I am extremely new to cryptography and AES and so I am not confident that I did this question orrectly. Please can you check my answers and let me know if anything jumps out as incorrect, Thank you!
Here is the Question:
Consider the key expansion procedure for AES encryption.
The given four subkeys are: w4 = a0f afe17, w5 = 88542cb1, w6 = 23a33939 and w7 = 2a6c7605 using hexadecimal notation.
(a) Complete the following procedure to generate the next subkey w8.
i. Generate the temporary subkey wt = w______.
ii. Rotate (round-end) the binary sequence wt to the left for 8 positions and obtain wt =______.
iii. Substitute wt byte by byte using Table 1 and obtain wt =_______ .
iv. Generate the round constant r8 =________ for w8.
v. wt = wt ⊕ r8 =_________ .
vi. w8 = wt ⊕ w4 = ________.
i) wt = w4 = a0fafe17 ii) Eight positions in binary = two positions in Hex: wt = fafe17a0 iii) wt = adbbf0e0 iv) r8 = [ rc8 00 00 00] rc8 = 2*rc7 = 2*2a = 54 r8 = [ 54 00 00 00 ] v) wt = wt ⊕ r8 = f9bbf0e0 vi) w8 = wt ⊕ w4 = 59410ef7