Abstract: Playfair cipher is the first known digraph polyalphabetic method. It relies on 5x5 uppercase alphabets matrix with simple substitution processes to be used for encryption and decryption. This paper proposes an enhanced variant of Playfair cipher algorithm that incorporates an algorithm for elaborate key generation starting with a seed accompanying the ciphertext and will be referred to as a Novel Paradigm for Symmetric Cryptosystem (NPSC). The key generation, encryption and decryption processes implement modular calculations instead of the simple substitution used in the traditional Playfair cipher. It supports both alphabetic characters and numerals. This variant considerably enhances the security strength without increasing the matrix size as demonstrated by the experimentation results. Comparative studies of various critical factors with other reported versions of Playfair cipher and results were also included.

Shadi R. Masadeh, Hamza A. Al_Sewadi and Mohammad A. Wadi, “A Novel Paradigm for Symmetric Cryptosystem” International Journal of Advanced Computer Science and Applications(IJACSA), 7(3), 2016. http://dx.doi.org/10.14569/IJACSA.2016.070317

@article{Masadeh2016,
title = {A Novel Paradigm for Symmetric Cryptosystem},
journal = {International Journal of Advanced Computer Science and Applications},
doi = {10.14569/IJACSA.2016.070317},
url = {http://dx.doi.org/10.14569/IJACSA.2016.070317},
year = {2016},
publisher = {The Science and Information Organization},
volume = {7},
number = {3},
author = {Shadi R. Masadeh and Hamza A. Al_Sewadi and Mohammad A. Wadi}
}