A new modified playfair cipher

The methods of encryption and decryption are used to protect the transferred information through public channels. The symmetric cipher methods that are based on the shared secrecy are preferable for this purpose. Playfair cipher is one of the classical symmetric ciphers; it has some limitation because it uses 5×5 matrix. To overcome this limitation, we propose in this paper a new encryption and decryption method based on the classical playfair cipher by expanding it to an n×n matrix with permutation and transposition. The security and the efficiency of the proposed method are demonstrated in comparing to the traditional and other modified playfair ciphers.