International Association
for Cryptologic Research

Designing a keystream generator which utilizes Linear Feedback

Shift Registers (LFSRs) against correlation, linear attacks is a highly

challenging task. In this paper, a new framework for keystream generators is proposed. It is comprised of a set of Linear Feedback Shift Registers (LFSRs), a Multiplicative Congruential Generator (MCG),

a vector linear function and, a Boolean function which outputs the

keystream. The framework is more generally discussed against

correlation attacks, linear attacks and distinguishing (linear) attacks. It is shown that such attacks which are applicable to LFSR based keystream generators are not possible on the proposed framework.