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