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| author | Peter Dettman <peter.dettman@bouncycastle.org> | 2017-09-17 11:53:45 +0700 |
|---|---|---|
| committer | Peter Dettman <peter.dettman@bouncycastle.org> | 2017-09-17 11:53:45 +0700 |
| commit | 992f73598ec5b8325286616515536a5f6f40fa51 (patch) | |
| tree | e423d7ae6222a2d48db0b5fc0e67dd1f497436ef /crypto/src/math | |
| parent | Added GmSSL test vectors for SM3 (diff) | |
| download | BouncyCastle.NET-ed25519-992f73598ec5b8325286616515536a5f6f40fa51.tar.xz | |
Avoid infinity appearing in lookup table for FixedPointCombMultiplier
Diffstat (limited to 'crypto/src/math')
3 files changed, 17 insertions, 5 deletions
diff --git a/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs b/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs index a8ef5a77a..05bb4000b 100644 --- a/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs +++ b/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs @@ -48,7 +48,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier R = R.TwicePlus(lookupTable[index]); } - return R; + return R.Add(info.Offset); } protected virtual int GetWidthForCombSize(int combSize) diff --git a/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs b/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs index 56a6326a1..11bdadc6f 100644 --- a/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs +++ b/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs @@ -6,11 +6,13 @@ public class FixedPointPreCompInfo : PreCompInfo { + protected ECPoint m_offset = null; + /** * Array holding the precomputed <code>ECPoint</code>s used for a fixed * point multiplication. */ - protected ECPoint[] m_preComp = null; + protected ECPoint[] m_preComp = null; /** * The width used for the precomputation. If a larger width precomputation @@ -19,6 +21,12 @@ */ protected int m_width = -1; + public virtual ECPoint Offset + { + get { return m_offset; } + set { this.m_offset = value; } + } + public virtual ECPoint[] PreComp { get { return m_preComp; } diff --git a/crypto/src/math/ec/multiplier/FixedPointUtilities.cs b/crypto/src/math/ec/multiplier/FixedPointUtilities.cs index d927d010b..8e129a8f3 100644 --- a/crypto/src/math/ec/multiplier/FixedPointUtilities.cs +++ b/crypto/src/math/ec/multiplier/FixedPointUtilities.cs @@ -35,17 +35,20 @@ namespace Org.BouncyCastle.Math.EC.Multiplier int bits = GetCombSize(c); int d = (bits + minWidth - 1) / minWidth; - ECPoint[] pow2Table = new ECPoint[minWidth]; + ECPoint[] pow2Table = new ECPoint[minWidth + 1]; pow2Table[0] = 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); lookupTable = new ECPoint[n]; - lookupTable[0] = c.Infinity; + lookupTable[0] = pow2Table[0]; for (int bit = minWidth - 1; bit >= 0; --bit) { @@ -60,6 +63,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier c.NormalizeAll(lookupTable); + info.Offset = pow2Table[minWidth]; info.PreComp = lookupTable; info.Width = minWidth; |