diff options
Diffstat (limited to 'crypto/src/math/ec/custom/djb/Curve25519.cs')
| -rw-r--r-- | crypto/src/math/ec/custom/djb/Curve25519.cs | 43 |
1 files changed, 32 insertions, 11 deletions
diff --git a/crypto/src/math/ec/custom/djb/Curve25519.cs b/crypto/src/math/ec/custom/djb/Curve25519.cs index c0f911a9c..f64eed244 100644 --- a/crypto/src/math/ec/custom/djb/Curve25519.cs +++ b/crypto/src/math/ec/custom/djb/Curve25519.cs @@ -10,9 +10,13 @@ namespace Org.BouncyCastle.Math.EC.Custom.Djb { public static readonly BigInteger q = Nat256.ToBigInteger(Curve25519Field.P); - private const int Curve25519_DEFAULT_COORDS = COORD_JACOBIAN_MODIFIED; - private const int CURVE25519_FE_INTS = 8; + private static readonly BigInteger C_a = new BigInteger(1, Hex.Decode("2AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA984914A144")); + private static readonly BigInteger C_b = new BigInteger(1, Hex.Decode("7B425ED097B425ED097B425ED097B425ED097B425ED097B4260B5E9C7710C864")); + private const int CURVE25519_DEFAULT_COORDS = COORD_JACOBIAN_MODIFIED; + private const int CURVE25519_FE_INTS = 8; + private static readonly ECFieldElement[] CURVE25519_AFFINE_ZS = new ECFieldElement[] { + new Curve25519FieldElement(BigInteger.One), new Curve25519FieldElement(C_a) }; protected readonly Curve25519Point m_infinity; public Curve25519() @@ -20,13 +24,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Djb { this.m_infinity = new Curve25519Point(this, null, null); - this.m_a = FromBigInteger(new BigInteger(1, - Hex.Decode("2AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA984914A144"))); - this.m_b = FromBigInteger(new BigInteger(1, - Hex.Decode("7B425ED097B425ED097B425ED097B425ED097B425ED097B4260B5E9C7710C864"))); + this.m_a = FromBigInteger(C_a); + this.m_b = FromBigInteger(C_b); this.m_order = new BigInteger(1, Hex.Decode("1000000000000000000000000000000014DEF9DEA2F79CD65812631A5CF5D3ED")); this.m_cofactor = BigInteger.ValueOf(8); - this.m_coord = Curve25519_DEFAULT_COORDS; + this.m_coord = CURVE25519_DEFAULT_COORDS; } protected override ECCurve CloneCurve() @@ -92,7 +94,7 @@ namespace Org.BouncyCastle.Math.EC.Custom.Djb } private class Curve25519LookupTable - : ECLookupTable + : AbstractECLookupTable { private readonly Curve25519 m_outer; private readonly uint[] m_table; @@ -105,12 +107,12 @@ namespace Org.BouncyCastle.Math.EC.Custom.Djb this.m_size = size; } - public virtual int Size + public override int Size { get { return m_size; } } - public virtual ECPoint Lookup(int index) + public override ECPoint Lookup(int index) { uint[] x = Nat256.Create(), y = Nat256.Create(); int pos = 0; @@ -128,7 +130,26 @@ namespace Org.BouncyCastle.Math.EC.Custom.Djb pos += (CURVE25519_FE_INTS * 2); } - return m_outer.CreateRawPoint(new Curve25519FieldElement(x), new Curve25519FieldElement(y), false); + return CreatePoint(x, y); + } + + public override ECPoint LookupVar(int index) + { + uint[] x = Nat256.Create(), y = Nat256.Create(); + int pos = index * CURVE25519_FE_INTS * 2; + + for (int j = 0; j < CURVE25519_FE_INTS; ++j) + { + x[j] = m_table[pos + j]; + y[j] = m_table[pos + CURVE25519_FE_INTS + j]; + } + + return CreatePoint(x, y); + } + + private ECPoint CreatePoint(uint[] x, uint[] y) + { + return m_outer.CreateRawPoint(new Curve25519FieldElement(x), new Curve25519FieldElement(y), CURVE25519_AFFINE_ZS, false); } } } |