Research on reconfigurable nonlinear Boolean functions hardware structure targeted at stream cipher

Abstract

Based on the characteristics of the nonlinear Boolean functions operated in stream ciphers, a reconfigurable hardware architecture for these nonlinear Boolean functions is presented, which could be reconfigured many different structures to match for the functions, such as the nonlinear Feedback functions of shift registers and the nonlinear filtering functions. The architecture in this design has been realized using Altera's FPGA. Synthesis, placement and routing of reconfigurable design have accomplished on 0.18µm COMS process. The result proves that the design is propitious to carry out the most nonlinear Boolean functions in stream ciphers which have been published. A nonlinear function of 128 variables, the propagation time is 2.84ns, compared with other designs, the structure can achieve relatively high flexibility, and it has an obvious advantage in the area of circuit and the aspect of speed.1