Show the process of Encoding and decoding the sentence "STAY SAFE" with the following key matrix using Cryptography.
2 1 3 2 2 1
1 1 2
Use the following chart as a reference for numbers assigned to each letter in the alphabet
0
Space A B c D E F G H
13 14 15 16 17 18 19 20 21 22 23 24 25
M
1 2 3 4 5 6 7
N 0
P
Q R S T U V W x Y
8 9 10 11 12 26
J K L z