## A HYBRID COMBINATION OF SUBSTITUTION AND TRANSPOSITION CIPHERS FOR EFFICIENT ENCRYPTION USING GRAPH LABELING

## A HYBRID COMBINATION OF SUBSTITUTION AND TRANSPOSITION CIPHERS FOR EFFICIENT ENCRYPTION USING GRAPH LABELING

*V. N. J. Shruthy, V. Maheswari*

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## Abstract

In this study, we conceptualise a hybrid approach of plaintext encryption by making use of Substitution and Transposition cipher technique namely Playfair Cipher and Simple Columnar Transposition. Both the Ciphers are Symmetric Encryption Tech- nique and the need for developing such a hybrid is to inherit the positive traits as well as restrict certain limitations of both the techniques to a considerable extent. The resulting hybrid text is further subjected to Graph Labeling Technique as the receiver receives the ciphertext in the form of a Graph structure together with a clue to determine the type of labeling used and the ciphertext sequence. Here we adopt two varied labeling techniques namely Simply Sequentially Additive labeling and Distance two labeling for some Tree related Graphs and the corresponding Decryption of the Cipher Graph yields the desired plaintext.

## Keywords

Playfair Cipher, Simple Columnar transposition, Hybrid text, Simply Se- quentially Additive labeling, Distance Two labeling, Cipher Graph.