AES Guest Lecturer

AES Algorithm
AddRoundKey
• The state is XORed into the expanded key Nr +
1 times.
• This is the same as adding the expanded key to
the state Nr+1 times in GF(2 8 )
– in GF(2 8 ) adding two numbers together is the same
as XORing them.
void AddRoundKey(byte[][] state) {
for (int c = 0; c < Nb; c++)
for (int r = 0; r < 4; r++)
state[r][c] = state[r][c] ˆ w[wCount++];}
global counter