Cryptography, Encryption, Hashes

Question 1

Symmetric encryption is used primarily to provide confidentiality.(T/F)

Answer 1

True

Question 2

Two of the most important applications of public-key encryption are digital signatures and key management.(T/F)

Answer 2

True

Question 3

The secret key is one of the inputs to a symmetric-key encryption algorithm.(T/F)

Answer 3

True

Question 4

The strength of a hash function against brute-force attacks depends on the length of the hash code produced by the algorithm.(T/F)

Answer 4

True

Question 5

Public-key algorithms are based on simple operations on bit patterns. (T/F)

Answer 5

False

Question 6

On average, ________ of all possible keys must be tried in order to achieve success with a brute-force attack.

Answer 6

half

Question 7

If the only form of attack that could be made on an encryption algorithm is brute-force, then the way to counter such attacks would be to ________ .

Answer 7

use longer keys

Question 8

________ is a procedure that allows communicating parties to verify that received or stored messages are authentic.

Answer 8

Message authentication

Question 9

The purpose of a ________ is to produce a ?fingerprint? of a file, message, or other block of data.

Answer 9

hash function

Question 10

A _________ is created by using a secure hash function to generate a hash value for a message and then encrypting the hash code with a private key.

Answer 10

digital signature

Question 11

Symmetric encryption is also referred to as secret-key or single-key encryption.(T/F)

Answer 11

True

Question 12

The ciphertext-only attack is the easiest to defend against.(T/F)

Answer 12

True

Question 13

A brute-force approach involves trying every possible key until an intelligible translation of the ciphertext into plaintext is obtained.(T/F)

Answer 13

True

Question 14

AES uses a Feistel structure.(T/F)

Answer 14

False

Question 15

Each block of 64 plaintext bits is encoded independently using the same key? is a description of the CBC mode of operation.(T/F)

Answer 15

False

Question 16

Timing attacks are only applicable to RSA.(T/F)

Answer 16

False

Question 17

Using PKCS (public-key cryptography standard), when RSA encrypts the same message twice, different ciphertexts will be produced.(T/F)

Answer 17

True

Question 18

The Diffie-Hellman algorithm depends for its effectiveness on the difficulty of computing discrete logarithms.(T/F)

Answer 18

True

Question 19

A key exchange protocol is vulnerable to a man-in-the-middle attack if it does not authenticate the participants.(T/F)

Answer 19

True

Question 20

Just like RSA can be used for signature as well as encryption, Digital Signature Standard can also be used for encryption.(T/F)

Answer 20

False

Question 21

In general, public key based encryption is much slower than symmetric key based encryption. (T/F)

Answer 21

True

Question 22

________ is the original message or data that is fed into the encryption process as input.

Answer 22

Plaintext

Question 23

Which of the following would allow an attack that to know the (plaintext of) current message must be the same as one previously transmitted because their ciphtertexts are the same?

Answer 23

ECB

Question 24

________ is a term that refers to the means of delivering a key to two parties that wish to exchange data without allowing others to see the key.

Answer 24

Key distribution technique

Question 25

Which of the following feature can only be provided by public-key cryptography?

Answer 25

Non-repudiation

Question 26

Cryptographic systems are generically classified by _______.

Answer 26

A. the type of operations used for transforming plaintext to ciphertext

B. the number of keys used

C. the way in which the plaintext is processed

Question 27

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

Answer 27

Mathematical

Question 28

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

Answer 28

Timing attacks

Question 29

_________ was the first published public-key algorithm.

Answer 29

Diffie-Hellman

Question 30

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.

Answer 30

ECC

Question 31

SHA is perhaps the most widely used family of hash functions.(T/F)

Answer 31

True

Question 32

SHA-1 is considered to be very secure.(T/F)

Answer 32

False

Question 33

HMAC can be proven secure provided that the embedded hash function has some reasonable cryptographic strengths.(T/F)

Answer 33

True

Question 34

The additive constant numbers used in SHA-512 are random-looking and are hardcoded in the algorithm.(T/F)

Answer 34

True

Question 35

The strong collision resistance property subsumes the weak collision resistance property.(T/F)

Answer 35

True

Question 36

Cryptographic hash functions generally execute faster in software than conventional encryption algorithms such as DES and AES.(T/F)

Answer 36

True

Question 37

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.(T/F)

Answer 37

True

Question 38

It is a good idea to use sequentially increasing numbers as challenges in security protocols.(T/F)

Answer 38

False

Question 39

Assuming that Alice and Bob have each other?s public key. In order to establish a shared session key, Alice just needs to generate a random k, encrypt k using Bob?s public key, and send the encrypted k to Bob and then Bob will know he has a key shared with Alice. (T/F)

Answer 39

False

Question 40

SHA-1 produces a hash value of _______ bits.

Answer 40

160

Question 41

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

Answer 41

SHA-1