Rijndael Mix Columns - InverseMixColumns

InverseMixColumns

The MixColumns operation has the following inverse (numbers are decimal):

\begin{bmatrix}r_0\\r_1\\r_2\\r_3\end{bmatrix} = \begin{bmatrix} 14&11&13&9 \\ 9&14&11&13 \\ 13&9&14&11 \\ 11&13&9&14 \end{bmatrix} \begin{bmatrix}a_0\\a_1\\a_2\\a_3\end{bmatrix}

Or:

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