This set of Cryptography Multiple Choice Questions & Answers (MCQs) focuses on “Whirlpool Algorithm- 2”.

1. What is the correct order of operation within each round of the Whirlpool algorithm?

a) Add round key, Substitute bytes, Mix rows, Shift columns

b) Substitute bytes, Add round key, Shift columns, Mix rows

c) Mix rows, Substitute bytes, Shift columns, Add round key

d) Substitute bytes, Shift columns, Mix rows, Add round key

View Answer

Explanation: The correct order is Substitute bytes, Shift columns, Mix rows, Add round key.

2. What is the size of the s-box table/matrix in Whirlpool?

a) 8 × 8

b) 16 × 16

c) 8 × 16

d) 16 × 8

View Answer

Explanation: The size of the matrix is 16 × 16.

3. The S-box implements linear mapping thus providing diffusion.

a) True

b) False

View Answer

Explanation: Non-linear mapping provides diffusion. The s-box provides Non-linear mapping.

4. Another name for the Whirlpool key is

a) CState

b) LState

c) Estate

d) KState

View Answer

Explanation: Whirlpool uses a 512 bit key called KState.

5. How many round constants (RCs) are required in Whirlpool?

a) 10

b) 11

c) 12

d) 21

View Answer

Explanation: There are 10 RCs required for modifying 10 Keys in each step.

6. The Round Constant is dependent on the s-box values.

a) True

b) False

View Answer

Explanation: The Round Constant is given by S[8(r-1)+j] where S is the s-box permutation.

7. The Round Constant is given by S[8(r-1)+j]. What are the limits of ‘r’?

a) 0 <= r <= 11

b) 0 <= r <= 12

c) 0 <= r <= 10

d) 0 <= r <=16

View Answer

Explanation: r can have values from 0 to 10.

8. When the Round Constant is given by S[8(r-1)+j]. What are the limits of ‘i’ and ‘j’?

a) i = 1 ; 0 <= j <= 7

b) i = 0 ; 0 <= j <= 7

c) 0 <= i <= 7; 0 <= j <= 7

d) 0 <= i <= 7; j=0

View Answer

Explanation: All rows except the first one are 0 i.e. RC=0 for ‘i’ not equal to 0.

9. The 7th row in the 8 × 8 matrix undergoes a ___________ shift.

a) 6 bit

b) 6 byte

c) 7 bit

d) 7 byte

View Answer

Explanation: The nth row in the 8 × 8 matrix undergoes an (n-1) byte shift.

10. How many XOR gate operations are involved in the S-box permutation?

a) 12

b) 8

c) 16

d) 4

View Answer

Explanation:12 XORs are involved in the S-box permutation in Whirlpool.

11. Which round provides linear diffusion in the Whirlpool Algorithm?

a) Add Key

b) Substitute Bytes

c) Mix Rows

d) Shift Rows

View Answer

Explanation: MR function is the linear diffusion layer of the Whirlpool block cipher.

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