Design of Modified Exclusive-128 Bit NLFSR Stream Cipher and Randomness Test

Abstract

In this paper, we describe modified Exclusive-128 NLFSR stream cipher which generates 128 bit keystreams using only NLFSR element as its main function and XOR operation. It consists of different sizes of NLFSRs both in Fibonacci and Galois configurations which offer better trade off between the algorithm security and hardware capability. Further, using this modified version of Exclusive-128 NLFSR stream cipher, analysis has been done for pseudorandom test to prove that this stream cipher is highly non-linear and truly randomness when all the initial key inputs are either zero and/or one. Keyword Cryptography, Stream cipher, NLFSR, Fibonacci configuration, Galois configuration, NIST Randomness Test.