Clock-Controlled Shrinking Generator of Feedback Shift Registers

Abstract

A system related to the shrinking generator that is made up of two feedback shift registers in which one (FSR $\mathbb{A}$)) controls the clocking of the other (FSR $\mathbb{B}$) is introduced. It is established that if FSR $\mathbb{A}$) generates an m-sequence of period (2^m − 1) and FSR $\mathbb{B}$ generates a de Bruijn sequence of period 2^η, then the output sequence of the system has period P = 2^m+ν−1, linear complexity L bounded from below by 2^m+η−2, good statistical properties, and it is secure against correlation attacks. All these properties make it a suitable crypto-generator for stream cipher applications.