Question

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

This question was posed to me in an online interview.

The query is from Secure Hash Algorithms (SHA) in section Other Public Key Cryptosystems and Cryptographic Hash Functions of Cryptograph & Network Security

Answer 1

The correct answer is (a) by taking the first 64 bits of the fractional parts of the cube roots of the first 80 prime numbers

To explain: 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.