ESAT Forouzan - Chapter 30: Message Security, User Authentication and Key Management

Question 1

If user A wants to send an encrypted message to user B, the Plaintext is encrypted with the public key of _______.
a. User A
b. User B
c. The network
d. a or b

Answer 1

b. User B

Question 2

When symmetric-key encryption is combined with private-key encryption, the _______ key is encrypted with the public key.
a. Private
b. Public
c. Symmetric
d. Skeleton

Answer 2

c. Symmetric

Question 3

In the digital signature technique, the sender of the message uses _______ to create ciphertext.
a. His or her own symmetric key
b. His or her own private key
c. His or her public key
d. The receiver’s private key

Answer 3

b. His or her own private key

Question 4

In the digital signature technique, the receiver of the message uses _______ to create plaintext.
a. His or her own symmetric key
b. His or her own private key
c. His or her own public key
d. The sender’s public key

Answer 4

d. The sender’s public key

Question 5

A _______ is a trusted third party that solves the problem of symmetric-key distribution.
a. CA
b. KDC
c. TLS
d. Firewall

Answer 5

b. KDC

Question 6

A _______ certifies the bonding between a public key and its owner.
a. CA
b. KDC
c. TLS
d. Firewall

Answer 6

a. CA

Question 7

In a _______ attack, a message captured by an intruder is illegally sent a second time.
a. Return
b. Man-in-the-middle
c. Bucket brigade
d. Replay

Answer 7

d. Replay

Question 8

A _______ is a large number used only once that helps distinguish a fresh authentication request from a repeated one.
a. Ticket
b. Nonce
c. Realm
d. Public key

Answer 8

b. Nonce

Question 9

In an authentication using symmetric keys, if 10 people need to communicate, we need _______ keys.
a. 10
b. 20
c. 45
d. 90

Answer 9

c. 45

Question 10

In the _______ protocol, the symmetric key is K = Gxy mod N, where G and N are public numbers.
a. Diffie-Hellman
b. Needham-Schroeder
c. Otway Rees
d. Kerberos

Answer 10

a. Diffie-Hellman

Question 11

In a ________ attack, an intruder comes between two communicating parties, intercepting and replying to their messages.
a. Return
b. Man-in-the-Middle
c. Bucket-in-the-Middle
d. Replay

Answer 11

b. Man-in-the-Middle

Question 12

A _______ is a trusted third party that establishes a symmetric key between two parties who wish to communicate.
a. KDC
b. CA
c. PKI
d. TGS

Answer 12

a. KDC

Question 13

In the _______ protocol, a nonce is decremented by 1 so that an intruder cannot send the exact same message a second time.
a. Diffie-Hellman
b. Needham-Schroeder
c. Otway Rees
d. Kerberos

Answer 13

b. Needham-Schroeder

Question 14

_______ is an authentication protocol that needs an authentication server and a ticket-granting server.
a. Diffie-Hellman
b. Needham-Schroeder
c. Otway Rees
d. Kerberos

Answer 14

d. Kerberos

Question 15

The _______ is the KDC in the Kerberos protocol.
a. AS
b. TGS
c. Real server
d. Data server

Answer 15

a. AS

Question 16

The _______ issues tickets for the real server.
a. AS
b. TGS
c. Real server
d. Data server

Answer 16

a. AS

Question 17

In _______-key cryptography, everyone has access to all the public keys.
a. Private
b. Symmetric
c. Public
d. Certified

Answer 17

b. Symmetric

Question 18

A protocol called _______ describes the certificate issued by a CA in a structural way.
a. X.509
b. CA level 1
c. KDC
d. Kerberos

Answer 18

a. X.509

Question 19

Windows 2000 uses an authentication protocol called ________.
a. Diffie-Hellman
b. Needham-Schroeder
c. Otway Rees
d. Kerberos

Answer 19

d. Kerberos