Novel Approach Transforming Stream Cipher to Block Cipher

Abstract

In the current time of web, when user establish the communication with another party and user want to share some secrete documents or information in the presence of third party, user need some technique to secure the data from that third party. To protect their data, users are using many methods and day by day improved versions of these methods are coming. At the same time attackers are using new methods to break these new security methods/techniques. A novel approach of providing security to sender & receiver in protecting the data from attackers has been discussed in this article. The proposed approach converts the basic 5x5 play fair stream cipher into the block cipher. Proposed approach is a two-step symmetric key algorithm. First step takes traditional play fair 5x5 matrix of 26 characters and second step takes 25 matrix of (5x5) size having 625 words. So as to change plain content into cipher content first of all see the plain text pair in the first matrix according the position of these characters replace the words from the second matrix by following all rules of traditional play fair algorithm. At the end, a comparative analysis of strength of proposed algorithm has been done with other algorithms.