Question

For the AES-128 algorithm there are __________ similar rounds and _________ round is different.

(a) 2 pair of 5 similar rounds ; every alternate

(b) 9 ; the last

(c) 8 ; the first and last

(d) 10 ; no

I had been asked this question in an international level competition.

This intriguing question comes from The AES Algorithm topic in division Advanced Encryption Algorithm and Block Cipher Operation of Cryptograph & Network Security

Answer 1

Correct answer is (b) 9 ; the last

To explain I would say: In the AES-128 there are 9 similar rounds and the last round is different.