This set of Cryptography Multiple Choice Questions & Answers (MCQs) focuses on “Secure Hash Algorithms (SHA) – 1”.

1. SHA-1 produces a hash value of

a) 256 bits

b) 160 bits

c) 180 bits

d) 128 bits

View Answer

Explanation: 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

View Answer

Explanation: 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

View Answer

Explanation: 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) 2^{128}

b) 2^{256}

c) 2^{64}

d) 2^{192}

View Answer

Explanation: The maximum length of the message is 2

^{128}.

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

View Answer

Explanation: 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

View Answer

Explanation: 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

View Answer

Explanation: 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

View Answer

Explanation: 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

View Answer

Explanation: The round constants (K) is 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

View Answer

Explanation: 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

View Answer

Explanation: 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

View Answer

Explanation: (b, c, d, f, g, and h) undergo permutations.

**Sanfoundry Global Education & Learning Series – Cryptography and Network Security.**

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