Cryptography Model Question Solution | Crypto bsc csit solution | csit 5th sem

Cryptography Model Question Solution | Crypto bsc csit solution | csit 5th sem

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Attempt any TWO questions. [2×10=20]

1. Mention the families SHA-2? Describe how 160-bit of hash value is generated by taking

an input message of variable size using SHA-1? [2+8]

2. Discuss how encryption and decryption is done using RSA? In a RSA system, a user

Named Ram has chosen the primes 5 and 7 to create a key pair. The public key is

(eRam,n) and the private key is (dRam, n). Compute the private and public key pairs.

Suppose another user Sita knows public key of Ram and want to send the plaintext “hi”

to Ram using RSA Scheme. Show how Sita has encrypted the plaintext and Ram has

decrypted the ciphertext. [5+5]

3. Describe the working principle of Fiestel Cipher Structure.Give the encryption and

decryption procedure for 2-DES and 3-DES. Find the multiplicative inverse of 7 in Z11

using Extended Euclidean Algorithm.

[4+2+4]

Section B

Short Answer Questions

Attempt any EIGHT questions. [8×5=40]

4. Define authentication system. How challenge response systems can be used as

authentication approach? [1+4]

5. Define SSL. How SSL Record Protocol provides security in Secure Socket Layer

Protocol? [1+4]

6. Decrypt the message “CMAL” using the Hill cipher with the key

   Show your calculations and the result.

7. Divide 5x2+ 4x + 6 by 2x + 1 over GF(7). [5]

8. Differentiate between virus, worm and trojan horse. [5]

9. Describe the purpose of PKI trust model? List any four types of firewall. [3 + 2]

10. What is digital signature? How DSS Approach is used to generate digital signature?

[1+4]

11. Define Euler totient function. Find out whether 3 is primitive root of 7? [1 + 4]

12. Write Short Notes On (Any TWO) [2.5 + 2.5]

a. Vernam Cipher

b. Kerberos Protocol

c. Intrusion Detection System