Deck 5: Advanced Encryption Standard

Question 1

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

Answer 1

True

Question 2

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

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

Answer 2

A

Question 3

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

Answer 3

True

Question 4

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

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

Question 5

AES uses a Feistel structure.

Question 6

The AES cipher begins and ends with an)_________ 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 7

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 8

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

Question 9

Division requires that each nonzero element have an)__________ inverse.

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

Question 10

InvSubBytes is the inverse of ShiftRows.

Question 11

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

Question 12

The ordering of bytes within a matrix is by column.

Question 13

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

Question 14

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

Question 15

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

Question 16

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

Question 17

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

Question 18

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

Question 19

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

Question 20

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

Question 21

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

A)Z_p
B)a/b = ab^-1)
C)GF2^n-1)
D)GF2⁸)

Question 22

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

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

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)256-bit
C)128-bit
D)64-bit

Question 25

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

Question 26

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

Question 27

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

Question 28

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

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

Question 29

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

Question 30

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 31

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 32

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 performed.This transformation is called __________ .

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

Question 33

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

Question 34

In the AES structure both encryption and decryption ciphers begin with an) __________ 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 35

__________ 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 36

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 37

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

Question 38

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 39

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

Question 40

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

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

Question 41

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

Question 42

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

Question 43

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

Question 44

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

Question 45

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