protected override ECPoint MultiplyPositive(ECPoint p, BigInteger k) { //IL_001c: Unknown result type (might be due to invalid IL or missing references) ECCurve curve = p.Curve; int combSize = FixedPointUtilities.GetCombSize(curve); if (k.BitLength > combSize) { throw new InvalidOperationException("fixed-point comb doesn't support scalars larger than the curve order"); } int widthForCombSize = GetWidthForCombSize(combSize); FixedPointPreCompInfo fixedPointPreCompInfo = FixedPointUtilities.Precompute(p, widthForCombSize); ECPoint[] preComp = fixedPointPreCompInfo.PreComp; int width = fixedPointPreCompInfo.Width; int num = (combSize + width - 1) / width; ECPoint eCPoint = curve.Infinity; int num2 = num * width - 1; for (int i = 0; i < num; i++) { int num3 = 0; for (int num4 = num2 - i; num4 >= 0; num4 -= num) { num3 <<= 1; if (k.TestBit(num4)) { num3 |= 1; } } eCPoint = eCPoint.TwicePlus(preComp[num3]); } return(eCPoint); }
protected override ECPoint MultiplyPositive(ECPoint p, BigInteger k) { ECCurve c = p.Curve; int combSize = FixedPointUtilities.GetCombSize(c); if (k.BitLength > combSize) { throw new InvalidOperationException("fixed-point comb doesn't support scalars larger than the curve order"); } int widthForCombSize = this.GetWidthForCombSize(combSize); FixedPointPreCompInfo info = FixedPointUtilities.Precompute(p, widthForCombSize); ECPoint[] preComp = info.PreComp; int width = info.Width; int num4 = ((combSize + width) - 1) / width; ECPoint infinity = c.Infinity; int num5 = (num4 * width) - 1; for (int i = 0; i < num4; i++) { int index = 0; for (int j = num5 - i; j >= 0; j -= num4) { index = index << 1; if (k.TestBit(j)) { index |= 1; } } infinity = infinity.TwicePlus(preComp[index]); } return(infinity); }
public PreCompInfo Precompute(PreCompInfo existing) { FixedPointPreCompInfo existingFP = (existing is FixedPointPreCompInfo) ? (FixedPointPreCompInfo)existing : null; ECCurve c = m_p.Curve; int bits = FixedPointUtilities.GetCombSize(c); int minWidth = bits > 250 ? 6 : 5; int n = 1 << minWidth; if (CheckExisting(existingFP, n)) { return(existingFP); } int d = (bits + minWidth - 1) / minWidth; ECPoint[] pow2Table = new ECPoint[minWidth + 1]; pow2Table[0] = m_p; for (int i = 1; i < minWidth; ++i) { pow2Table[i] = pow2Table[i - 1].TimesPow2(d); } // This will be the 'offset' value pow2Table[minWidth] = pow2Table[0].Subtract(pow2Table[1]); c.NormalizeAll(pow2Table); ECPoint[] lookupTable = new ECPoint[n]; lookupTable[0] = pow2Table[0]; 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); FixedPointPreCompInfo result = new FixedPointPreCompInfo(); result.LookupTable = c.CreateCacheSafeLookupTable(lookupTable, 0, lookupTable.Length); result.Offset = pow2Table[minWidth]; result.Width = minWidth; return(result); }
protected override ECPoint MultiplyPositive(ECPoint p, BigInteger k) { ECCurve c = p.Curve; int size = FixedPointUtilities.GetCombSize(c); if (k.BitLength > size) { /* * TODO The comb works best when the scalars are less than the (possibly unknown) order. * Still, if we want to handle larger scalars, we could allow customization of the comb * size, or alternatively we could deal with the 'extra' bits either by running the comb * multiple times as necessary, or by using an alternative multiplier as prelude. */ throw new InvalidOperationException("fixed-point comb doesn't support scalars larger than the curve order"); } FixedPointPreCompInfo info = FixedPointUtilities.Precompute(p); ECLookupTable lookupTable = info.LookupTable; int width = info.Width; int d = (size + width - 1) / width; ECPoint R = c.Infinity; int fullComb = d * width; uint[] K = Nat.FromBigInteger(fullComb, k); int top = fullComb - 1; for (int i = 0; i < d; ++i) { uint secretIndex = 0; for (int j = top - i; j >= 0; j -= d) { uint secretBit = K[j >> 5] >> (j & 0x1F); secretIndex ^= secretBit >> 1; secretIndex <<= 1; secretIndex ^= secretBit; } ECPoint add = lookupTable.Lookup((int)secretIndex); R = R.TwicePlus(add); } return(R.Add(info.Offset)); }
protected override ECPoint MultiplyPositive(ECPoint p, BigInteger k) { ECCurve c = p.Curve; int size = FixedPointUtilities.GetCombSize(c); if (k.BitLength > size) { /* * TODO The comb works best when the scalars are less than the (possibly unknown) order. * Still, if we want to handle larger scalars, we could allow customization of the comb * size, or alternatively we could deal with the 'extra' bits either by running the comb * multiple times as necessary, or by using an alternative multiplier as prelude. */ throw new InvalidOperationException("fixed-point comb doesn't support scalars larger than the curve order"); } // TODO Call method to let subclasses select width int width = size > 257 ? 6 : 5; FixedPointPreCompInfo info = FixedPointUtilities.Precompute(p, width); ECPoint[] lookupTable = info.PreComp; int d = (size + width - 1) / width; ECPoint R = c.Infinity; int top = d * width - 1; for (int i = 0; i < d; ++i) { int index = 0; for (int j = top - i; j >= 0; j -= d) { index <<= 1; if (k.TestBit(j)) { index |= 1; } } R = R.TwicePlus(lookupTable[index]); } return(R); }
public static FixedPointPreCompInfo Precompute(ECPoint p, int minWidth) { ECCurve curve = p.Curve; int num = 1 << minWidth; FixedPointPreCompInfo fixedPointPreCompInfo = FixedPointUtilities.GetFixedPointPreCompInfo(curve.GetPreCompInfo(p, FixedPointUtilities.PRECOMP_NAME)); ECPoint[] array = fixedPointPreCompInfo.PreComp; if (array == null || array.Length < num) { int combSize = FixedPointUtilities.GetCombSize(curve); int e = (combSize + minWidth - 1) / minWidth; ECPoint[] array2 = new ECPoint[minWidth]; array2[0] = p; for (int i = 1; i < minWidth; i++) { array2[i] = array2[i - 1].TimesPow2(e); } curve.NormalizeAll(array2); array = new ECPoint[num]; array[0] = curve.Infinity; for (int j = minWidth - 1; j >= 0; j--) { ECPoint b = array2[j]; int num2 = 1 << j; for (int k = num2; k < num; k += num2 << 1) { array[k] = array[k - num2].Add(b); } } curve.NormalizeAll(array); fixedPointPreCompInfo.PreComp = array; fixedPointPreCompInfo.Width = minWidth; curve.SetPreCompInfo(p, FixedPointUtilities.PRECOMP_NAME, fixedPointPreCompInfo); } return(fixedPointPreCompInfo); }