1. SHA-1 produces a hash value of
a) 256 bits
b) 160 bits
c) 180 bits
d) 128 bits
Answer
Answer: b [Reason:] SHA-1 produces a hash value of 160 bits.
2. What is the number of round computation steps in the SHA-256 algorithm?
a) 80
b) 76
c) 64
d) 70
Answer
Answer: c [Reason:] The number of round computation steps in the SHA-256 algorithm is 64.
3. In SHA-512, the message is divided into blocks of size ___ bits for the hash computation.
a) 1024
b) 512
c) 256
d) 1248
Answer
Answer: a [Reason:] The message is divided into blocks of size 1024 bits, and the output produced is a 512 bit message digest.
4. What is the maximum length of the message (in bits) that can be taken by SHA-512?
a) 2128
b) 2256
c) 264
d) 2192
Answer
Answer: a [Reason:] The maximum length of the message is 2128.
5. The message in SHA-512 is padded so that it’s length is
a) 832 mod 1024
b) 768 mod 1024
c) 960 mod 1024
d) 896 mod 1024
Answer
Answer: d [Reason:] Padding is done so that the length is 896 mod 1024.
6. The big-endian format is one in which
a) the least significant byte is stored in the low-address byte position
b) the least significant byte is stored in the high-address byte position
c) the most significant byte is stored in the high-address byte position
d) the most significant byte is stored in the low-address byte position
Answer
Answer: d [Reason:] The big-endian format is one in which the most significant byte is stored in the low-address byte position.
7. In SHA-512, the registers ‘a’ to ‘h’ are obtained by taking the first 64 bits of the fractional parts of the cube roots of the first 8 prime numbers.
a) True
b) False
Answer
Answer: b [Reason:] The registers ‘a’ to ‘h’ are obtained by taking the first 64 bits of the fractional parts of the square roots of the first 8 prime numbers.
8. What is the size of W (in bits) in the SHA-512 processing of a single 1024- bit block?
a) 64
b) 128
c) 512
d) 256
Answer
Answer: a [Reason:] The 1024 bit message blocks are compressed to form 64 bit values(W).
9. In the SHA-512 processing of a single 1024- bit block, the round constants are obtained
a) by taking the first 64 bits of the fractional parts of the cube roots of the first 80 prime numbers
b) by taking the first 64 bits of the fractional parts of the cube roots of the first 64 prime numbers
c) by taking the first 64 bits of the fractional parts of the square roots of the first 80 prime numbers
d) by taking the first 64 bits of the non-fractional parts of the first 80 prime numbers
Answer
Answer: a [Reason:] The round constants (K) are obtained by taking the first 64 bits of the fractional parts of the cube roots of the first 80 prime numbers.
10. The output of the N 1024-bit blocks from the Nth stage is
a) 512 bits
b) 1024 bits
c) N x 1024bits
d) N x 512 bits
Answer
Answer: a [Reason:] The message digest output is 512-bits.
11. 
What does the figure represent?
a) Compression function
b) Message digest generation using SHA
c) Elementary SHA operation for single round
d) Processing of a single 1024 bit block
Answer
Answer: c [Reason:] The figure represents the elementary SHA operation for single round.
12. Among the registers ‘a’ to ‘h’ how many involve permutation in each round?
a) 4
b) 5
c) 6
d) 3
Answer
Answer: c [Reason:] (b, c, d, f, g, and h) undergo permutations.
