AES Guest Lecturer
AES Guest Lecturer
AES Guest Lecturer
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<strong>AES</strong> Algorithm - InvMixColumns<br />
a ’ 0<br />
a ’ 1<br />
a ’ 2<br />
a ’ 3<br />
=<br />
0e 0b 0d 09<br />
09 0e 0b 0d<br />
0d 09 0e 0b<br />
a 0<br />
a 1<br />
a 2<br />
a 3<br />
0b 0d 09 0e a 3<br />
To Multiply in GF(2 8 ) :<br />
a * 09 = a * (08 ⨁ 01)<br />
= (a * 02 * 02 * 02) ⨁ (a * 01)<br />
a * 0b = a * (08 ⨁ 02 ⨁ 01)<br />
= (a * 02 * 02 * 02) ⨁ (a * 02) ⨁ (a * 01)<br />
a * 0e = a * (08 ⨁ 04 ⨁ 02)<br />
= (a * 02 * 02 * 02) ⨁ (a * 02 * 02) ⨁ (a * 02)