Deck 21: Public-Key Cryptography and Message Authentication

Question 1

The Diffie-Hellman algorithm depends for its effectiveness on the
difficulty of computing discrete logarithms.

Answer 1

True

Question 2

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

Answer 2

True

Question 3

HMAC can be proven secure provided that the embedded hash function
has some reasonable cryptographic strengths.

Answer 3

True

Question 4

The key exchange protocol is vulnerable to a man-in-the-middle
attack because it does not authenticate the participants.

Question 5

Timing attacks are only applicable to RSA.

Question 6

RSA is a block cipher in which the plaintext and ciphertext are integers
between 0 and n - 1 for some n.

Question 7

Issued as RFC 2104,__________ has been chosen as the mandatory-to-implement MAC for IP Security.

A)RSA
B)SHA-3
C)DSS
D)HMAC

Question 8

A hash function such as SHA-1 was not designed for use as a MAC
and cannot be used directly for that purpose because it does not rely on a secret key.

Question 9

SHA-1 is considered to be very secure.

Question 10

In 2005,NIST announced the intention to phase out approval of _______ and move to a reliance on the other SHA versions by 2010.

A)SHA-1
B)SHA-512
C)SHA-256
D)SHA-2

Question 11

SHA is perhaps the most widely used family of hash functions.

Question 12

The _________ scheme has reigned supreme as the most widely accepted and implemented approach to public-key encryption.

A)SHA-1
B)HMAC
C)MD5
D)RSA

Question 13

A ________ attack involves trying all possible private keys.

A)mathematical
B)timing
C)brute-force
D)chosen ciphertext

Question 14

Cryptographic hash functions generally execute faster in software
than conventional encryption algorithms such as DES.

Question 15

Unlike RSA,DSS cannot be used for encryption or key exchange.

Question 16

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

Question 17

The operations performed during a round consist of circular
shifts,and primitive Boolean functions based on DSS,MD5,SHA,and RSA.

Question 18

SHA-2 shares the same structure and mathematical operations as its
predecessors and this is a cause for concern.

Question 19

SHA-3 algorithms must be designed to resist any potentially
successful attack on SHA-2 functions.

Question 20

SHA-1 produces a hash value of __________ bits.

A)256
B)160
C)384
D)180

Question 21

The purpose of the __________ algorithm is to enable two users to exchange a secret key securely that can then be used for subsequent encryption of messages.

Question 22

Although the _________ attack is a serious threat,there are simple countermeasures that can be used such as constant time calcs,random delays or blinding computations.

A)timing
B)chosen ciphertext
C)mathematical
D)none of the above

Question 23

__________ are alarming for two reasons: they come from a completely unexpected direction and they are a ciphertext-only attack.

Question 24

The Secure Hash Algorithm (SHA)was developed by the _________ and published as a federal information processing standard (FIPS 180)in 1993.

Question 25

_________ attacks have several approaches,all equivalent in effort to factoring the product of two primes.

A)Mathematical
B)Brute-force
C)Chosen ciphertext
D)Timing

Question 26

Four possible approaches to attacking the RSA algorithm are: brute force,timing attacks,_________ attacks,and chosen ciphertext attacks.

Question 27

The evaluation criteria for the new hash function are: security,_______,and algorithm and implementation characteristics.

Question 28

______ has been issued as RFC 2014,has been chosen as the mandatory-to-implement MAC for IP Security,and is used in other Internet protocols,such as Transport Layer Security.

Question 29

The principal attraction of __________ compared to RSA is that it appears to offer equal security for a far smaller bit size,thereby reducing processing overhead.

A)ECC
B)MD5
C)Diffie-Hellman
D)none of the above

Question 30

One of the simplest hash functions is the ________ of every block.

Question 31

___________ was the first published public-key algorithm.

A)NIST
B)Diffie-Hellman
C)RC4
D)RSA

Question 32

A __________ type of attack exploits properties of the RSA algorithm.

A)timing
B)brute-force
C)chosen ciphertext
D)mathematical

Question 33

The _________ attack exploits the common use of a modular exponentiation algorithm in RSA encryption and decryption,but can be adapted to work with any implementation that does not run in fixed time.

A)mathematical
B)timing
C)chosen ciphertext
D)brute-force

Question 34

NIST has published FIPS PUB 186,which is known as the ___________.

Question 35

The __________ uses an algorithm that is designed to provide only the digital signature function and cannot be used for encryption or key exchange.

A)ECC
B)RSA
C)DSS
D)XOR

Question 36

The National Institute of Standards and Technology has published Federal Information Processing Standard FIPS PUB 186,known as the __________.

A)XOR
B)MD5
C)MAC
D)DSS

Question 37

One of the first public-key schemes,_______,was developed in 1977 by Ron Rivest,Adi Shamir,and Len Adleman.

Question 38

The DSS makes use of the _________ and presents a new digital signature technique,the Digital Signature Algorithm (DSA).

A)HMAC
B)XOR
C)RSA
D)SHA-1

Question 39

Versions of SHA,with hash value lengths of 256,384,and 512 bits,(SHA-256,SHA-384,and SHA 512)are collectively known as _________.

Question 40

_________ are analogous to a burglar guessing a safe combination by observing how long it takes to turn the dial from number to number.

A)Digital standards
B)Mathematical attacks
C)Ciphers
D)Timing attacks

Question 41

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

Question 42

The purpose of the algorithm is to enable two users to exchange a __________ securely that can then be used for subsequent encryption of messages.

Question 43

If speed is a concern,it is fully acceptable to use _________ rather than SHA as the embedded hash function for HMAC.

Question 44

"Must support hash value lengths of 224,256,384,and 512 bits" and "algorithm must process small blocks at a time instead of requiring the entire message to be buffered in memory before processing it" are requirements for ________.

Question 45

Perhaps the most widely used public-key algorithms are _________ and Diffie-Hellman.