Helpful info I have found so far:

>
> mess1 := "This class is starting to get boring";
nums1 := `mod`(convert(mess1, bytes), 29);
mykey := `mod`(Matrix(3, 3, {(1, 1) = 3, (1, 2) = 5, (1, 3) = 8, (2, 1) = 9, (2, 2) = 3, (2, 3) = 7, (3, 1) = 2, (3, 2) = 8, (3, 3) = 6}), 29);

This will convert my phrase into "bytes" mod 29. I'm not exactly sure what the phrase "bytes" means, though.

Also, a very important question:

I typed my matrix into Maple using the "Matrix" command. It was a 3x12 matrix, and Maple will not display it. How do I get maple to display a 3x12 matrix?