77 lines
2.3 KiB
C#
77 lines
2.3 KiB
C#
|
#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
|
||
|
|
|
||
|
|
using System;
|
||
|
|
|
||
|
|
namespace Org.BouncyCastle.Math.EC.Multiplier
|
||
|
|
{
|
||
|
|
public class FixedPointUtilities
|
||
|
|
{
|
||
|
|
public static readonly string PRECOMP_NAME = "bc_fixed_point";
|
||
|
|
|
||
|
|
public static int GetCombSize(ECCurve c)
|
||
|
|
{
|
||
|
|
BigInteger order = c.Order;
|
||
|
|
return order == null ? c.FieldSize + 1 : order.BitLength;
|
||
|
|
}
|
||
|
|
|
||
|
|
public static FixedPointPreCompInfo GetFixedPointPreCompInfo(PreCompInfo preCompInfo)
|
||
|
|
{
|
||
|
|
if ((preCompInfo != null) && (preCompInfo is FixedPointPreCompInfo))
|
||
|
|
{
|
||
|
|
return (FixedPointPreCompInfo)preCompInfo;
|
||
|
|
}
|
||
|
|
|
||
|
|
return new FixedPointPreCompInfo();
|
||
|
|
}
|
||
|
|
|
||
|
|
public static FixedPointPreCompInfo Precompute(ECPoint p, int minWidth)
|
||
|
|
{
|
||
|
|
ECCurve c = p.Curve;
|
||
|
|
|
||
|
|
int n = 1 << minWidth;
|
||
|
|
FixedPointPreCompInfo info = GetFixedPointPreCompInfo(c.GetPreCompInfo(p, PRECOMP_NAME));
|
||
|
|
ECPoint[] lookupTable = info.PreComp;
|
||
|
|
|
||
|
|
if (lookupTable == null || lookupTable.Length < n)
|
||
|
|
{
|
||
|
|
int bits = GetCombSize(c);
|
||
|
|
int d = (bits + minWidth - 1) / minWidth;
|
||
|
|
|
||
|
|
ECPoint[] pow2Table = new ECPoint[minWidth];
|
||
|
|
pow2Table[0] = p;
|
||
|
|
for (int i = 1; i < minWidth; ++i)
|
||
|
|
{
|
||
|
|
pow2Table[i] = pow2Table[i - 1].TimesPow2(d);
|
||
|
|
}
|
||
|
|
|
||
|
|
c.NormalizeAll(pow2Table);
|
||
|
|
|
||
|
|
lookupTable = new ECPoint[n];
|
||
|
|
lookupTable[0] = c.Infinity;
|
||
|
|
|
||
|
|
for (int bit = minWidth - 1; bit >= 0; --bit)
|
||
|
|
{
|
||
|
|
ECPoint pow2 = pow2Table[bit];
|
||
|
|
|
||
|
|
int step = 1 << bit;
|
||
|
|
for (int i = step; i < n; i += (step << 1))
|
||
|
|
{
|
||
|
|
lookupTable[i] = lookupTable[i - step].Add(pow2);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
c.NormalizeAll(lookupTable);
|
||
|
|
|
||
|
|
info.PreComp = lookupTable;
|
||
|
|
info.Width = minWidth;
|
||
|
|
|
||
|
|
c.SetPreCompInfo(p, PRECOMP_NAME, info);
|
||
|
|
}
|
||
|
|
|
||
|
|
return info;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif
|