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author | Peter Dettman <peter.dettman@bouncycastle.org> | 2018-04-15 21:12:11 +0700 |
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committer | Peter Dettman <peter.dettman@bouncycastle.org> | 2018-04-15 21:12:11 +0700 |
commit | d79a501212d4012139c714e361577669c75171aa (patch) | |
tree | f78e8c7d34c9448698e17bc341fd8d293814dd3e /crypto/src/math/ec/custom/sec/SecP160K1Curve.cs | |
parent | Update Readme.html for SHA-3 perf. opts. (diff) | |
download | BouncyCastle.NET-ed25519-d79a501212d4012139c714e361577669c75171aa.tar.xz |
Cache-safety for EC lookup tables
- creation of cache-safe lookup tables delegated to ECCurve - FixedPointCombMultiplier uses cache-safe lookup table - FixedPointCombMultiplier avoids BigInteger.TestBit
Diffstat (limited to 'crypto/src/math/ec/custom/sec/SecP160K1Curve.cs')
-rw-r--r-- | crypto/src/math/ec/custom/sec/SecP160K1Curve.cs | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/crypto/src/math/ec/custom/sec/SecP160K1Curve.cs b/crypto/src/math/ec/custom/sec/SecP160K1Curve.cs index 7d45c6227..234c86b87 100644 --- a/crypto/src/math/ec/custom/sec/SecP160K1Curve.cs +++ b/crypto/src/math/ec/custom/sec/SecP160K1Curve.cs @@ -1,5 +1,6 @@ using System; +using Org.BouncyCastle.Math.Raw; using Org.BouncyCastle.Utilities.Encoders; namespace Org.BouncyCastle.Math.EC.Custom.Sec @@ -10,6 +11,7 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec public static readonly BigInteger q = SecP160R2Curve.q; private const int SECP160K1_DEFAULT_COORDS = COORD_JACOBIAN; + private const int SECP160K1_FE_INTS = 5; protected readonly SecP160K1Point m_infinity; @@ -70,5 +72,62 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec { return new SecP160K1Point(this, x, y, zs, withCompression); } + + public override ECLookupTable CreateCacheSafeLookupTable(ECPoint[] points, int off, int len) + { + uint[] table = new uint[len * SECP160K1_FE_INTS * 2]; + { + int pos = 0; + for (int i = 0; i < len; ++i) + { + ECPoint p = points[off + i]; + Nat160.Copy(((SecP160R2FieldElement)p.RawXCoord).x, 0, table, pos); pos += SECP160K1_FE_INTS; + Nat160.Copy(((SecP160R2FieldElement)p.RawYCoord).x, 0, table, pos); pos += SECP160K1_FE_INTS; + } + } + + return new SecP160K1LookupTable(this, table, len); + } + + private class SecP160K1LookupTable + : ECLookupTable + { + private readonly SecP160K1Curve m_outer; + private readonly uint[] m_table; + private readonly int m_size; + + internal SecP160K1LookupTable(SecP160K1Curve outer, uint[] 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) + { + uint[] x = Nat256.Create(), y = Nat256.Create(); + int pos = 0; + + for (int i = 0; i < m_size; ++i) + { + uint MASK = (uint)(((i ^ index) - 1) >> 31); + + for (int j = 0; j < SECP160K1_FE_INTS; ++j) + { + x[j] ^= m_table[pos + j] & MASK; + y[j] ^= m_table[pos + SECP160K1_FE_INTS + j] & MASK; + } + + pos += (SECP160K1_FE_INTS * 2); + } + + return m_outer.CreateRawPoint(new SecP160R2FieldElement(x), new SecP160R2FieldElement(y), false); + } + } } } |