Cryptography & Network Security

1. is the science and art of transforming messages to make them secure and immune to attacks

• Cryptography

• Cryptoanalysis

• either (a) or (b)

• neither (a) nor (b)

The is the original message before transformation

• ciphertext

• plaintext

• secret-text

• none of the above

3. The is the message after transformation

• ciphertext

• plaintext

• secret-text

• none of the above

4.A(n) algorithm transforms plaintext to ciphertext

• encryption

• decryption

• either (a) or (b)

• neither (a) nor (b)

A combination of an encryption algorithm and a decryption algorithm is called a _______________

• cipher

• secret

• key

• none of the above

In an asymmetric-key cipher, the sender uses the_ key

• private

• public

• either (a) or (b)

• neither (a) nor (b)

ciphers can be categorized into two broad categories: mono alphabetic and Poly alphabetic

• Substitution

• Transposition

• either (a) or (b)

• neither (a) nor (b)

DES uses a key generator to generate sixteen ____round keys

• 32-bit

• 48-bit

• 54-bit

• 42-bit

In brute force attack, on average half of all possible keys must be tried to achieve success.

• True

• False

What is 11 mod 7 and -11 mod 7?

• a) 4 and 5

• b) 4 and 4

• c) 5 and 3

• d) 4 and -4