Algebraic Attack on Filter-Combiner Model Keystream Generators

摘要

Algebraic attack was applied to attack Filter-Combiner model keystream generators. We proposed the technique of function composition to improve the model, and the improved model can resist the algebraic attack. A new criterion for designing Filter-Combiner model was also proposed: the total length L of Linear Finite State Machines used in the model should be large enough and the degree d of Filter-Combiner function should be approximate L/2.