Question

Which of the following are true

i) In the AES key expansion algorithm, the function g() operates on w i+3

ii) Perform a one-byte right circular rotation on the argument 4-byte word

iii) The round constant follows the formula RC[j] = RC[j − 1]

(a) i), ii)

(b) ii) only

(c) i) only

(d) All

I got this question by my school teacher while I was bunking the class.

The query is from The AES Algorthm topic in division Advanced Encryption Algorithm and Block Cipher Operation of Cryptograph & Network Security

Answer 1

Right answer is (c) i) only

To explain I would say: Only the first option is true. There is a left circular rotation in AES key expansion. RC[j] = 2 × RC [j − 1] is the formula for the round constant.