Modification of Playfair Chiper to strengthen Playfair Chiper algorith with 2 Key Layer Matrix (KLM) method

Playfair ciphers are one of the popular classic encryption methods that are difficult to manipulate manually, but this method has many drawbacks because they only use uppercase or lowercase letters. This makes the combination easier to be guessed, even though it takes time. This study attempts to modify the playfaircryptographic algorithm key matrix with the Key Layer Matrix (KLM) method, by changing the 5x5 key matrix in 2 layers, so that the key combination becomes 25 x 25 consisting of upper and lower case letters. To perfect this modification, the key used is two, the key for layer 1 and the key for layer 2. The results of the calculations, with this method, make the complexity of the process slower, but makes it harder to hack.