Patent ID: 6266688
Filing Date: 2001-07-24
Classification: G06F

Abstract:
A method for calculating a square in finite field GF(2.sup.2n), comprising the steps of:expressing an element m.di-elect cons.GF(2.sup.2n).congruent.GF(2.sup.n)[x]/(x.sup.2 +x+a) asm=x+y.alpha.(x, y.di-elect cons.GF(2.sup.n))where .alpha..epsilon slash.GF(2.sup.n), .alpha..sup.2 +.alpha.+a=0, and a.di-elect cons.GF(2.sup.n) so that a square m.sup.2 of the element m in the finite field GF(2.sup.2n) is expressed as a combination of multiplications and additions in subfield GF(2.sup.n) given bym.sup.2 =(x.sup.2 +ay.sup.2)+y.sup.2.alpha.by using a standard basis [1 .alpha.]; andcalculating the square m.sup.2 of the element m in the finite field GF(2.sup.2n) by executing said combination of multiplications and additions in the subfield GF(2.sup.n).