diff options
Diffstat (limited to 'crypto/src/math/ec/ECCurve.cs')
| -rw-r--r-- | crypto/src/math/ec/ECCurve.cs | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/crypto/src/math/ec/ECCurve.cs b/crypto/src/math/ec/ECCurve.cs index 6ccd97e7b..6a9342722 100644 --- a/crypto/src/math/ec/ECCurve.cs +++ b/crypto/src/math/ec/ECCurve.cs @@ -5,6 +5,7 @@ using Org.BouncyCastle.Math.EC.Abc; using Org.BouncyCastle.Math.EC.Endo; using Org.BouncyCastle.Math.EC.Multiplier; using Org.BouncyCastle.Math.Field; +using Org.BouncyCastle.Math.Raw; using Org.BouncyCastle.Utilities; namespace Org.BouncyCastle.Math.EC @@ -321,6 +322,33 @@ namespace Org.BouncyCastle.Math.EC get { return m_coord; } } + /** + * Create a cache-safe lookup table for the specified sequence of points. All the points MUST + * belong to this <code>ECCurve</code> instance, and MUST already be normalized. + */ + public virtual ECLookupTable CreateCacheSafeLookupTable(ECPoint[] points, int off, int len) + { + int FE_BYTES = (FieldSize + 7) / 8; + byte[] table = new byte[len * FE_BYTES * 2]; + { + int pos = 0; + for (int i = 0; i < len; ++i) + { + ECPoint p = points[off + i]; + byte[] px = p.RawXCoord.ToBigInteger().ToByteArray(); + byte[] py = p.RawYCoord.ToBigInteger().ToByteArray(); + + int pxStart = px.Length > FE_BYTES ? 1 : 0, pxLen = px.Length - pxStart; + int pyStart = py.Length > FE_BYTES ? 1 : 0, pyLen = py.Length - pyStart; + + Array.Copy(px, pxStart, table, pos + FE_BYTES - pxLen, pxLen); pos += FE_BYTES; + Array.Copy(py, pyStart, table, pos + FE_BYTES - pyLen, pyLen); pos += FE_BYTES; + } + } + + return new DefaultLookupTable(this, table, len); + } + protected virtual void CheckPoint(ECPoint point) { if (null == point || (this != point.Curve)) @@ -468,6 +496,50 @@ namespace Org.BouncyCastle.Math.EC return p; } + + private class DefaultLookupTable + : ECLookupTable + { + private readonly ECCurve m_outer; + private readonly byte[] m_table; + private readonly int m_size; + + internal DefaultLookupTable(ECCurve outer, byte[] table, int size) + { + this.m_outer = outer; + this.m_table = table; + this.m_size = size; + } + + public virtual int Size + { + get { return m_size; } + } + + public virtual ECPoint Lookup(int index) + { + int FE_BYTES = (m_outer.FieldSize + 7) / 8; + byte[] x = new byte[FE_BYTES], y = new byte[FE_BYTES]; + int pos = 0; + + for (int i = 0; i < m_size; ++i) + { + byte MASK = (byte)(((i ^ index) - 1) >> 31); + + for (int j = 0; j < FE_BYTES; ++j) + { + x[j] ^= (byte)(m_table[pos + j] & MASK); + y[j] ^= (byte)(m_table[pos + FE_BYTES + j] & MASK); + } + + pos += (FE_BYTES * 2); + } + + ECFieldElement X = m_outer.FromBigInteger(new BigInteger(1, x)); + ECFieldElement Y = m_outer.FromBigInteger(new BigInteger(1, y)); + return m_outer.CreateRawPoint(X, Y, false); + } + } } public abstract class AbstractFpCurve @@ -1127,5 +1199,70 @@ namespace Org.BouncyCastle.Math.EC { get { return m_cofactor; } } + + public override ECLookupTable CreateCacheSafeLookupTable(ECPoint[] points, int off, int len) + { + int FE_LONGS = (m + 63) / 64; + + long[] table = new long[len * FE_LONGS * 2]; + { + int pos = 0; + for (int i = 0; i < len; ++i) + { + ECPoint p = points[off + i]; + ((F2mFieldElement)p.RawXCoord).x.CopyTo(table, pos); pos += FE_LONGS; + ((F2mFieldElement)p.RawYCoord).x.CopyTo(table, pos); pos += FE_LONGS; + } + } + + return new DefaultF2mLookupTable(this, table, len); + } + + private class DefaultF2mLookupTable + : ECLookupTable + { + private readonly F2mCurve m_outer; + private readonly long[] m_table; + private readonly int m_size; + + internal DefaultF2mLookupTable(F2mCurve outer, long[] table, int size) + { + this.m_outer = outer; + this.m_table = table; + this.m_size = size; + } + + public virtual int Size + { + get { return m_size; } + } + + public virtual ECPoint Lookup(int index) + { + int m = m_outer.m; + int[] ks = m_outer.IsTrinomial() ? new int[]{ m_outer.k1 } : new int[]{ m_outer.k1, m_outer.k2, m_outer.k3 }; + + int FE_LONGS = (m_outer.m + 63) / 64; + long[] x = new long[FE_LONGS], y = new long[FE_LONGS]; + int pos = 0; + + for (int i = 0; i < m_size; ++i) + { + long MASK =((i ^ index) - 1) >> 31; + + for (int j = 0; j < FE_LONGS; ++j) + { + x[j] ^= m_table[pos + j] & MASK; + y[j] ^= m_table[pos + FE_LONGS + j] & MASK; + } + + pos += (FE_LONGS * 2); + } + + ECFieldElement X = new F2mFieldElement(m, ks, new LongArray(x)); + ECFieldElement Y = new F2mFieldElement(m, ks, new LongArray(y)); + return m_outer.CreateRawPoint(X, Y, false); + } + } } } |