1. In SHA-3, which step function does the operation L[2,3] <- L[2,3] XOR NOT(L[3,3]) AND L[4,3] represent?
a) Theta
b) Rho
c) Pi
d) Chi
Answer
Answer: d [Reason:] The above operation represents the chi step function.
2. In SHA-3, which function does the operation L[2,3]<- C[1] XOR L[2,3] XOR ROT(C[3],1) represent?
a) Theta
b) Rho
c) Pi
d) Chi
Answer
Answer: a [Reason:] The above operation represents the theta step function.
3. How many rounds are present in each iteration function of SHA-3?
a) 3
b) 4
c) 5
d) 6
Answer
Answer: c [Reason:]Each Iteration of the SHA-3 algorithm has 5 step functions.
4. In SHA-3, which step function does not affect W [0, 0]?
a) Theta
b) Iota
c) Pi
d) Chi
Answer
Answer: c [Reason:] Pi and Rho step functions do not cause any change on W [0, 0].
5. Which among the following is not a substitution operation?
a) Theta
b) Iota
c) Pi
d) Chi
Answer
Answer: c [Reason:] Pi and Rho are permutation operations.
6. In SHA-3, for a message digest size of 256, what is the bitrate ‘r’ (capacity = 512) ?
a) 576
b) 1088
c) 1152
d) 832
Answer
Answer: b [Reason:] In SHA-3, c+r = 1600, therefore here ‘r’ = 1088.
7. The sponge construction involves 2 phases, these are
a) absorbing and adaptive
b) adaptive and squeezing
c) absorbing and squeezing
d) none of the mentioned
Answer
Answer: c [Reason:] The sponge construction involves 2 phases – the absorbing phase and the squeezing phase.
8. Within the Keccak function-f, the 1600 bits are arranged into a 5 x 5 x 64 array a. The 64-bit units are referred to as
a) lemma
b) z co-ordinate
c) kernel
d) lanes
Answer
Answer: d [Reason:] They are referred to as lanes.
9. What are the co-ordinates of the bottom-right most lane?
a) L[4 ,4].
b) L[4, 0].
c) L[5, 5].
d) L[5, 1].
Answer
Answer: b [Reason:] The bottom right most lane corresponds to x=4 and y=0 i.e. L[4, 0].
10. How many iterations / rounds does the Keccak function have ?
a) 12
b) 36
c) 16
d) 24
Answer
Answer: d [Reason:] The Keccak function has 24 rounds, each of which has 5 step functions.
11. Which step function works only W[0, 0]?
a) Theta
b) Iota
c) Pi
d) Chi
Answer
Answer: b [Reason:] The last step function Iota works only on W[0, 0].
12. SHA-3 has an advantage over other algorithms because, there is no need for table look ups, arithmetic operations or data dependent operations.
a) True
b) False
Answer
Answer: a [Reason:] The statement is true. SHA-3 does not require look-up tables, and is thus easily implemented on both hardware and software.
