Optimization and analysis of the extended Playfair cipher

The well known multiple letter encryption cipher is the Playfair cipher. Here the diagrams in the plaintext are treated as single units and converted into corresponding cipher text diagrams. However because of the drawbacks inherent in the 5*5 Playfair cipher which adversely affects the security we proposed an 8*8 Playfair cipher. For details one can refer to [1]. This paper analyses the new proposed system. For this we have carried out cryptanalysis and through the avalanche effect we find out that the proposed cipher is a strong one.