PART–A (22 Marks)                 

1. a) What is meant by buffer overflow? [4]       b) Explain Cipher Block Chaining Mode.           [4]
2. What is Eulers Totient function? Find it for 37 and 21. [4]
3. What is data authentication code? [3]
4. List the transfer encodings used by S/MIME. [4]
5. What is meant by packet sniffing? [3]

                                                    PART–B (3x16 = 48 Marks)           

2. a) Explain the operations, requirements, components of Network security model. [8]       b) What is TCP Session Hijacking? How is it done?    [8]

3. a) Give a detailed description of key generation and encryption of IDEA algorithm [8]       b) Explain about CAST-128 encryption algorithm.             [8]

4. a) What is discrete logarithm? What are their properties? [8]
5. b) Using RSA algorithm, Find n, d if  p=11, q=3, e=3. Encrypt “HelloWorld”                                                      

                 Message.                                                                                     [8]

5. a) Describe HMAC algorithm. Comment on the security of HMAC. [8]       b) Describe signing and verification in Digital Signature Algorithm.            [8]

6. a) Write about the usage of session keys, Public and Private keys in PGP. [8]       b) Give the structure of PGP message generation. Explain with a diagram. [8]

7. a) What is meant by Transport mode and tunnel mode? How is authentication  

header implemented in these two modes?    [8]       b) What is rule based Intrusion Detection?          [8]

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                                                        PART–A (22 Marks)                          

1. a) What is the web based attacks?          [3]       b) What are the disadvantages of double DES?     [4]
   1. State Euler’s Theorems. [3]
   2. What is meant by one-way property in hash function? [4]
   3. What is the problem that kerberos addresses? [4]
   4. What is meant by intrusion detection system? [4]

                                                  PART–B (3x16 = 48 Marks)                    

2. a) Differentiate between passive attacks and active attacks.            [8]       b) Discuss about TCP session hijacking and UDP hijacking.       [8]

3. a) Describe Triple DES and its applications.                 [8]       b) Discuss in detail about Blowfish.             [8]

4. a) Describe RSA Algorithm and Estimate the encryption and decryption values for         

             the RSA algorithm parameters.                                                    [8]

1. State the Chinese Remainder Theorem and find X for the given set of congruent  

            equations X≡2 mod 3, X≡3 mod 5 and X≡2 mod 7.                     [8]

5. a) What are the types of attacks addressed by message authentication? What are two       

levels of functionality that comprise a message authentication or digital signature  mechanism?          [8]

1. Explain the process of deriving eighty 64-bitwords from 1024 bits for processing  

        of a single blocks and also discuss single round function in SHA-512 algorithm.                                                           

             Show the values of W16, W17, W18 and W19.                           [8]

6. a) How does PGP provide authentication and confidentiality for email services and for file transfer applications? Draw the block diagram and explain the         [8]
   1. Analyze the Cryptographic algorithms used in S/MIME and Explain S/MIME

              certification processing.                                                               [8]

7. a) Explain IP Security protocols in detail.         [8]       b) Write short notes on Signature based IDS.     [8]

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