On Analysis and Synthesis of (n, k)-Non-Linear Feedback Shift Registers

— Non-Linear Feedback Shift Registers (NLFSRs) have been proposed as an alternative to Linear Feedback Shift Registers (LFSRs) for generating pseudo-random sequences for stream ciphers. In this paper, we introduce (n,k)-NLFSRs which can be considered a generalization of the Galois type of LFSR. In an (n,k)-NLFSR, the feedback can be taken from any of the n bits, and the next state functions can be any Boolean function of up to k variables. Our motivation for considering this type NLFSRs is that their Galois configuration makes it possible to compute each next state function in parallel, thus increasing the speed of output sequence generation. Thus, for stream cipher application where the encryption speed is important, (n,k)-NLFSRs may be a better alternative than the traditional Fibonacci ones. We derive a number of properties of (n,k)NLFSRs. First, we demonstrate that they are capable of generating output sequences with good statistical properties which cannot be generated by the F...

• Type: Conference
• Year: 2008
• Where: DATE
• Authors: Elena Dubrova, Maxim Teslenko, Hannu Tenhunen
• Keywords: DATE 2008, Feedback Shift Registers, Hardware, Linear Feedback Shift Registers, Output Sequence