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Computes the Ed25519 Base lookup table
private static void ge_cached_to_precomp(out GroupElementPreComp preComp, ref GroupElementCached cached)
{
FieldElement invDenominator;
FieldOperations.fe_invert(out invDenominator, ref cached.Z);
FieldOperations.fe_mul(out preComp.yminusx, ref cached.YminusX, ref invDenominator);
FieldOperations.fe_mul(out preComp.yplusx, ref cached.YplusX, ref invDenominator);
FieldOperations.fe_mul(out preComp.xy2d, ref cached.T2d, ref invDenominator);
}
private static GroupElementPreComp[] ComputeLine(ref GroupElementCached b)
{
var result = new GroupElementPreComp[8];
GroupElementP3 p3;
GroupOperations.ge_p3_0(out p3);
for (int j = 0; j < 8; j++)
{
GroupElementP1P1 p1p1;
GroupElementCached cached;
GroupOperations.ge_add(out p1p1, ref p3, ref b);
GroupOperations.ge_p1p1_to_p3(out p3, ref p1p1);
GroupOperations.ge_p3_to_cached(out cached, ref p3);
ge_cached_to_precomp(out result[j], ref cached);
}
return result;
}
internal static GroupElementPreComp[][] ComputeTable(ref GroupElementCached b)
{
var result = new GroupElementPreComp[32][];
GroupElementP3 p3;
GroupElementP2 p2;
GroupElementP1P1 p1p1;
GroupElementCached cached;
GroupOperations.ge_p3_0(out p3);
GroupOperations.ge_add(out p1p1, ref p3, ref b);
GroupOperations.ge_p1p1_to_p3(out p3, ref p1p1);
for (int i = 0; i < 32; i++)
{
GroupOperations.ge_p3_to_cached(out cached, ref p3);
result[i] = ComputeLine(ref cached);
GroupOperations.ge_p3_to_p2(out p2, ref p3);
for (int k = 0; k < 7; k++)
{
GroupOperations.ge_p2_dbl(out p1p1, ref p2);
GroupOperations.ge_p1p1_to_p2(out p2, ref p1p1);
}
GroupOperations.ge_p2_dbl(out p1p1, ref p2);
GroupOperations.ge_p1p1_to_p3(out p3, ref p1p1);
}
return result;
}
internal static GroupElementPreComp[][] ComputeTable()
{
GroupElementCached cached;
cached.YplusX = new FieldElement(25967493, -14356035, 29566456, 3660896, -12694345, 4014787, 27544626, -11754271, -6079156, 2047605);
cached.YminusX = new FieldElement(-12545711, 934262, -2722910, 3049990, -727428, 9406986, 12720692, 5043384, 19500929, -15469378);
cached.T2d = new FieldElement(-8738181, 4489570, 9688441, -14785194, 10184609, -12363380, 29287919, 11864899, -24514362, -4438546);
FieldOperations.fe_1(out cached.Z);
var result = ComputeTable(ref cached);
return result;
}
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