Fast construction of binary ring FCSRs for hardware stream ciphers

Abstract

Stream ciphers based on linear feedback shift registers have been subject to algebraic attacks. To avoid these kinds of attacks, feedback with carry shift registers (FCSRs) have been proposed as an alternative. They are suitable for hardware implementations. FCSRs have been implemented using ring representation, in order to circumvent some weaknesses in the traditional representations. In this paper, we explore the simplest case of FCSRs, called binary FCSRs, which are common in applications. We give a fast algorithm to construct binary ring FCSRs for hardware stream ciphers.