Ch 2 Crytopgraphic Tools Quiz
The most important symmetric algorithms, all of which are block ciphers, are the DES, triple DES, and the __________.
AES
Cryptanalytic attacks try every possible key on a piece of ciphertext until an intelligible translation into plaintext is obtained.
False
Like the MAC, a hash function also takes a secret key as input
False
Public-key algorithms are based on simple operations on bit patterns
False
The advantage of a stream cipher is that you can reuse keys
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
False
Triple DES takes a plaintext block of 64 bits and a key of 56 bits to produce a ciphertext block of 64 bits
False
A message authentication code is a small block of data generated by a secret key and appended to a message
True
An important element in many computer security services and applications is the use of cryptographic algorithms
True
The secret key is input to the encryption algorithm
True
The strength of a hash function against brute-force attacks depends solely on the length of the hash code produced by the algorithm
True
Two of the most important applications of public-key encryption are digital signatures and key management.
True
A __________ is to try every possible key on a piece of ciphertext until an intelligible translation into plaintext is obtained.
brute force attack
__________ is the scrambled message produced as output
ciphertext
Transmitted data stored locally are referred to as __________ .
data at rest
The __________ is the encryption algorithm run in reverse
decryption algorithm
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.
digital signature
The original message or data that is fed into the algorithm is
Plaintext
__________ is a block cipher in which the plaintext and ciphertext are integers between 0 and n-1 for some n.
RSA
Modes of operation are the alternative techniques that have been developed to increase the security of symmetric block encryption for large sequences of data
True
Public-key cryptography is asymmetric
True
Some form of protocol is needed for public-key distribution
True
Symmetric encryption is used primarily to provide confidentiality
True
On average, __________ of all possible keys must be tried in order to achieve success with a brute-force attack.
half
The purpose of a __________ is to produce a "fingerprint" of a file, message, or other block of data.
hash function
Combined one byte at a time with the plaintext stream using the XOR operation, a __________ is the output of the pseudorandom bit generator.
keystream
__________ is a procedure that allows communicating parties to verify that received or stored messages are authentic.
message authentication
Digital signatures and key management are the two most important applications of __________ encryption.
public key
A _________ protects against an attack in which one party generates a message for another party to sign.
strong hash function
Also referred to as single-key encryption, the universal technique for providing confidentiality for transmitted or stored data is
symmetric encryption
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 __________ .
use longer keys
10. In July 1998 the ____EEF______ announced that it had broken a DES encryption using a special purpose "DES cracker" machine.
.
3. The __decryption ________ algorithm takes the ciphertext and the secret key and produces the original plaintext.
.
A ____Triple DES______ processes the plaintext input in fixed-size blocks and produces a block of ciphertext of equal size for each plaintext block.
.
A ____back end appliance_____ 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.
.
A ____pseudorandom______ stream is one that is unpredictable without knowledge of the input key and which has an apparently random character.
.
A ___stream cipher___ processes the input elements continuously, producing output one element at a time.
.
A __cryptanalysis________ attack exploits the characteristics of the algorithm to attempt to deduce a specific plaintext or to deduce the key being used.
.
Public-key encryption was first publicly proposed by _____Diffie & Hellman_____ in 1976.
.
The ____public & private key______ is a pair of keys that have been selected so that if one is used for encryption, the other is used for decryption.
.
The purpose of the _____diffie-hellman key agreement_____ 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.
.
The simplest approach to multiple block encryption is known as _____electronic codebook_____ mode, in which plaintext is handled b bits at a time and each block of plaintext is encrypted using the same key.
.
The two criteria used to validate that a sequence of numbers is random are independence and ____uniform distribution_____ .
.
There are two general approaches to attacking a symmetric encryption scheme: cryptanalytic attacks and ___brute force attacks_______ attacks.
.
____library based tape encryption______ is provided by means of a co-processor board embedded in the tape drive and tape library hardware.
.
