Secure Key Exchange using RSA in Extended Playfair Cipher Technique

Abstract

In today’s digital world cryptography is used to secure information in order to provide the privacy for the intended sender and receiver by managing the message with the public key. The objective of this work is to securing the key of Playfair cipher using RSA algorithm. It is a two stage application, in first stage the existing methods of Playfair cipher modified by increasing in the size of matrix, so that the restrictions of earlier works of PF cipher using 5×5 matrix were overcome in the proposed work. The proposed method use a 12×8 matrix which contain all alphabetic, numeric and special character use in keyboard as input. This work is an enhancement to the existing algorithms that uses 5×5 matrix to pick cipher characters. It makes use of alphabets both lower and upper case characters, number and special characters for constructing the contents of the matrix. In the second stage, RSA public key encryption technique is used for sending the key of the PF ciphers securely. Finally, the security strength of the whole system has been analyzed and tried to fulfil the requirement of security.