Deck 12: Message Authentication Codes

Question 1

_________ encryption provides authentication among those who share the secret key.

A)Message
B)Asymmetric
C)Symmetric
D)Authenticated

Answer 1

C

Question 2

A brute-force attack on a MAC is easier than a brute-force attack on a hash function.

Answer 2

False

Question 3

Message authentication is a mechanism or service used to verify the integrity of a message.

Answer 3

True

Question 4

Message encryption by itself cannot provide a measure of authentication.

Question 5

The MAC does not provide a digital signature because both sender and receiver share the same key.

Question 6

If the calculated frame check sequence is equal to the incoming frame check sequence the message is considered authentic.

Question 7

Confidentiality can be provided by performing message encryption __________ the MAC algorithm.

A)before
B)before or after
C)after
D)during

Question 8

The straightforward use of public-key encryption provides confidentiality and authentication.

Question 9

One means of forming a MAC is to combine a cryptographic hash function in some fashion with a secret key.

Question 10

Message authentication may also verify sequencing and timeliness.

Question 11

The order in which the frame check sequence and encryption functions are performed is not critical for authentication.

Question 12

A __________ is an algorithm that requires the use of a secret key.

A)DAA
B)SHA
C)GCM
D)MAC

Question 13

An important characteristic of the MAC algorithm is that it needs to be reversible.

Question 14

To attack MD5,the attacker can choose any set of messages and work on these offline on a dedicated computing facility to find a collision.

Question 15

As with encryption algorithms and hash functions cryptanalytic attacks on MAC algorithms seek to exploit some property of the algorithm to perform some attack other than an exhaustive search.

Question 16

The __________ mode of operation is designed to be parallelizable so that it can provide high throughput with low cost and low latency.

A)DAA
B)CCM
C)GCM
D)CTR

Question 17

A recipient in possession of the secret key cannot generate an authentication code to verify the integrity of the message.

Question 18

Insertion of messages into the network from a fraudulent source is a __________ attack.

A)content modification
B)masquerade
C)source repudiation
D)sequence modification

Question 19

The security of any MAC function based on an embedded hash function depends in some way on the cryptographic strength of the underlying hash function.

Question 20

A CTR-based authenticated encryption approach is the most efficient mode of operation for high-speed packet networks.

Question 21

The essential elements of any pseudorandom number generator are a __________ and a deterministic algorithm for generating a stream of pseudorandom bits.

A)secret key
B)session key
C)seed value
D)stream encryption function

Question 22

Attacks on MACs can be grouped into two categories: brute-force attacks and __________ .

Question 23

The _________ attack is when the attacker is looking for two messages M and M1 that produce the same hash: HM)= HM1)

A)birthday
B)chaining
C)MAC
D)hash

Question 24

The GCM mode makes use of two functions: __________,which is a keyed hash function,and GCTR.

A)CTR
B)HMAC
C)GHASH
D)CCM

Question 25

Any modification to a sequence of messages between parties,including insertion,deletion,and reordering is a __________ attack.

Question 26

An alternative authentication technique involves the use of a secret key to generate a small fixed size block of data known as a __________ or MAC that is appended to the message.

Question 27

The types of functions that may be used to produce an authenticator are grouped into three classes: hash function,message authentication code,and ___________ .

Question 28

The MAC function is a __________ function.

A)one-to-many
B)many-to-one
C)one-to-one
D)one-to-two

Question 29

When an entire message is encrypted for confidentiality using either symmetric or asymmetric encryption the security of the scheme generally depends on the __________ of the key.

Question 30

__________ assures that data received are exactly as sent and that the purposed identity of the sender is valid.

Question 31

The key algorithmic ingredients of _________ are the AES encryption algorithm,the CTR mode of operation,and the CMAC authentication algorithm.

A)DAA
B)GCM
C)CCM
D)CMA

Question 32

The __________ algorithm can be defined as using the cipher block chaining mode of operation of DES with an initialization vector of zero.

Question 33

"Release of message contents to any person or process not possessing the appropriate cryptographic key" is a __________ attack.

A)content modification
B)source repudiation
C)disclosure
D)sequence modification

Question 34

The approach taken by the Transport Layer Security protocol and the Wireless Transport Layer Security Protocol involve invoking HMAC _________ for each block of output wi.

A)zero times
B)twice
C)three times
D)once

Question 35

A __________ takes a variable length message and a secret key as input and produces an authentication code.

Question 36

Discovery of the pattern of traffic between parties is a __________ attack.

Question 37

Two MACs that are based on the use of a block cipher mode of operation are Data Authentication Algorithm and __________ .

A)GMAC
B)DMAC
C)TMAC
D)CMAC

Question 38

With _________ authentication an opponent would have difficulty generating ciphertext that when decrypted would have valid error control bits.

A)checksum
B)CMAC
C)cipher block chaining
D)internal error control

Question 39

The appeal of __________ is that its designers have been able to prove an exact relationship between the strength of the embedded hash function and the strength of this form of authentication.

A)MAC
B)HMAC
C)GMAC
D)CMAC

Question 40

One approach to constructing a MAC is to use a symmetric block cipher in such a way that it produces a __________ output for a variable length input.

Question 41

HMAC is a widely used standardized _________ function and is implemented in many protocols and applications.

Question 42

NIST SP 800-90,IEEE 802.11i,and TLS/WTLS are three ____________ based on HMAC.

Question 43

___________ is a term used to describe encryption systems that simultaneously protect confidentiality and authenticity of communications.

Question 44

The __________ mode of operation was standardized by NIST specifically to support the security requirements of IEEE 802.1 WiFi wireless local area networks but can be used in any networking application requiring authenticated encryption.

Question 45

The HtE approach is used in the __________ protocol to protect WiFi networks.