I'm working on a project in my Linear Algebra class dealing with Encrypting and Decrypting text. I have been trying for hours to find the right commands to do this the way my professor wants. Here's the question:

(a) Encrypt the following (choosing your own 3x3 key matrix):

"This class is starting to get boring" (Not including the quotation marks. There are 36 characters in this phrase.)

Use blocks of size 3 (ie a 3x12 matrix with all the characters) and the alphabet: