[Resource Topic] 2012/112: On The Nonlinearity of Maximum-length NFSR Feedbacks

Welcome to the resource topic for 2012/112

Title:
On The Nonlinearity of Maximum-length NFSR Feedbacks

Authors: Meltem Sonmez Turan

Abstract:

Linear Feedback Shift Registers (LFSRs) are the main building block of many classical stream ciphers; however due to their inherent linearity, most of the LFSR-based designs do not offer the desired security levels. In the last decade, using Nonlinear Feedback Shift Registers(NFSRs) in stream ciphers became very popular. However, the theory of NFSRs is not well-understood, and there is no efficient method that constructs a cryptographically strong feedback function with maximum period and also, given a feedback function it is hard to predict the period. In this paper, we study the maximum-length NFSRs, focusing on the nonlinearity of their feedback functions. First, we provide some upper bounds on the nonlinearity of the maximum-length feedback functions, and then we study the feedback functions having nonlinearity 2 in detail. We also show some techniques to improve the nonlinearity of a given feedback function using cross-joining.

ePrint: https://eprint.iacr.org/2012/112

See all topics related to this paper.

Feel free to post resources that are related to this paper below.

Example resources include: implementations, explanation materials, talks, slides, links to previous discussions on other websites.

For more information, see the rules for Resource Topics .