Deck 6: Advanced Encryption Standard

Question 1

A __________ is a set in which you can do addition, subtraction, multiplication and division without leaving the set.

A)record
B)standard
C)field
D)block

Answer 1

C

Question 2

the Rijndael developers designed the expansion key algorithm to
be resistant to known cryptanalytic attacks.

Answer 2

True

Question 3

InvSubBytes is the inverse of ShiftRows.

Answer 3

False

Question 4

In Advanced Encryption Standard all operations are performed on __________ bytes.

A)8-bit
B)16-bit
C)32-bit
D)4-bit

Question 5

the inverse add round key transformation is identical to the
forward add round key transformation because the XOR
operation is its own inverse.

Question 6

Virtually all encryption algorithms, both conventional and public-
key, involve arithmetic operations on integers.

Question 7

AES can be implemented very efficiently on an 8-bit processor.

Question 8

Compared to public-key ciphers such as RSA, the structure of AES
and most symmetric ciphers is quite complex and cannot be
explained as easily as many other cryptographic algorithms.

Question 9

Division requires that each nonzero element have a(n) __________ inverse.

A)multiplicative
B)divisional
C)subtraction
D)addition

Question 10

DES is a block cipher intended to replace AES for commercial
applications.

Question 11

the Advanced Encryption Standard was published by the __________ in 2001.

A)ARK
B)FIPS
C)IEEE
D)NISt

Question 12

AES uses a Feistel structure.

Question 13

the nonlinearity of the S-box is due to the use of the multiplicative
inverse.

Question 14

As with any block cipher, AES can be used to construct a message
authentication code, and for this, only decryption is used.

Question 15

At each horizontal point, State is the same for both encryption and
decryption.

Question 16

the AES cipher begins and ends with a(n) _________ stage because any other stage, applied at the beginning or end, is reversible without knowledge of the key and
Would add no security.

A)Substitute bytes
B)AddRoundKey
C)MixColumns
D)ShiftRows

Question 17

the ordering of bytes within a matrix is by column.

Question 18

In the Advanced Encryption Standard the decryption algorithm is
identical to the encryption algorithm.

Question 19

the transformations AddRoundKey and InvMixColumn alter the
sequence of bytes in State.

Question 20

the S-box is designed to be resistant to known cryptanalytic
attacks.

Question 21

the __________ is when a small change in plaintext or key produces a large change in the ciphertext.

A)avalanche effect
B)Rcon
C)key expansion
D)auxiliary exchange

Question 22

the final round of both encryption and decryption of the AES structure consists of __________ stages.

A)one
B)two
C)three
D)four

Question 23

the cipher consists of N rounds, where the number of rounds depends on the __________ .

A)key length
B)output matrix
C)State
D)number of columns

Question 24

the AES key expansion algorithm takes as input a four-word (16-byte) key and produces a linear array of __________ words (176 bytes).

Question 25

In the AddRoundKey transformation the 128 bits of State are bitwise XORed with the _________ of the round key.

A)64 bits
B)128 bits
C)256 bits
D)512 bits

Question 26

the encryption round has the structure:

A)ShiftRows, MixColumns, SubBytes, InvMixColumns
B)SubBytes, ShiftRows, MixColumns, AddRoundKey
C)MixColumns, ShiftRows, SubBytes, AddRoundKey
D)InvShiftRows, InvSubBytes, AddRoundKey, InvMixColumns

Question 27

the __________ is a block cipher intended to replace DES for commercial applications.It uses a 128-bit block size and a key size of 128, 192, or 256 bits.

Question 28

the first N - 1 rounds consist of four distinct transformation functions: SubBytes, ShiftRows, AddRoundKey, and __________ .

Question 29

In the general structure of the AES encryption process the input to the encryption and decryption algorithms is a single _________ block.

A)32-bit
B)64-bit
C)128-bit
D)256-bit

Question 30

the cipher consists of N rounds, where the number of rounds depends on the __________ .

Question 31

__________ affects the contents of bytes in State but does not alter byte sequence and does not depend on byte sequence to perform its transformation.

A)InvSubBytes
B)ShiftRows
C)SubBytes
D)InvShiftRows

Question 32

In the AES structure both encryption and decryption ciphers begin with a(n) __________ stage, followed by nine rounds that each include all four stages,
Followed by a tenth round of three stages.

A)Substitute bytes
B)AddRoundKey
C)MixColumns
D)ShiftRows

Question 33

In AES, the arithmetic operations of addition, multiplication and division are performed over the finite field _________ .

A)Z_p
B)a/b = a(b^-1)
C)GF(2^n-1)
D)GF(2⁸)

Question 34

AES processes the entire data block as a single matrix during each round using __________ and permutation.

Question 35

the four separate functions of the Advanced Encryption Standard are: permutation, arithmetic operations over a finite field, XOR with a key, and __________ .

Question 36

the first row of State is not altered; for the second row a 1-byte circular left shift is performed; for the third row a 2-byte circular left shift is performed; and
For the fourth row a 3-byte circular left shift is performe
D)this transformation
Is called __________ .

A)AddRoundKey
B)ShiftRows
C)MixColumns
D)Substitute bytes

Question 37

the National Institute of Standards and technology chose the __________ design as the winning candidate for AES.

Question 38

the _________ transformation operates on each column individually.Each byte of a column is mapped into a new value that is a function of all four bytes in that column.

Question 39

the mix column transformation combined with the __________ transformation ensures that after a few rounds all output bits depend on all input bits.

Question 40

the forward substitute byte transformation, called _________ , is a simple table lookup.

Question 41

A polynomial m(x) is called __________ if and only if m(x) cannot be expressed as a product of two polynomials, both of degree lower than that of m(x).

Question 42

An example of a finite field is the set Zp consisting of all the integers {0, 1, ..., p - 1}, where p is a __________ and in which arithmetic is carried out modulo p.

Question 43

A more efficient implementation can be achieved for a 32-bit processor if operations are defined on _________ words.

Question 44

the standard decryption round has the structure InvShiftRows, InvSubBytes, __________, InvMixColumns.

Question 45

___________ affects the sequence of bytes in State but does not alter byte contents and does not depend on byte contents to perform its transformation.