Network security:

1. Hash function is used for ____.

a) Check integrity of data transfer

b) Checking non-repudiation

c) Bothe (a) and (b)

d) None of the options

2. DES use __ bit block and __ bit key size.

a) 64, 56

b) 65, 54

c) 64, 64

d) 56, 64

3. What is the advantage of symmetric key encryption over public key encryption?

a) Provides integrity and authentication

b) Uses less number of keys in a group communication scenario

c) Can be implemented in software

d) Faster than public key

4. In a three-way handshake key exchange, the following is true:

a) The server authenticates the client, but not vice versa.

b) The client authenticates the server, but not vice versa.

c) The client and the server both authenticated each other.

d) The client and the server do not authenticate each other.

5. What is the most significant feature of the Diffie-Hellman exchange?

a) East key exchange.

b) Easy to implement.

c) Key exchange among a group of nodes.

d) Keys are never exchanged, but are generated.

6. You can get back a message M with the following procedure.

a) Encrypt M with Alices public key and decrypt it with Alices private key.

b) Encrypt M with Bobs private key and decrypt it with Bobs public key.

c) Encrypt M with Bobs public key and decrypt it with Alices private key.

d) Both (a) and (b).

e) Either (b) or (c).

7. One of the advantages of stream ciphers over block ciphers is

a) It is much more secure.

b) The standards are well-defined.

c) Errors do not propagate.

d) It is more scalable.

8. A digital signature is produced by the following procedure:

a) Hash the message M and encrypt it with the senders public key.

b) Hash the message M and encrypt it with the senders private key.

c) Hash the message M and encrypt it with the recipients public key.

d) Hash the message M and encrypt it with the recipients private key.

9. A prime concern with DES has been its vulnerability to brute-force attack because of its _____.

a) Short data block length.

b) Relatively easy permutation operation.

c) Relatively short key length.

d) Relatively less repetition steps.

10. Indicate what may be true for pseudorandom numbers.

a) They appear random but repeatable.

b) Generated from a fixed random seed.

c) Generate same sequence of numbers with same seed value.

d) All of the options.