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JOURNALS // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika // Archive

Vestnik Moskov. Univ. Ser. 1. Mat. Mekh., 2021 Number 3, Pages 22–31 (Mi vmumm4399)

Mathematics

Fast algorithms for solving equations of degree $\le4$ in some finite fields

S. B. Gashkov

Lomonosov Moscow State University, Faculty of Mechanics and Mathematics

Abstract: It is possible to solve equations of degree $\leq 4$ in some bases of the field $GF(p^s),$ where $p>3,$ $s = 2^kr,$ $k \rightarrow \infty,$ $r=\pm 1 \pmod 6,$ $p,r=O(1)$, with the bit complexity
$$ O_r(M(2^k)kM(r)M(\lceil \log_2p)\rceil)= O_{r,p}(M(s)\log_2s), $$
where $M(n)$ is the complexity of polynomial multiplication. In a normal basis of the fields $GF(3^s),$ $s=\pm 1 \pmod 6,$ all roots may be found with the bit complexity $O(M(GF(3^s))\log_2s),$ where $M(GF(q))$ is the complexity of multiplication in the field $GF(q).$ For normal bases in the fields $GF(2^s),$ where $s = 2r,$ $r \neq 0 \pmod 3,$ the bit complexity is $O(M(GF(2^s))\log_2s).$

Key words: solving equations, bit complexity, tower of finite fields, standard and normal bases.

UDC: 511

Received: 11.09.2020


 English version:
Moscow University Mathematics Bulletin, Moscow University Måchanics Bulletin, 2021, 76:3, 107–117

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© Steklov Math. Inst. of RAS, 2026