Introduction to Cryptography D334

Question 1

A business wants to use keys issued by a trusted third party to demonstrate to potential customers that it is a legitimate organization. Which key is used to sign the certificate issued to the business?

Answer 1

Private key of the root CA

Question 2

A business wants to use keys issued by a trusted third party to demonstrate it is legitimate organization to potential customers. Which key should the business send to potential customers to prove its identity?

Answer 2

Public key of the company

Question 3

What should an administrator use to import and export all items written using X.509 that are part of a chain of trust?

Answer 3

Public Key Cryptography Standard (PKCS) #12

Question 4

Which field displays the hash, or digest, of the certificate in an X.509 certificate?

Answer 4

Thumbprint

Question 5

Which certificate management process involves key recovery?

Answer 5

Issued

Question 6

Which task does a root CA perform before publishing its own certificate?

Answer 6

Signing it with its private key

Question 7

Which algorithm is used to generate the thumbprint of a certificate?

Answer 7

SHA-1

Question 8

Large volumes of plaintext need to be encrypted, and the encryption keys need to be securely distributed. Which approach should be used for encryption and distribution?

Answer 8

Encryption by using symmetric keys and distribute by using asymmetric keys

Question 9

What is the role of a key in asymmetric encryption and decryption?

Answer 9

A public key is used for encryption, and a private key is used for decryption.

Question 10

A security analyst is validating the integrity and authenticity of a date transaction. Which PKI component is being used?

Answer 10

Digital signature

Question 11

Which PKI component generates digital certificates?

Answer 11

Certificate authority (CA)

Question 12

What is the maximum length (in bits) of encryption keys used by the WEP protocol?

Answer 12

40

Question 13

What is a difference between WPA-Enterprise and WPA-Personal?

Answer 13

Support for an authentication server

Question 14

Which cipher is used with WEP?

Answer 14

RC4

Question 15

How does TKIP improve WPA over WEP?

Answer 15

Hashes the initialization vector and secret key

Question 16

An administrator has configured a virtual private network (VPN) connection utilizing IPsec tunnel mode with Encapsulating Security Payload (ESP) between the corporate office and a remote office. Where can the packets be inspected by intrusion detection systems (IDSs) and virus scanners?

Answer 16

At the headquarters and the offsite location

Question 17

Which default port must be open for the IPsec key exchange to be successful?

Answer 17

UDP 500

Question 18

Which protocol indicates the virtual private network (VPN) is using Authentication Header (AH)?

Answer 18

51

Question 19

Which cipher uses a grid to map letters into numeric values?

Answer 19

Bifid

Question 20

Which cipher uses a five-by-five matrix with nonrepeating characters?

Answer 20

Playfair

Question 21

What does a frequency analysis attack to break encryption involve?

Answer 21

Analyzing ciphertext to identify text variation and comparing the text to standard English characters.

Question 22

Which technique should a security analyst use to determine the key length in a Vigenere cipher?

Answer 22

Kasiski examination

Question 23

What defines a prime number?

Answer 23

Only has factors of itself and 1

Question 24

What is 29 and 12?

Answer 24

5

Question 25

Which type of cipher is ChaCha?

Answer 25

Stream

Question 26

What is the key size for RC4 with WEP?

Answer 26

40 bits

Question 27

Which symmetric encryption technique uses a 56-bit key size and a 64-bit block size?

Answer 27

DES

Question 28

Which wireless security standard uses a 128-bit RC4 stream cipher for encrypted communications?

Answer 28

WPA

Question 29

Employee B sends Employee A an encrypted message. What does Employee A use to decrypt the message from Employee B?

Answer 29

Employee A's private key

Question 30

What is an example of symmetric algorithm?

Answer 30

AES

Question 31

Which two components involved in performing encryption are known to the party that will perform decryption before symmetric encryption is applied? Choose 2.

Answer 31

Cryptographic algorithm & Cryptographic key

Question 32

Employee A created a secret key and wants to send it to Employee B without any coworkers being able to decrypt the message. Which key needs to encrypt the message?

Answer 32

Employee B's public key

Question 33

What happens to the trash of a file if it rehashed after the first character of the file is changed?

Answer 33

The entire hash is different

Question 34

What is the length (in bits) of an MD5 hash output?

Answer 34

128

Question 35

How many characters are used in an LM hash password?

Answer 35

14

Question 36

A Windows credential is identified as follows: user:FDA95FBABC199D22LLD3B435B51876KK:199DDFD4EF0E9CD9KMNC6FE771IL124B8:::. What is used to store this password?

Answer 36

NTLM

Question 37

What is a rainbow table?

Answer 37

Precompiled list of hash values

Question 38

Which mode encrypts each group with the same key, leaving each group independent of the others?

Answer 38

ECB

Question 39

Which mode of block encryption results in the same outcome for matching blocks of a plaintext message?

Answer 39

Electronic Code Book (ECB)

Question 40

How does CBC mode encryption function?

Answer 40

Uses an initialization vector (IV) to encrypt the first block, then uses the result of the encryption to encrypt the next block.

Question 41

Which encryption mode always produces the same result for the same plaintext?

Answer 41

ECB

Question 42

Which information protection method has an 80-bit key and operates on 64-bit data blocks?

Answer 42

Skipjack

Question 43

How many transformation rounds does AES use with a 192-bit key?

Answer 43

12

Question 44

How many transformation rounds does AES use with a 128-bit key?

Answer 44

10

Question 45

Which encryption algorithm did the National Institute of Standards and Technology (NIST) designate as a specification for the encryption of electronic information?

Answer 45

AES

Question 46

Which attack tries every combination of letters, numbers, and special characters?

Answer 46

Brute-force

Question 47

How does a dictionary attack break a cipher?

Answer 47

Takes a list of the most common words and tries each entry.

Question 48

A security analyst decrypted a data set with the same key that originally encrypted the data set. Which cryptographic operation did the analyst use?

Answer 48

Symmetric

Question 49

What should be used when large amounts of data need to be encrypted and decrypted for secure storage based on groupings of 128, 192, or 256 bits? 

Answer 49

Symmetric block

Question 50

Why is symmetric stream used to encrypt video when speed is a major concern?

Answer 50

It uses the same key to encrypt and decrypt large amounts of media.

Question 51

Why should an asymmetric public key be used to encrypt a symmetric key that is being sent to one person? 

Answer 51

It encrypts a small amount of information, which is decrypted with the corresponding private key.

Question 52

Which type of attacks are Diffie-Hellman methods vulnerable to? 

Answer 52

Man-in-the-middle

Question 53

Which mechanism mitigates a copy-and-paste attack when using AES? 

Answer 53

Output feedback (OFB) loop

Question 54

Which mechanism can be used to ensure perfect forward secrecy during key exchange when using symmetric encryption? 

Answer 54

ECDH

Question 55

Which encryption component ensures that the compromise of a long-term key prevents the compromise of any previous session keys? 

Answer 55

Forward secrecy

Question 56

What can XOR use as a pseudorandom number to create unique ciphertext?

Answer 56

Initialization vector

Question 57

How does cipher block chaining (CBC) create randomness in a second block after encrypting the first block with an initialization vector (IV)?

Answer 57

Uses the results of the IV to encrypt the next block

Question 58

How is information about Bitcoin transactions stored? 

Answer 58

Distributed peer-to-peer network

Question 59

What is one of the primary characteristics of a blockchain in the context of Bitcoin?

Answer 59

Adding blocks to a blockchain is computationally expensive.

Question 60

What is the length (in bits) of the private key used to sign transactions and associated with an individual wallet in the context of Bitcoin? 

Answer 60

256