diff options
Diffstat (limited to 'crypto/src/math/ec/multiplier/WNafUtilities.cs')
| -rw-r--r-- | crypto/src/math/ec/multiplier/WNafUtilities.cs | 311 |
1 files changed, 183 insertions, 128 deletions
diff --git a/crypto/src/math/ec/multiplier/WNafUtilities.cs b/crypto/src/math/ec/multiplier/WNafUtilities.cs index 7d565dfbd..e893abd49 100644 --- a/crypto/src/math/ec/multiplier/WNafUtilities.cs +++ b/crypto/src/math/ec/multiplier/WNafUtilities.cs @@ -287,12 +287,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier public static WNafPreCompInfo GetWNafPreCompInfo(PreCompInfo preCompInfo) { - if ((preCompInfo != null) && (preCompInfo is WNafPreCompInfo)) - { - return (WNafPreCompInfo)preCompInfo; - } - - return new WNafPreCompInfo(); + return preCompInfo as WNafPreCompInfo; } /** @@ -333,106 +328,178 @@ namespace Org.BouncyCastle.Math.EC.Multiplier WNafPreCompInfo wnafPreCompP = Precompute(p, width, includeNegated); ECPoint q = pointMap.Map(p); - WNafPreCompInfo wnafPreCompQ = GetWNafPreCompInfo(c.GetPreCompInfo(q, PRECOMP_NAME)); + c.Precompute(q, PRECOMP_NAME, new MapPointCallback(wnafPreCompP, includeNegated, pointMap)); + return q; + } - ECPoint twiceP = wnafPreCompP.Twice; - if (twiceP != null) - { - ECPoint twiceQ = pointMap.Map(twiceP); - wnafPreCompQ.Twice = twiceQ; - } + public static WNafPreCompInfo Precompute(ECPoint p, int width, bool includeNegated) + { + return (WNafPreCompInfo)p.Curve.Precompute(p, PRECOMP_NAME, new WNafCallback(p, width, includeNegated)); + } + + private static byte[] Trim(byte[] a, int length) + { + byte[] result = new byte[length]; + Array.Copy(a, 0, result, 0, result.Length); + return result; + } + + private static int[] Trim(int[] a, int length) + { + int[] result = new int[length]; + Array.Copy(a, 0, result, 0, result.Length); + return result; + } + + private static ECPoint[] ResizeTable(ECPoint[] a, int length) + { + ECPoint[] result = new ECPoint[length]; + Array.Copy(a, 0, result, 0, a.Length); + return result; + } + + private class MapPointCallback + : IPreCompCallback + { + private readonly WNafPreCompInfo m_wnafPreCompP; + private readonly bool m_includeNegated; + private readonly ECPointMap m_pointMap; - ECPoint[] preCompP = wnafPreCompP.PreComp; - ECPoint[] preCompQ = new ECPoint[preCompP.Length]; - for (int i = 0; i < preCompP.Length; ++i) + internal MapPointCallback(WNafPreCompInfo wnafPreCompP, bool includeNegated, ECPointMap pointMap) { - preCompQ[i] = pointMap.Map(preCompP[i]); + this.m_wnafPreCompP = wnafPreCompP; + this.m_includeNegated = includeNegated; + this.m_pointMap = pointMap; } - wnafPreCompQ.PreComp = preCompQ; - if (includeNegated) + public PreCompInfo Precompute(PreCompInfo existing) { - ECPoint[] preCompNegQ = new ECPoint[preCompQ.Length]; - for (int i = 0; i < preCompNegQ.Length; ++i) + WNafPreCompInfo result = new WNafPreCompInfo(); + + ECPoint twiceP = m_wnafPreCompP.Twice; + if (twiceP != null) { - preCompNegQ[i] = preCompQ[i].Negate(); + ECPoint twiceQ = m_pointMap.Map(twiceP); + result.Twice = twiceQ; } - wnafPreCompQ.PreCompNeg = preCompNegQ; - } - c.SetPreCompInfo(q, PRECOMP_NAME, wnafPreCompQ); + ECPoint[] preCompP = m_wnafPreCompP.PreComp; + ECPoint[] preCompQ = new ECPoint[preCompP.Length]; + for (int i = 0; i < preCompP.Length; ++i) + { + preCompQ[i] = m_pointMap.Map(preCompP[i]); + } + result.PreComp = preCompQ; - return q; + if (m_includeNegated) + { + ECPoint[] preCompNegQ = new ECPoint[preCompQ.Length]; + for (int i = 0; i < preCompNegQ.Length; ++i) + { + preCompNegQ[i] = preCompQ[i].Negate(); + } + result.PreCompNeg = preCompNegQ; + } + + return result; + } } - public static WNafPreCompInfo Precompute(ECPoint p, int width, bool includeNegated) + private class WNafCallback + : IPreCompCallback { - ECCurve c = p.Curve; - WNafPreCompInfo wnafPreCompInfo = GetWNafPreCompInfo(c.GetPreCompInfo(p, PRECOMP_NAME)); + private readonly ECPoint m_p; + private readonly int m_width; + private readonly bool m_includeNegated; - int iniPreCompLen = 0, reqPreCompLen = 1 << System.Math.Max(0, width - 2); - - ECPoint[] preComp = wnafPreCompInfo.PreComp; - if (preComp == null) + internal WNafCallback(ECPoint p, int width, bool includeNegated) { - preComp = EMPTY_POINTS; - } - else - { - iniPreCompLen = preComp.Length; + this.m_p = p; + this.m_width = width; + this.m_includeNegated = includeNegated; } - if (iniPreCompLen < reqPreCompLen) + public PreCompInfo Precompute(PreCompInfo existing) { - preComp = ResizeTable(preComp, reqPreCompLen); + WNafPreCompInfo existingWNaf = existing as WNafPreCompInfo; + + int reqPreCompLen = 1 << System.Math.Max(0, m_width - 2); + + if (CheckExisting(existingWNaf, reqPreCompLen, m_includeNegated)) + return existingWNaf; - if (reqPreCompLen == 1) + ECCurve c = m_p.Curve; + ECPoint[] preComp = null, preCompNeg = null; + ECPoint twiceP = null; + + if (existingWNaf != null) + { + preComp = existingWNaf.PreComp; + preCompNeg = existingWNaf.PreCompNeg; + twiceP = existingWNaf.Twice; + } + + int iniPreCompLen = 0; + if (preComp == null) { - preComp[0] = p.Normalize(); + preComp = EMPTY_POINTS; } else { - int curPreCompLen = iniPreCompLen; - if (curPreCompLen == 0) - { - preComp[0] = p; - curPreCompLen = 1; - } + iniPreCompLen = preComp.Length; + } - ECFieldElement iso = null; + if (iniPreCompLen < reqPreCompLen) + { + preComp = WNafUtilities.ResizeTable(preComp, reqPreCompLen); - if (reqPreCompLen == 2) + if (reqPreCompLen == 1) { - preComp[1] = p.ThreeTimes(); + preComp[0] = m_p.Normalize(); } else { - ECPoint twiceP = wnafPreCompInfo.Twice, last = preComp[curPreCompLen - 1]; - if (twiceP == null) + int curPreCompLen = iniPreCompLen; + if (curPreCompLen == 0) + { + preComp[0] = m_p; + curPreCompLen = 1; + } + + ECFieldElement iso = null; + + if (reqPreCompLen == 2) + { + preComp[1] = m_p.ThreeTimes(); + } + else { - twiceP = preComp[0].Twice(); - wnafPreCompInfo.Twice = twiceP; - - /* - * For Fp curves with Jacobian projective coordinates, use a (quasi-)isomorphism - * where 'twiceP' is "affine", so that the subsequent additions are cheaper. This - * also requires scaling the initial point's X, Y coordinates, and reversing the - * isomorphism as part of the subsequent normalization. - * - * NOTE: The correctness of this optimization depends on: - * 1) additions do not use the curve's A, B coefficients. - * 2) no special cases (i.e. Q +/- Q) when calculating 1P, 3P, 5P, ... - */ - if (!twiceP.IsInfinity && ECAlgorithms.IsFpCurve(c) && c.FieldSize >= 64) + ECPoint isoTwiceP = twiceP, last = preComp[curPreCompLen - 1]; + if (isoTwiceP == null) { - switch (c.CoordinateSystem) + isoTwiceP = preComp[0].Twice(); + twiceP = isoTwiceP; + + /* + * For Fp curves with Jacobian projective coordinates, use a (quasi-)isomorphism + * where 'twiceP' is "affine", so that the subsequent additions are cheaper. This + * also requires scaling the initial point's X, Y coordinates, and reversing the + * isomorphism as part of the subsequent normalization. + * + * NOTE: The correctness of this optimization depends on: + * 1) additions do not use the curve's A, B coefficients. + * 2) no special cases (i.e. Q +/- Q) when calculating 1P, 3P, 5P, ... + */ + if (!twiceP.IsInfinity && ECAlgorithms.IsFpCurve(c) && c.FieldSize >= 64) { + switch (c.CoordinateSystem) + { case ECCurve.COORD_JACOBIAN: case ECCurve.COORD_JACOBIAN_CHUDNOVSKY: case ECCurve.COORD_JACOBIAN_MODIFIED: { iso = twiceP.GetZCoord(0); - twiceP = c.CreatePoint(twiceP.XCoord.ToBigInteger(), + isoTwiceP = c.CreatePoint(twiceP.XCoord.ToBigInteger(), twiceP.YCoord.ToBigInteger()); ECFieldElement iso2 = iso.Square(), iso3 = iso2.Multiply(iso); @@ -444,81 +511,69 @@ namespace Org.BouncyCastle.Math.EC.Multiplier } break; } + } } } - } - while (curPreCompLen < reqPreCompLen) - { - /* - * Compute the new ECPoints for the precomputation array. The values 1, 3, - * 5, ..., 2^(width-1)-1 times p are computed - */ - preComp[curPreCompLen++] = last = last.Add(twiceP); + while (curPreCompLen < reqPreCompLen) + { + /* + * Compute the new ECPoints for the precomputation array. The values 1, 3, + * 5, ..., 2^(width-1)-1 times p are computed + */ + preComp[curPreCompLen++] = last = last.Add(isoTwiceP); + } } - } - /* - * Having oft-used operands in affine form makes operations faster. - */ - c.NormalizeAll(preComp, iniPreCompLen, reqPreCompLen - iniPreCompLen, iso); + /* + * Having oft-used operands in affine form makes operations faster. + */ + c.NormalizeAll(preComp, iniPreCompLen, reqPreCompLen - iniPreCompLen, iso); + } } - } - - wnafPreCompInfo.PreComp = preComp; - - if (includeNegated) - { - ECPoint[] preCompNeg = wnafPreCompInfo.PreCompNeg; - int pos; - if (preCompNeg == null) - { - pos = 0; - preCompNeg = new ECPoint[reqPreCompLen]; - } - else + if (m_includeNegated) { - pos = preCompNeg.Length; - if (pos < reqPreCompLen) + int pos; + if (preCompNeg == null) { - preCompNeg = ResizeTable(preCompNeg, reqPreCompLen); + pos = 0; + preCompNeg = new ECPoint[reqPreCompLen]; + } + else + { + pos = preCompNeg.Length; + if (pos < reqPreCompLen) + { + preCompNeg = WNafUtilities.ResizeTable(preCompNeg, reqPreCompLen); + } } - } - while (pos < reqPreCompLen) - { - preCompNeg[pos] = preComp[pos].Negate(); - ++pos; + while (pos < reqPreCompLen) + { + preCompNeg[pos] = preComp[pos].Negate(); + ++pos; + } } - wnafPreCompInfo.PreCompNeg = preCompNeg; + WNafPreCompInfo result = new WNafPreCompInfo(); + result.PreComp = preComp; + result.PreCompNeg = preCompNeg; + result.Twice = twiceP; + return result; } - c.SetPreCompInfo(p, PRECOMP_NAME, wnafPreCompInfo); - - return wnafPreCompInfo; - } - - private static byte[] Trim(byte[] a, int length) - { - byte[] result = new byte[length]; - Array.Copy(a, 0, result, 0, result.Length); - return result; - } - - private static int[] Trim(int[] a, int length) - { - int[] result = new int[length]; - Array.Copy(a, 0, result, 0, result.Length); - return result; - } + private bool CheckExisting(WNafPreCompInfo existingWNaf, int reqPreCompLen, bool includeNegated) + { + return existingWNaf != null + && CheckTable(existingWNaf.PreComp, reqPreCompLen) + && (!includeNegated || CheckTable(existingWNaf.PreCompNeg, reqPreCompLen)); + } - private static ECPoint[] ResizeTable(ECPoint[] a, int length) - { - ECPoint[] result = new ECPoint[length]; - Array.Copy(a, 0, result, 0, a.Length); - return result; + private bool CheckTable(ECPoint[] table, int reqLen) + { + return table != null && table.Length >= reqLen; + } } } } |