An Approach Towards Modification of Playfair Cipher Using 16 \(\times \) 16 Matrix

The Play fair cipher is a popular polyalphabetic encryption. It mathematically secures information by encrypting the message with a key. The same key is used to change cipher text digraphs into plain text digraphs during decryption. However, only 25 alphabets can be supported by the original 5 \(\times \) 5 play fair cipher. To overcome the limitation, different types of modifications were proposed in the traditional Playfair cipher. But still, it was at the receiving end of successful attacks due to the limitations. In this paper, the proposed method circumvents the limitations of past studies that used a play fair cipher using a 5 \(\times \) 5 matrix, 7 \(\times \) 4 matrix, and 6 \(\times \) 6 matrix. The suggested technique utilizes a 16 \(\times \) 16 matrix and provides strength for Playfair cipher. The proposed work is an improvement to the original structure that makes use of matrix rolling, shifting, and rotation to improve security. It uses alphabets, both lowercase and uppercase letters, numbers, and special characters to build the matrix’s content.