DATA COMPRESSION AND ENCRYPTION (DCE) MAY 2009 [ELECTIVE] ELECTRONICS AND TELECOMMUNICATION SEMESTER 7

DATA COMPRESSION AND ENCRYPTION (DCE) MAY 2009 [ELECTIVE]  ELECTRONICS AND TELECOMMUNICATION SEMESTER 7

                                                      
                                                                      (3 Hours)                            [Total Marks:-100]

N.B:- (1) Question No.1 is compulsory.
          (2) Attempt any four out of remaining six questions.

1. (a) Distinguish between Scalar and Vector quantization. [5 Marks]
    (2) What is 'motion compensation' in video compression? [5 Marks]
    (3) Compare symmetric and public key cryptography. [5 Marks]
    (4) Classify security attacks and discuss them. [5 Marks]

2. (a) Draw the Adaptive Huffman tree for the string 'xyxwz'... Give the encoding and decoding
         process for the same. [10 Marks] 
    (b) Explain the working of DES. [10 Marks]

3. (a) Encode the string 'mnop mnop ponm' using LZ78. What are the limitations of this method?
         How does LZW overcome this limitations? [10 Marks]
    (b) What is the significance of prime numbers in cryptography? Explain RSA algorithm with a
          suitable example. [10 Marks]

4. (a) Describe various approaches for image compression and discuss one of them in
         detail. [10 Marks]
   (b) Explain the Diffie-hellman key exchange process. [10 Marks]

5. (a) Explain significance of modelling and coding with respect to data compression. Discuss the
         various popular models used. [10 Marks]
    (b) Discuss security of HASH and MAC functions. [10 marks]

6. (a) What are the various applications for the Run Length Encoding(RLE) compression
          scheme? [10 Marks]
    (b) What are the main features of Digital Signature? Discuss one if its algorithm. [10 Marks]

7. Write notes on any two:- [20 Marks]
     (a) MPEG Audio
     (b) Discrete Logarithm
     (c) Stream Ciphers
     (d) Arithmetic Coding