Polygraphic Substitution

Encrypting using matrixes.

Example

With the message $ACT$ and the matrix $MYSUPERKE$ We create a matrix:

$$M_{key}=\left[\begin{array}{ccc}6& 24& 1\\ 13& 16& 10\\ 7& 21& 13\end{array}\right]$$ $$M_{message}=\left[\begin{array}{c}5\\ 8\\ 14\end{array}\right]$$