Study of NLFSR and Reasonable Security Improvement on Trivium Cipher

The decision regarding widely acceptable stream cipher for hardware security is one of the challenging assignment. Trivium cipher is ironed out most of the weakness of the other stream ciphers. Beside this, our paper presents the security analysis of Trivium and some modification of cipher which gives better security level. Our primary focus is finding some particular biases of output and reasonable algebraic attack with some guessing approach. More specifically, we show some modifications which can increase its security level without changing its internal structure. For this cipher finally we obtain some new cryptanalytic result and the next part of the paper we study some algebraic analysis of Trivium cipher and we try to show that it is vulnerable to different types of attacks and try to recover the overall internal state of the stream cipher.