diff options
Diffstat (limited to 'crypto/src/math/ec/multiplier/WNafUtilities.cs')
| -rw-r--r-- | crypto/src/math/ec/multiplier/WNafUtilities.cs | 91 |
1 files changed, 88 insertions, 3 deletions
diff --git a/crypto/src/math/ec/multiplier/WNafUtilities.cs b/crypto/src/math/ec/multiplier/WNafUtilities.cs index 01599d777..65d876449 100644 --- a/crypto/src/math/ec/multiplier/WNafUtilities.cs +++ b/crypto/src/math/ec/multiplier/WNafUtilities.cs @@ -361,6 +361,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier return System.Math.Max(2, System.Math.Min(maxWidth, w + 2)); } + [Obsolete] public static ECPoint MapPointWithPrecomp(ECPoint p, int minWidth, bool includeNegated, ECPointMap pointMap) { @@ -374,7 +375,15 @@ namespace Org.BouncyCastle.Math.EC.Multiplier public static WNafPreCompInfo Precompute(ECPoint p, int minWidth, bool includeNegated) { - return (WNafPreCompInfo)p.Curve.Precompute(p, PRECOMP_NAME, new WNafCallback(p, minWidth, includeNegated)); + return (WNafPreCompInfo)p.Curve.Precompute(p, PRECOMP_NAME, + new PrecomputeCallback(p, minWidth, includeNegated)); + } + + public static WNafPreCompInfo PrecomputeWithPointMap(ECPoint p, ECPointMap pointMap, WNafPreCompInfo fromWNaf, + bool includeNegated) + { + return (WNafPreCompInfo)p.Curve.Precompute(p, PRECOMP_NAME, + new PrecomputeWithPointMapCallback(p, pointMap, fromWNaf, includeNegated)); } private static byte[] Trim(byte[] a, int length) @@ -485,14 +494,14 @@ namespace Org.BouncyCastle.Math.EC.Multiplier } } - private class WNafCallback + private class PrecomputeCallback : IPreCompCallback { private readonly ECPoint m_p; private readonly int m_minWidth; private readonly bool m_includeNegated; - internal WNafCallback(ECPoint p, int minWidth, bool includeNegated) + internal PrecomputeCallback(ECPoint p, int minWidth, bool includeNegated) { this.m_p = p; this.m_minWidth = minWidth; @@ -665,5 +674,81 @@ namespace Org.BouncyCastle.Math.EC.Multiplier return null != table && table.Length >= reqLen; } } + + private class PrecomputeWithPointMapCallback + : IPreCompCallback + { + private readonly ECPoint m_point; + private readonly ECPointMap m_pointMap; + private readonly WNafPreCompInfo m_fromWNaf; + private readonly bool m_includeNegated; + + internal PrecomputeWithPointMapCallback(ECPoint point, ECPointMap pointMap, WNafPreCompInfo fromWNaf, + bool includeNegated) + { + this.m_point = point; + this.m_pointMap = pointMap; + this.m_fromWNaf = fromWNaf; + this.m_includeNegated = includeNegated; + } + + public PreCompInfo Precompute(PreCompInfo existing) + { + WNafPreCompInfo existingWNaf = existing as WNafPreCompInfo; + + int width = m_fromWNaf.Width; + int reqPreCompLen = m_fromWNaf.PreComp.Length; + + if (CheckExisting(existingWNaf, width, reqPreCompLen, m_includeNegated)) + return existingWNaf; + + /* + * TODO Ideally this method would support incremental calculation, but given the + * existing use-cases it would be of little-to-no benefit. + */ + WNafPreCompInfo result = new WNafPreCompInfo(); + + ECPoint twiceFrom = m_fromWNaf.Twice; + if (null != twiceFrom) + { + ECPoint twice = m_pointMap.Map(twiceFrom); + result.Twice = twice; + } + + ECPoint[] preCompFrom = m_fromWNaf.PreComp; + ECPoint[] preComp = new ECPoint[preCompFrom.Length]; + for (int i = 0; i < preCompFrom.Length; ++i) + { + preComp[i] = m_pointMap.Map(preCompFrom[i]); + } + result.PreComp = preComp; + result.Width = width; + + if (m_includeNegated) + { + ECPoint[] preCompNeg = new ECPoint[preComp.Length]; + for (int i = 0; i < preCompNeg.Length; ++i) + { + preCompNeg[i] = preComp[i].Negate(); + } + result.PreCompNeg = preCompNeg; + } + + return result; + } + + private bool CheckExisting(WNafPreCompInfo existingWNaf, int width, int reqPreCompLen, bool includeNegated) + { + return null != existingWNaf + && existingWNaf.Width >= width + && CheckTable(existingWNaf.PreComp, reqPreCompLen) + && (!includeNegated || CheckTable(existingWNaf.PreCompNeg, reqPreCompLen)); + } + + private bool CheckTable(ECPoint[] table, int reqLen) + { + return null != table && table.Length >= reqLen; + } + } } } |