Symmetric Encryption

Question 1

A block cipher should use substitution to achieve confusion

Answer 1

trueP2 L6

Question 2

A block cipher should user _______ to achieve diffusion

Answer 2

permutationP2 L6

Question 3

a block cipher should use a few rounds, each with a combination of _________ and ____________

Answer 3

substitution, permutationP2 L6

Question 4

Block cipher algorithms should be kept secret

Answer 4

falseP2 L6

Question 5

An S-box substitutes a ____ bit value with a ____ bit value

Answer 5

6 bit value with a 4 bit value using a predefined tableP2 L6

Question 6

To decrypt using DES, the same algorithm is used, but with per-round keys are used in the reverse order

Answer 6

trueP2 L6

Question 7

With triple-DES, the effective key length can be 56, 112, and 168

Answer 7

trueP2 L6

Question 8

Each round of DES contains both substitution and permutation operations

Answer 8

trueP2 L6

Question 9

The logics behind S-boxes are well-known and verified

Answer 9

false; they’ve been kept secretP2 L6

Question 10

To decrypt using AES, just run the same algorithm in the same order of operations

Answer 10

false (algorithm is run in reverse)P2 L6

Question 11

Each operation or stage in AES is reversible

Answer 11

trueP2 L6

Question 12

AES can support key length of ___, ___, ____

Answer 12

128, 192, 256P2 L6

Question 13

AES is much more efficient than Triple DES

Answer 13

trueP2 L6

Question 14

Which is more secure, CBC or ECB?

Answer 14

CBCP2 L6

Question 15

We can protect both confidentiality and integrity protection with CBC by using just one key

Answer 15

falseP2 L6