Modified version of playfair technique to enhance the security of plaintext and key using rectangular and substitution matrix

Abstract

To make the data more secure there are several techniques. Most of the techniques have modified many times. Most authors used those modified techniques in their algorithm. Playfair technique is one of them. Playfair technique has also modified several time. Most authors used 6*6 matrix which include alphabets in lowercase, integer value as well as special symbols, most 7*7 matrix which include alphabets in uppercase and in lower case both, integer value as well as special symbols. We used 9*9 matrix which includes alphabets in lowercase or in uppercase both, integer value as well as list of operators and putting in the matrix according to their value in ASCII code. ASCII code stands for American Standard Code for Information Interchange. This work uses ASCII code to provide more security. For dual security, a substitution matrix is also used so that no one can understand it easily, even decoder have to do more and more efforts for decrypting the cipher text. Hence with the help of this technique we make our data safe.