Function isSquare [src]

Return true if the field element is a square

Prototype

pub fn isSquare(a: Fe) bool

Parameters

a: Fe

Source

  pub fn isSquare(a: Fe) bool {
    // Compute the Jacobi symbol x^((p-1)/2)
    const _11 = a.mul(a.sq());
    const _1111 = _11.mul(_11.sq().sq());
    const _11111111 = _1111.mul(_1111.sq().sq().sq().sq());
    const u = _11111111.sqn(2).mul(_11);
    const t = u.sqn(10).mul(u).sqn(10).mul(u);
    const t2 = t.sqn(30).mul(t);
    const t3 = t2.sqn(60).mul(t2);
    const t4 = t3.sqn(120).mul(t3).sqn(10).mul(u).sqn(3).mul(_11).sq();
    return @as(bool, @bitCast(@as(u1, @truncate(~(t4.toBytes()[1] & 1)))));
}  