Lecture 8

Question 1

A poly-alphabetic substitution cipher used in WWII by the Germans used a machine named what?

Answer 1

Enigma

Question 2

A mono-alphabetic substitution does what?

Answer 2

Rotates the letters of the alphabet X places

Question 3

A mono-alphabetic substitution cipher is susceptible to what?

Answer 3

frequency analysis

Question 4

The 4 fundamental goals of cryptography are:

Answer 4

Confidentiality
Integrity
Authentication
Non-repudiation

Question 5

What type of cryptography is used to provide confidentiality?

A. symmetric
B. asymmetric
C. either/both

Answer 5

C. either/both

Question 6

Cryptographic algorithms rely upon _____ (crypto-variables)

Answer 6

keys

Question 7

In private key, participants use what?

A. unshared keys (all participants have their own)
B. shared keys (all participants share a key)

Answer 7

B. shared keys (all participants share a key)

Question 8

In public key, participants use what?

A. unshared keys (all participants have their own)
B. shared keys (all participants share a key)

Answer 8

A. unshared keys (all participants have their own) (public/private keys)

Question 9

The art and science of creating and implementing secret codes and ciphers

Answer 9

cryptography

Question 10

The study of methods to defeat codes and ciphers

Answer 10

crypanalysis

Question 11

What are true of Kerchoff’s principle? select all that apply

A. they should be known and public
B. they should be kept secret
C. keys should remain private
D. weaknesses are unknown

Answer 11

A. they should be known and public

C. keys should remain private

Question 12

In the AND operations, 1 is returned when what?

Answer 12

When both X and Y are 1.

Question 13

In the OR operations, 1 is returned when what?

Answer 13

When at least X or Y is 1.

Question 14

In XOR operations, 1 is returned when what?

Answer 14

When only X or Y is 1, but not both.

Question 15

The _______ function is the remainder of the division of one number by another.
EX: 10 Mod 3 is 1

A. Division
B. Multiplicity
C. Modular
D. Modulo

Answer 15

D. Modulo

Question 16

_____ occurs when the relationship between the plain text and the key is so complicated an attacker can’t continue altering the plain text and analyze to determine the key.

A. confusion
B. diffusion
C. encryption

Answer 16

A. Confusion

Question 17

_____ occurs when a change in the plain text results in many changes spread throughout the cipher text.

A. confusion
B. diffusion
C. encryption

Answer 17

B. Diffusion

Question 18

A nonce is what?

Answer 18

random number generator

Question 19

_____ is when the information/privilege required to perform an operation is divided among multiple users.

A. shared knowledge
B. split knowledge
C. separated knowledge

Answer 19

B. split knowledge

Question 20

What is M of N control?

Answer 20

the minimum number of agents (M) out of the total number of agents (N) work together to perform high security task.

Question 21

The cryptographic strength is determined by measuring what?

Answer 21

The effort to break it

Question 22

A _____ is a cryptographic system of symbols that represent words or phrases.

A. Code
B. Cipher

Answer 22

A. Code

Question 23

A _____ is always meant to hide the true meaning of a message.

A. Code
B. Cipher

Answer 23

B. Cipher

Question 24

A ____ cipher rearranges the letters of a plain-text message.

Answer 24

transposition

Question 25

A ____ cipher uses an encryption algorithm to replace each character or bit of the plain-text message with a different one.

Answer 25

substitution

Question 26

A _____ uses different substitution alphabet for each letter. It is a very long series of numbers.

Answer 26

one-time pad

Question 27

A _____ cipher is as long as the message itself and it usually chosen from a common book.

Answer 27

running key (book)

Question 28

A longer key usually provides what? A. stronger encryption B. weaker encryption

Answer 28

A. stronger encryption

Question 29

Modern cryptographic system have a key size of at least what?

Answer 29

128 bit

Question 30

Bulk encryption is primarily used with what type of cryptography?

Answer 30

Symmetric key (secret/private key cryptography)

Question 31

What are true of symmetric key cryptography. ``` A. uses a small key B. needs a secure method of exchanging the key C. does not provide nonrepudiation D. scalable E. uses a large key F. fast ```

Answer 31

B. needs a secure method of exchanging the key C. does not provide nonrepudiation E. uses a large key F. fast

Question 32

What are true of asymmetric key cryptography. ``` A. it uses a private and public key B. provides nonrepudiation C. scalable D. fast E. difficult key revocation F. key distribution is simple ```

Answer 32

A. it uses a private and public key B. provides nonrepudiation C. scalable F. key distribution is simple

Question 33

A _____ transforms a variable-size input and returns a fixed-size string.

Answer 33

hashing algorithm

Question 34

_____ is a 64-bit block cipher that has 5 modes of operation. The key is 56 bits long and uses XOR operations run through 16 times. A. SHA B. AES C. PSK D. DES

Answer 34

D. DES

Question 35

_____ replaced DES and uses lengths and block sizes of 128, 192 and 256 bits. A. SHA B. AES C. PSK D. DES

Answer 35

B. AES

Question 36

What are the 3 methods used to exchange secret keys securely.

Answer 36

Offline distribution public key encryption diffie-hellman key exchange algorithm