Deck 3: Cryptography Key, Algorithm, and Mode of Operation

Question 1

If the key is 110100001, the output of the SP network for the plaintext: 101110001 is

A)110100011
B)110101110
C)10110111
D)11111010

Answer 1

110101110

Question 2

What is the number of possible 3 x 3 affine cipher transformations

A)168
B)840
C)1024
D)1344

Answer 2

1344

Question 3

What is the expanded key size of AES-192?

A)44 words
B)60 words
C)52 words
D)36 words

Answer 3

52 words

Question 4

In affine block cipher systems if f(m)=Am + t, what is f(m1+m2+m3) ?

A)f(m1) + f(m2) + f(m3) + t
B)f(m1) + f(m2) + f(m3) +2t
C)f(m1) + f(m2) + f(m3)
D)2(f(m1) + f(m2) + f(m3))

Question 5

The 4×4 byte matrices in the AES algorithm are called

A)states
B)words
C)transitions
D)permutations

Question 6

If the block size is 's', how many affine transformations are possible ?

A)2s (2s-1)(2s-1)(2s-12) ………(2s-1(s-1))
B)2s (2s-1)(2s-2)(2s-22) ………(2s-2(s-2))
C)2ss (2s-1)(2s-2)(2s-22) ………(2s-2(s-1))
D)2s (2s-1)(2s-2)(2s-22) ………(2s-2(s-3))

Question 7

For the AES-128 algorithm there are__________ similar rounds and_________round is different.

A)2 pair of 5 similar rounds ; every alternate
B)9 ; the last
C)8 ; the first and last
D)10 ; no

Question 8

The DES Algorithm Cipher System consists of _________rounds (iterations) each with a round key

A)9
B)12
C)18
D)16

Question 9

DES follows

A)hash algorithm
B)caesars cipher
C)feistel cipher structure
D)sp networks

Question 10

Every cyclic group is_______.

A)a group with finite order
B)a group with prime order
C)a non abelian group
D)an abelian group

Question 11

In the DES algorithm the round key is_________bit and the Round Input is__________bits

A)48, 32
B)64,32
C)56, 24
D)32, 32

Question 12

__________is not a binary operation on the set of natural numbers.

A)addition
B)product
C)difference
D)none

Question 13

In the DES algorithm the Round Input is 32 bits, which is expanded to 48 bits via

A)scaling of the existing bits
B)duplication of the existing bits
C)addition of zeros
D)addition of ones

Question 14

Which of the following is group under multiplication?

A)q
B)q-{0}
C)q-{1}
D)q-{0,1}

Question 15

The Initial Permutation table/matrix is of size

A)16×8
B)4×8
C)12×8
D)8×8

Question 16

The number of unique substitution boxes in DES after the 48 bit XOR operation are

A)8
B)4
C)6
D)12

Question 17

The DES algorithm has a key length of

A)128 bits
B)32 bits
C)64 bits
D)16 bits

Question 18

What is the size of the key in the SDES algorithm?

A)24 bits
B)16 bits
C)20 bits
D)10 bits

Question 19

The Plaintext for the Ciphertext 10100101, given that the key is 0010010111 is

A)1100111
B)110110
C)1001000
D)1001100

Question 20

Assume input 10-bit key, K: 1010000010 for the SDES algorithm. What is K1?

A)10100100
B)1011011
C)1101000
D)10100111

Question 21

Assume input 10-bit key, K: 0010010111 for the SDES algorithm. What is K2?

A)11101010
B)11011011
C)1101000
D)10101111

Question 22

Which of the following is a mode of operation for the Block ciphers in cryptography?

A)a. electronic code book (ecb)
B)cipher block chaining (cbc)
C)counter (ctr) mode
D)all of the above

Question 23

Which of the following modes of operations can be followed for both stream ciphers as well as block ciphers?

A)a. cbc (cipher block chaining)
B)ecb (electronic code book)
C)a. cfb (cipher text feed back)
D)all of the above

Question 24

The Plaintext for the Ciphertext 00001111, given that the key is 1111111111 is

A)1100111
B)1010
C)11111111
D)1101101

Question 25

Which one of the following RC4 algorithm not used in?

A)ssl
B)tls
C)ftp
D)wep