Analysis a Class of Stream Ciphers

Abstract

Stream cipher systems are widely used in secure sensitive information cryptography, since they are fast and lower error propogation. The designing of some of these systems depend on using more than one LFSRs with different length and combined function with different feedback polynomials. They are varing in security. This paper produces an anaysis about the standards to be considered in designing the LFSRs stream cipher systems that concerned in choosing shift registers and their linear complexity. Also it produces a method that is used to attack this class of stream cipher systems.