Ciphered message:
3 2 3 4 1 0 4 4
2 2 4 3 1 1 3 4
3 3 4 4 4 5 1 1
3 4 4 4 4 5 1 2
2 2 1 1 3 4 5 5
2 2 2 1 4 3 5 4
2 3 1 1 3 3 2 1
2 2 0 0 3 3 1 1
Deciphered message:
Incomprehensible
Ciphered message:
3 2 3 4 1 0 4 4
2 2 4 3 1 1 3 4
3 3 4 4 4 5 1 1
3 4 4 4 4 5 1 2
2 2 1 1 3 4 5 5
2 2 2 1 4 3 5 4
2 3 1 1 3 3 2 1
2 2 0 0 3 3 1 1
Deciphered message:
Incomprehensible
To decipher, split the grid into 16 2-by-2 boxes, take the total in each box, translate numbers 1-26 to letters A-Z, and read in the usual order:
3 2|3 4|1 0|4 4 I N C O
2 2|4 3|1 1|3 4
---+---+---+---
3 3|4 4|4 5|1 1 M P R E
3 4|4 4|4 5|1 2
---+---+---+---
2 2|1 1|3 4|5 5 H E N S
2 2|2 1|4 3|5 4
---+---+---+---
2 3|1 1|3 3|2 1 I B L E
2 2|0 0|3 3|1 1
To encode, do the reverse, splitting each letter's value into four numbers as evenly as possible, for example 9 = 3 + 2 + 2 + 2. I don't know if there's a logic to how these are ordered within each 2-by-2 box or if it's arbitrary -- note that the letter's E's 2 + 1 + 1 + 1 is ordered in 3 different ways.