Tech 3498 Ch2

digital signature

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. Group of answer choices digital signature keystream one way hash secret key

brute-force attack

A __________ is to try every possible key on a piece of ciphertext until an intelligible translation into plaintext is obtained. Group of answer choices mode of operation hash function cryptanalysis brute-force attack

True

A message authentication code is a small block of data generated by a secret key and appended to a message. Group of answer choices True False

False

Cryptanalytic attacks try every possible key on a piece of ciphertext until an intelligible translation into plaintext is obtained. Group of answer choices True False

public-key

Digital signatures and key management are the two most important applications of __________ encryption. Group of answer choices private-key public-key preimage resistant advanced

use longer keys

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 __________ . Group of answer choices use longer keys use shorter keys use more keys use less keys

False

Like the MAC, a hash function also takes a secret key as input. Group of answer choices True False

True

Modes of operation are the alternative techniques that have been developed to increase the security of symmetric block encryption for large sequences of data. Group of answer choices True False

half

On average, __________ of all possible keys must be tried in order to achieve success with a brute-force attack. Group of answer choices one-fourth half two-thirds three-fourths

decryption algorithm

The __________ is the encryption algorithm run in reverse. Group of answer choices decryption algorithm plaintext ciphertext encryption algorithm

False

The advantage of a stream cipher is that you can reuse keys. Group of answer choices True False

AES

The most important symmetric algorithms, all of which are block ciphers, are the DES, triple DES, and the __________. Group of answer choices SHA RSA AES DSS

plaintext

The original message or data that is fed into the algorithm is __________. Group of answer choices encryption algorithm secret key decryption algorithm plaintext

hash function

The purpose of a __________ is to produce a "fingerprint" of a file, message, or other block of data. Group of answer choices secret key digital signature keystream hash function

False

The purpose of the DSS 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. Group of answer choices True False

True

The secret key is input to the encryption algorithm. Group of answer choices True False

True

The strength of a hash function against brute-force attacks depends solely on the length of the hash code produced by the algorithm. Group of answer choices True False

data at rest

Transmitted data stored locally are referred to as __________ . Group of answer choices ciphertext DES data at rest ECC

False

Triple DES takes a plaintext block of 64 bits and a key of 56 bits to produce a ciphertext block of 64 bits. Group of answer choices True False

RSA

__________ is a block cipher in which the plaintext and ciphertext are integers between 0 and n-1 for some n. Group of answer choices DSS RSA SHA AES

Message authentication

__________ is a procedure that allows communicating parties to verify that received or stored messages are authentic. Group of answer choices Cryptanalysis Decryption Message authentication Collision resistance

Ciphertext

__________ is the scrambled message produced as output. Group of answer choices Plaintext Ciphertext Secret key Cryptanalysis

True

An important element in many computer security services and applications is the use of cryptographic algorithms. Group of answer choices True False

keystream

Combined one byte at a time with the plaintext stream using the XOR operation, a __________ is the output of the pseudorandom bit generator. Group of answer choices keystream digital signature secure hash message authentication code

False

Public-key algorithms are based on simple operations on bit patterns. Group of answer choices True False

True

Public-key cryptography is asymmetric. Group of answer choices True False

True

Some form of protocol is needed for public-key distribution. Group of answer choices True False

True

Symmetric encryption is used primarily to provide confidentiality. Group of answer choices True False

True

Two of the most important applications of public-key encryption are digital signatures and key management. Group of answer choices True False

strong hash function

A _________ protects against an attack in which one party generates a message for another party to sign. Group of answer choices data authenticator strong hash function weak hash function digital signature