The Playfair cipher is much more complicated than the Vigenere or any other cipher we have seen so far, there is no guaranteed method that will work if you are trying to break a Playfair cipher by hand. You need a huge amount of text and a lot of time. With a computer there is an algorithm that will work easily for decrypting Playfair ciphers. It also will decrypt Monoalphabetic Substitution ciphers, and can find the optimal solution to a scrambled Rubik's cube. It is called the Hill-Climbing algorithm.


To decrypt it by hand, you want to play around with the key array and find the key, then you can decrypt the ciphertext. You are almost guaranteed that the last row of the key array is W X Y Z because these letters will rarely come in the key word. Start from there and try to decrypt part of the ciphertext using only that row, then guess possible words. If the ciphertext has spaces in it, guess that some of the 3 letter words are 'the'.