Modified Alternating Step Generators with Non-Linear Scrambler

Abstract

Pseudorandom generators, which produce keystreams for stream ciphers by the exclusiveor sum of outputs of alternately clocked linear feedback shift registers, are vulnerable to cryptanalysis.In order to increase their resistance to attacks, we introduce a non-linear scrambler at the output of these generators. Non-linear feedback shift register plays the role of the scrambler. In addition, we propose Modified Alternating Step Generator with a non-linear scrambler (MASG 1S ) built with non-linear feedback shift register and regularly or irregularly clocked linear feedback shift registers with non-linear filtering functions.

Searching for nonlinear feedback shift registers with parallel computing

“…The investigations from the previous paper [12] have also been continued using the Field Programmable Gate Arrays to find maximum period NLFSRs. Nonlinear feedback shift registers have been applied in [13] to construct modified alternating step generators.…”