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Code No: RR410504 Set No. 1
IV B.Tech I Semester Supplementary Examinations, March 2006NETWORK SECURITY AND CRYPTOGRAPHY
(Computer Science & Engineering)Time: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. Write short notes on
(a) Symmetric model [4M]
(b) Cryptography [4M]
(c) Cryptanalysis [4M]
(d) Steganography [4M]
2. (a) List the characteristics of advanced block ciphers. [8M]
(b) What are the differences between RC5 and RC2? [8M]
3. (a) Illustrate Diffie-hellman Key Exchange scheme for GF(P) [6M]
(b) Consider a diffie-helman scheme with a common prime q=11 and a primitiverootα=2
i. If user A has public key YA = 9, what is A’s private key XA ?
ii. If user B has public key YB = 3, what is the shared key K? [10M]
4. Given 2 as a primitive root of 29, construct a table of indices, and use it to solvethe following congruences:
(a) 17x2≡ 10 mod 29
(b) x2−4x − 16 ≡ 0 mod 29
(c) x7≡ 17 mod 29 [5+5+6]
5. (a) what are digital signature standards?
(b) Explain Digital signature algorithm. [8+8]
6. (a) What problem was Kerberos designed to address?
(b) What are three threats associated with user authentication over a network orInternet?
(c) List three approaches to secure user authentication over a network or Internet?
[4+4+8]
7. (a) What is replay attack?
(b) Why does ESP include a padding field? [6+10]
8. (a) what information used by a typical packet-filtering router?
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Code No: RR410504 Set No. 1
(b) What are some weaknesses of a packet-filtering router?
(c) What is the difference between a packet-filtering router and a stateful inspec-tion firewall? [8+4+4]
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Code No: RR410504 Set No. 2
IV B.Tech I Semester Supplementary Examinations, March 2006NETWORK SECURITY AND CRYPTOGRAPHY
(Computer Science & Engineering)Time: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) What is Steganography? [6M]
(b) Explain various modes of operations of block ciphers [10M]
2. (a) List the characteristics of advanced block ciphers. [8M]
(b) What are the differences between RC5 and RC2? [8M]
3. (a) Explain the process encryption and decryption in Elliptic curve cryptography?[8M]
(b) Explain the additive rules of Elliptic Curve Cryptography? [8M]
4. (a) Explain Chinese Remainder Theorem.
(b) State and prove Euler’s theorem?
(c) Using Fermat’s theorem, find 201 mod 11. [5M+5M+6M]
5. (a) What is a message authentication code?
(b) What is difference between message authentication code and a one-way hashfunction?
(c) In what ways can a hash value be secured so as to provide message authenti-cation?
[5+5+6]
6. (a) What is R64 conversion?
(b) Why is R64 conversion useful for an e-mail application?
(c) Why is the segmentation and reassembly function in PGP needed? [4+6+6]
7. Write a short note on
(a) Electronic mail Services
(b) Firewalls [8+8]
8. (a) what information used by a typical packet-filtering router?
(b) What are some weaknesses of a packet-filtering router?
(c) What is the difference between a packet-filtering router and a stateful inspec-tion firewall? [8+4+4]
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campusexpress.co.in
campu
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Code No: RR410504 Set No. 3
IV B.Tech I Semester Supplementary Examinations, March 2006NETWORK SECURITY AND CRYPTOGRAPHY
(Computer Science & Engineering)Time: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) What are the various components of symmetric cipher model? Explain. [8M]
(b) Write short notes on crypto analysis. [8M]
2. (a) List the characteristics of advanced block ciphers. [8M]
(b) What are the differences between RC5 and RC2? [8M]
3. (a) What is a one-way function?
(b) What is trap-door one-way function?
(c) Describe in general terms an efficient procedure for picking a prime number?
[5+5+6]
4. Given 2 as a primitive root of 29, construct a table of indices, and use it to solvethe following congruences:
(a) 17x2≡ 10 mod 29
(b) x2−4x − 16 ≡ 0 mod 29
(c) x7≡ 17 mod 29 [5+5+6]
5. (a) What is the difference between weak and strong collision resistance?
(b) What is the role of a compression function in a hash function? [6+10]
6. Explain X.509 Authentication services [16]
7. (a) List and briefly define the parameters that define an SSL session state?
(b) List and briefly define the parameters that define an SSL session connection?
[8+8]
8. (a) what information used by a typical packet-filtering router?
(b) What are some weaknesses of a packet-filtering router?
(c) What is the difference between a packet-filtering router and a stateful inspec-tion firewall? [8+4+4]
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Code No: RR410504 Set No. 4
IV B.Tech I Semester Supplementary Examinations, March 2006NETWORK SECURITY AND CRYPTOGRAPHY
(Computer Science & Engineering)Time: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) What are differences between a block cipher and a stream cipher? [8M]
(b) Explain various modes of operations of block ciphers. [8M]
2. (a) List the characteristics of advanced block ciphers. [8M]
(b) What are the differences between RC5 and RC2? [8M]
3. (a) Consider the Elliptic curve E11 (1,6) that is , the curve is defined by y2 =
x3 + x + 6 with a modulus of P=11.Determine all of the points in E11(1,6)
[8M]
(b) For E11(1,6) , consider the point G=(2,7) Compute the multiples of G from2G through 4G [8M]
4. (a) Explain in detail about Extended Euclid’s Algorithm.
(b) Using above algorithm find the multiplicative Inverse of 1234 mod 4321. [8+8]
5. (a) List requirements for a Hash Function.
(b) What basic arithmetical and logical functions are used in SHA-1? [6+10]
6. (a) What is R64 conversion?
(b) Why is R64 conversion useful for an e-mail application?
(c) Why is the segmentation and reassembly function in PGP needed? [4+6+6]
7. Write note on Encapsulating security payload. [16]
8. Write notes on
(a) Fire walls
(b) Trojan Horse Defense [8+8]
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