AES Guest Lecturer

AES Algorithm
SubBytes
• SubBytes is the SBOX for AES
• This make AES a non-linear cryptographic system.
• For every value of b there is a unique value for b’
– It is faster to use a substitution table (and easier).
b' 0
b' 1
b' 2
b' 3
b' 4
b' 5
b' 6
b' 7
=
1 0 0 0 1 1 1 1
1 1 0 0 0 1 1 1
1 1 1 0 0 0 1 1
1 1 1 1 0 0 0 1
1 1 1 1 1 0 0 0
0 1 1 1 1 1 0 0
0 0 1 1 1 1 1 0
0 0 0 1 1 1 1 1
x 0
x 1
x 2
x 3
x 4
+
x 5
x 6
x 7
1
1
0
0
0
1
1
0
x is the inverse value of the byte b