Deck 2: Cryptographic Tools

Question 1

Cryptanalytic attacks try every possible key on a piece of ciphertextuntil an intelligible translation into plaintext is obtained.

Answer 1

False

Question 2

Some form of protocol is needed for public-key distribution.

Answer 2

True

Question 3

The __________ is the encryption algorithm run in reverse.

A) decryption algorithm
B) plaintext
C) ciphertext
D) encryption algorithm

Answer 3

A

Question 4

__________ is the scrambled message produced as output.

A) Plaintext
B) Ciphertext
C) Secret key
D) Cryptanalysis

Question 5

Like the MAC, a hash function also takes a secret key as input.

Question 6

The strength of a hash function against brute-force attacks dependssolely on the length of the hash code produced by the algorithm.

Question 7

Modes of operation are the alternative techniques that have beendeveloped to increase the security of symmetric block encryption for large sequences of data.

Question 8

T F 4. The secret key is input to the encryption algorithm.

Question 9

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

A) one-fourth
B) half
C) two-thirds
D) three-fourths

Question 10

Public-key algorithms are based on simple operations on bit patterns.

Question 11

An important element in many computer security services andapplications is the use of cryptographic algorithms.

Question 12

The most important symmetric algorithms, all of which are block ciphers, are the DES, triple DES, and the __________.

A) SHA
B) RSA
C) AES
D) DSS

Question 13

The original message or data that is fed into the algorithm is __________.

A) encryption algorithm
B) secret key
C) decryption algorithm
D) plaintext

Question 14

T F 13. The purpose of the DSS algorithm is to enable two users to securelyreach agreement about a shared secret that can be used as a secret keyfor subsequent symmetric encryption of messages.

Question 15

Public-key cryptography is asymmetric.

Question 16

A message authentication code is a small block of data generated by asecret key and appended to a message.

Question 17

Symmetric encryption is used primarily to provide confidentiality.

Question 18

The advantage of a stream cipher is that you can reuse keys.

Question 19

Triple DES takes a plaintext block of 64 bits and a key of 56 bits toproduce a ciphertext block of 64 bits.

Question 20

Two of the most important applications of public-key encryption aredigital signatures and key management.

Question 21

There are two general approaches to attacking a symmetric encryption scheme:cryptanalytic attacks and __________ attacks.

Question 22

The __________ algorithm takes the ciphertext and the secret key and producesthe original plaintext.

Question 23

Digital signatures and key management are the two most important applications of __________ encryption.

A) private-key
B) public-key
C) preimage resistant
D) advanced

Question 24

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 __________ .

A) use longer keys
B) use shorter keys
C) use more keys
D) use less keys

Question 25

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.

A) digital signature
B) keystream
C) one way hash function
D) secret key

Question 26

In July 1998 the __________ announced that it had broken a DES encryption using a special purpose "DES cracker" machine.

Question 27

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

A) secret key
B) digital signature
C) keystream
D) hash function

Question 28

Transmitted data stored locally are referred to as __________ .

A) ciphertext
B) DES
C) data at rest
D) ECC

Question 29

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

A) Cryptanalysis
B) Decryption
C) Message authentication
D) Collision resistance

Question 30

Combined one byte at a time with the plaintext stream using the XOR operation, a __________ is the output of the pseudorandom bit generator.

A) keystream
B) digital signature
C) secure hash
D) message authentication code

Question 31

A __________ is to try every possible key on a piece of ciphertext until an intelligible translation into plaintext is obtained.

A) mode of operation
B) hash function
C) cryptanalysis
D) brute-force attack

Question 32

A __________ processes the plaintext input in fixed-size blocks and produces a block of ciphertext of equal size for each plaintext block.

Question 33

A _________ is a hardware device that sits between servers and storage systems and encrypts all data going from the server to the storage system and decrypts data going in the opposite direction.

Question 34

A _________ protects against an attack in which one party generates a message for another party to sign.

A) data authenticator
B) strong hash function
C) weak hash function
D) digital signature

Question 35

Public-key encryption was first publicly proposed by __________ in 1976.

Question 36

A __________ processes the input elements continuously, producing output one element at a time.

Question 37

The two criteria used to validate that a sequence of numbers is random are independence and _________ .

Question 38

A __________ attack exploits the characteristics of the algorithm to attempt to deduce a specific plaintext or to deduce the key being used.

Question 39

Also referred to as single-key encryption, the universal technique for providing confidentiality for transmitted or stored data is __________ .

Question 40

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

A) DSS
B) RSA
C) SHA
D) AES

Question 41

The __________ is a pair of keys that have been selected so that if one is used for encryption, the other is used for decryption.

Question 42

__________ is provided by means of a co-processor board embedded in the tape drive and tape library hardware.

Question 43

The simplest approach to multiple block encryption is known as __________ mode, in which plaintext is handled b bits at a time and each block of plaintext is encrypted using the same key.

Question 44

A __________ stream is one that is unpredictable without knowledge of the input key and which has an apparently random character.

Question 45

The purpose of the __________ algorithm is to enable two users to securely reach agreement about a shared secret that can be used as a secret key for subsequent symmetric encryption of messages.