Nonlinear-feedback shift register

A nonlinear-feedback shift register (NLFSR) is a shift register whose input bit is a non-linear function of its previous state. For an n-bit shift register r its next state is defined as: r i + 1 ( b 0 , b 1 , b 2 , … , b n − 1 ) = r i ( b 1 , b 2 , … , f ( b 0 , b 1 , b 2 , … , b n − 1 ) ) {\displaystyle r_{i+1}(b_{0},b_{1},b_{2},\ldots ,b_{n-1})=r_{i}(b_{1},b_{2},\ldots ,f(b_{0},b_{1},b_{2},\ldots ,b_{n-1}))} , where f is the non-linear feedback function.

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