Deck 3: Cryptography

Question 1

A DES key is 40 bits long.

Answer 1

False

Question 2

Which of the following statements accurately describes RC4?

A) RC4 is very slow.
B) RC4 uses a large amount of RAM.
C) RC4 can use a broad range of key lengths.
D) All of the above

Answer 2

C

Question 3

In codes, code symbols may represent ________.

A) complete words
B) complete phrases
C) individual letters
D) All of the above

Answer 3

D

Question 4

When two parties communicate with each other using symmetric key encryption, how many keys are used in total to encrypt and decrypt?

A) 1
B) 2
C) 4
D) 8

Question 5

________ is the use of mathematical operations to protect messages travelling between parties or stored on a computer.

A) Cryptography
B) Encryption
C) Authentication
D) Confidentiality

Question 6

A DES key is ________ bits long.

A) 40
B) 56
C) 100
D) 128

Question 7

The best way to thwart exhaustive searches by cryptanalysts is ________.

A) to use codes
B) to make the key very long
C) randomize the key thoroughly
D) All of the above

Question 8

________ ciphers leave letters in their original positions.

A) Transposition
B) Substitution
C) Both A and B
D) Neither A nor B

Question 9

Which of the following is transmitted across a network?

A) The plaintext
B) The ciphertext
C) Both A and B
D) Neither A nor B

Question 10

If a key is 43 bits long, how much longer will it take to crack it by exhaustive search if it is extended to 50 bits?

A) 7 times as long
B) 14 times as long
C) 128 times as long
D) 256 times as long

Question 11

Someone who breaks encryption is called a ________.

A) cracker
B) coder
C) hacker
D) cryptanalyst

Question 12

Nearly all encryption for confidentiality uses symmetric key encryption ciphers.

Question 13

________ is the security guarantee that people who intercept messages cannot read them.

A) Integrity
B) Availability
C) Confidentiality
D) Encryption

Question 14

A ________ is a mathematical process used in encryption and decryption.

A) key
B) cipher
C) plaintext
D) coding method

Question 15

In order to be considered strong today, a symmetric encryption key must be at least ________ bits long.

A) 6
B) 8
C) 100
D) 1,000

Question 16

Which of the following statements accurately describes RC4?

A) RC4 is extremely fast.
B) RC4 always uses a 40-bit key.
C) Both A and B
D) Neither A nor B

Question 17

Nearly all encryption for confidentiality uses ________ encryption ciphers.

A) public key
B) symmetric key
C) hashing
D) None of the above

Question 18

A ________ is a random string of 40 to 4,000 bits (ones and zeros) used to encrypt messages.

A) key
B) cipher
C) plaintext
D) code

Question 19

________ ciphers move letters around within a message but characters are not substituted.

A) Transposition
B) Substitution
C) Both A and B
D) Neither A nor B

Question 20

To meet national export limitation in many countries, RC4 often uses a key length of ________ bits.

A) 8
B) 40
C) 100
D) 256

Question 21

In SSL/TLS, a ________ is a specific set of security methods and options.

A) cryptographic system standard
B) cipher suite
C) chosen set
D) tuple

Question 22

Packaged sets of cryptographic countermeasures for protecting data transmission are ________.

A) cryptographic standards
B) metacryptographic systems
C) cryptographic systems
D) All of the above

Question 23

Which of the following is one of the effective key lengths in 3DES?

A) 40 bits
B) 110 bits
C) Both A and B
D) Neither A nor B

Question 24

________ is efficient enough in processing power and RAM requirements to be used on small devices, such as PDAs and cell phones.

A) 3DES
B) AES
C) Both A and B
D) Neither A nor B

Question 25

The 56-bit key size ________.

A) is sufficient for major business transactions
B) is sufficient for most residential consumer applications
C) is considered a strong length
D) All of the above

Question 26

What protection do cryptographic systems provide on a message-by-message basis?

A) Message authentication
B) Message integrity
C) Message confidentiality
D) All of the above

Question 27

DES uses block encryption.

Question 28

In cryptographic systems, keying takes place during the second handshaking stage.

Question 29

Which of the following is one of the key lengths offered by AES?

A) 112 bits
B) 192 bits
C) Both A and B
D) Neither A nor B

Question 30

Proving your identity to a communication partner is ________.

A) validation
B) identification
C) authentication
D) certification

Question 31

Electronic signatures usually provide ________.

A) message-by-message authentication
B) message integrity
C) Both A and B
D) Neither A nor B

Question 32

When both parties prove their identities to the other, this is called ________.

A) mutual authentication
B) symmetric authentication
C) authentication
D) dual authentication

Question 33

________ occurs when companies believe they have good security because they are using proprietary ciphers that hackers do not know.

A) Security through obscurity
B) Weakest link ignorance
C) Reasonable protection
D) Hidden security

Question 34

In authentication, the party trying to provide its identity to the other party is called the applicant.

Question 35

What usually is the longest stage in a cryptographic system dialogue?

A) Ongoing communication
B) Negotiation of security methods and parameters
C) Keying
D) Mutual authentication

Question 36

Using new and proprietary encryption ciphers is a good idea because cryptanalysts will not know them.

Question 37

In cryptographic systems, the negotiation of security methods and options takes place during the ________ handshaking stage.

A) first
B) second
C) third
D) None of the above

Question 38

3DES is ________.

A) very slow
B) strong enough for communication in corporations
C) expensive in terms of processing cost
D) All of the above

Question 39

Someone who pretends to be someone else is ________.

A) a social engineer
B) a hacker
C) a cryptanalyst
D) an impostor

Question 40

Which of the following is one of the effective key lengths in 3DES?

A) 56 bits
B) 100 bits
C) 112 bits
D) None of the above

Question 41

In MS-CHAP, the ________ creates the response message.

A) supplicant
B) verifier
C) Both A and B
D) Neither A nor B

Question 42

When Joshua sends a message to Larry, Joshua will use ________ to encrypt the message.

A) the public key
B) Joshua's public key
C) Larry's public key
D) Larry's private key

Question 43

MS-CHAP provides mutual authentication.

Question 44

Cryptanalysts have found weaknesses in ________.

A) MD5
B) SHA-512
C) Both A and B
D) Neither A nor B

Question 45

What is the hash size of SHA-256?

A) 112 bits
B) 128 bits
C) 160 bits
D) 256 bits

Question 46

The most popular public key cipher is RSA.

Question 47

When Carol sends a message to Bob, Bob will use ________ to decrypt the message.

A) the private key
B) Carol's private key
C) Bob's private key
D) Carol's public key

Question 48

Which encryption method does MS-CHAP use?

A) Symmetric key encryption
B) Public key encryption
C) Both A and B
D) Neither A nor B

Question 49

Public key encryption is ________.

A) complex
B) slow
C) expensive
D) All of the above

Question 50

________ are proofs of identity.

A) Certifications
B) Credentials
C) Cartes
D) Verifications

Question 51

When a hashing algorithm is applied, the hash will ALWAYS have a fixed length.

Question 52

The hash size in MD-5 is 160 bits.

Question 53

The most popular public key encryption cipher is ________.

A) AES
B) DES
C) RSA
D) ECC

Question 54

When Emma sends a message to Lucy, Emma will use the public key to encrypt it.

Question 55

The hash size in SHA-1 is 160 bits.

Question 56

MS-CHAP is used for ________ authentication.

A) initial
B) message-by-message
C) Both A and B
D) Neither A nor B

Question 57

Hashing is a reversible process.

Question 58

Hashing is ________.

A) reversible
B) repeatable
C) Both A and B
D) Neither A nor B

Question 59

To be strong, ________ keys need to be longer than ________ keys.

A) public, symmetric
B) symmetric, public
C) Public and symmetric keys of about the same length have about equal strength.
D) None of the above

Question 60

In mutual authentication between two parties, ________.

A) there are two verifiers and two supplicants
B) there are two verifiers, but there is only one supplicant
C) there is one verifier, but there are two supplicants
D) None of the above.

Question 61

In public key encryption for authentication, the supplicant uses ________ to encrypt.

A) the supplicant's private key
B) the supplicant's public key
C) the verifier's private key
D) the verifier's public key

Question 62

Symmetric session key exchange can be done with public key encryption.

Question 63

Which of the following can be used as a keying method?

A) Public key encryption for confidentiality
B) MS-CHAP
C) Both A and B
D) None of the above

Question 64

The supplicant creates a digital signature by ________.

A) adding the password to the challenge message and hashing the two
B) hashing the plain text message
C) encrypting the message digest with its own private key
D) encrypting the message digest with its own public key

Question 65

In public key encryption for authentication, the supplicant must prove that it knows ________, which nobody else should be able to know.

A) the supplicant's public key
B) the supplicant's private key
C) the true party's private key
D) the verifier's private key

Question 66

Strong RSA keys are at least ________ bits long.

A) 100
B) 256
C) 512
D) 1,024

Question 67

For message-by-message authentication, each message must contain an electronic signature.

Question 68

Digital signatures provide ________.

A) message authentication
B) message integrity
C) Both A and B
D) Neither A nor B

Question 69

To test the digital signature, the verifier will use sender's public key.

Question 70

An attacker who captures the keying information in Diffie-Hellman key agreement can compute the symmetric session key.

Question 71

In checking the digital signature, the verifier ________.

A) decrypts the digital signature it received with the supplicant's public key to get the message digest
B) hashes the plaintext message with the same algorithm used by the sender to get the message digest
C) Both A and B
D) Neither A nor B

Question 72

Signing a message digest means encrypting it with the sender's public key.

Question 73

The supplicant creates a message digest by ________.

A) adding the password to the challenge message and hashing the two
B) hashing the plaintext message
C) encrypting the message digest with its own private key
D) None of the above.

Question 74

In public key encryption, "signing" is the act of ________.

A) adding the password to the challenge message and hashing the two
B) hashing the plain text message
C) encrypting the message digest with its own private key
D) encrypting the message digest with its own public key

Question 75

Digital signatures are used for ________ authentication.

A) initial
B) message-by-message
C) Both A and B
D) Neither A nor B

Question 76

In public key encryption for authentication, the verifier decrypts the ciphertext with the verifier's public key.

Question 77

Julia encrypts a message to David using public key encryption for confidentiality. After encrypting the message, can Julia decrypt it?

Question 78

Most message-by-message authentication methods provide message integrity as a by-products.

Question 79

The person the supplicant claims to be is the true party.

Question 80

In public key encryption for authentication, the verifier decrypts the ciphertext with the supplicant's public key.