Quiz 8 - Hashes & Security Protocols (ch21, 23)

Question 1

If the length of hash is 128 bits, then how many messages does an attacker need to search in order to find two that share the same hash?
A. 128
B. 2^127
C. 2^128
D. 2^64

Answer 1

D

Question 2

It’s much harder to launch successful collision attacks on HMAC because of secret key.

Answer 2

True

Question 3

Security depends on the cryptographic strength of the underlying hash function.

Answer 3

True

Question 4

The one-way hash function is important not only in message authentication but also in digital signatures.

Answer 4

False

Question 5

SHA processes the input one block at a time but each block goes through the same processing.

Answer 5

True

Question 6

HMAC is secure provided that the embedded hash function has good cryptographic strengths such as one-way and collision resistant.

Answer 6

True

Question 7

The challenge values used in an authentication protocol can be repeatedly used in multiple sessions.

Answer 7

False

Question 8

The authentication messages can be captured and replayed by an adversary.

Answer 8

True

Question 9

Authentication can be one-way, e.g., only authenticating Alice to Bob.

Answer 9

True

Question 10

A reflection attack is a form of man-in-the-middle attack.

Answer 10

True

Question 11

To defeat a reflection attack, we can use an odd number as challenge from the initiator and even number from the responder.

Answer 11

True

Question 12

We can use signing with public keys to achieve mutual authentication.

Answer 12

True

Question 13

A session key should be a secret and unique to the session.

Answer 13

True

Question 14

Authentication should be accomplished before key exchange.

Answer 14

True

Question 15

A key benefit of using KDC is for scalability.

Answer 15

True

Question 16

In order for Bob to verify Alice’s public key, the certificate authority must be on-line.

Answer 16

False

Question 17

Signing the message exchanges in Diffie-Hellman eliminates the main-in-the-middle attack.

Answer 17

True

Question 18

Kerberos provides authentication and access control.

Answer 18

True

Question 19

Kerberos also distributes session keys.

Answer 19

True

Question 20

To avoid over-exposure of a user’s master key, Kerberos uses a per-day key and a ticket-granting-ticket.

Answer 20

True

Question 21

The authenticators used in requests to KDC and application servers can be omitted.

Answer 21

False

Question 22

Access to any network resource requires a ticket issued by the KDC.

Answer 22

True