt "The key is hidden under the door" using playfair cipher with keyword "domestic".(5 marks) 3 (a) Explain how a key is shared between two parties using Diffie-Hellman by exchange algorithm. What is the drawback of this algorithm?(10 marks) 3 (b) Differentiate between i) MD-5 and SHA ii) Firewall and IDS.(10 marks) 4 (a) Explain working of DES detailing the Fiestel structure.(10 marks) 4 (b) What is a Denial of service attack. What are the different ways in which an attacker can mount a DOS attack on a sytem?(10 marks) 5 (a) List the functions of the different protocols of SSL. Explain the handshake protocol.(5 marks) 5 (b) How does PGP achieve confidentially and authentication in emails?(5 marks) 5 (c) Differentiate between the transport mode and tunnel mode of IP Sec and explain how authentication and confidentiality are achieved using IP Sec.(10 marks)

Write in brief about (any four):

6 (a) Operating System Security.(5 marks) 6 (b) Buffer overflow attack.(5 marks) 6 (c) IP spoofing(5 marks) 6 (d) Viruses and their types.(5 marks) 6 (e) Key generation in IDEA.(5 marks)