The main problem with this cipher code is that you can easily crack the code of the message by judging the frequency of the message. Example, the word ‘the’ is a word that is unavoidable in a sentence so if the same cluster appears commonly and is in 3 letter format, then this word may just be the letter ‘the’. The problem with the encryption method is once you find out the code, the whole message is clear. A way to tackle the problem is to every letter has a different code. This would make the code harder to crack but and frustrating.