Remove bridging version of Curve25519

6 files changed, 50 insertions, 1068 deletions

diff --git a/crypto/src/crypto/ec/CustomNamedCurves.cs b/crypto/src/crypto/ec/CustomNamedCurves.cs
index 166c0ad75..bf2b7f486 100644
--- a/crypto/src/crypto/ec/CustomNamedCurves.cs
+++ b/crypto/src/crypto/ec/CustomNamedCurves.cs
@@ -7,7 +7,6 @@ using Org.BouncyCastle.Asn1.Sec;
 using Org.BouncyCastle.Asn1.X9;
 using Org.BouncyCastle.Math;
 using Org.BouncyCastle.Math.EC;
-using Org.BouncyCastle.Math.EC.Custom.Djb;
 using Org.BouncyCastle.Math.EC.Custom.GM;
 using Org.BouncyCastle.Math.EC.Custom.Sec;
 using Org.BouncyCastle.Math.EC.Endo;
@@ -42,42 +41,6 @@ namespace Org.BouncyCastle.Crypto.EC
         }
 
         /*
-         * curve25519
-         */
-        internal class Curve25519Holder
-            : X9ECParametersHolder
-        {
-            private Curve25519Holder() {}
-
-            internal static readonly X9ECParametersHolder Instance = new Curve25519Holder();
-
-            protected override ECCurve CreateCurve()
-            {
-                return ConfigureCurve(new Curve25519());
-            }
-
-            protected override X9ECParameters CreateParameters()
-            {
-                byte[] S = null;
-                ECCurve curve = Curve;
-
-                /*
-                 * NOTE: Curve25519 was specified in Montgomery form. Rewriting in Weierstrass form
-                 * involves substitution of variables, so the base-point x coordinate is 9 + (486662 / 3).
-                 * 
-                 * The Curve25519 paper doesn't say which of the two possible y values the base
-                 * point has. The choice here is guided by language in the Ed25519 paper.
-                 * 
-                 * (The other possible y value is 5F51E65E475F794B1FE122D388B72EB36DC2B28192839E4DD6163A5D81312C14) 
-                 */
-                X9ECPoint G = ConfigureBasepoint(curve,
-                    "042AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD245A20AE19A1B8A086B4E01EDD2C7748D14C923D4D7E6D7C61B229E9C5A27ECED3D9");
-
-                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
-            }
-        }
-
-        /*
          * secp128r1
          */
         internal class SecP128R1Holder
@@ -919,14 +882,7 @@ namespace Org.BouncyCastle.Crypto.EC
         private static readonly IDictionary oidToName = Platform.CreateHashtable();
         private static readonly IList names = Platform.CreateArrayList();
 
-        private static void DefineCurve(string name, X9ECParametersHolder holder)
-        {
-            names.Add(name);
-            name = Platform.ToUpperInvariant(name);
-            nameToCurve.Add(name, holder);
-        }
-
-        private static void DefineCurveWithOid(string name, DerObjectIdentifier oid, X9ECParametersHolder holder)
+        private static void DefineCurve(string name, DerObjectIdentifier oid, X9ECParametersHolder holder)
         {
             names.Add(name);
             oidToName.Add(oid, name);
@@ -949,44 +905,42 @@ namespace Org.BouncyCastle.Crypto.EC
 
         static CustomNamedCurves()
         {
-            DefineCurve("curve25519", Curve25519Holder.Instance);
-
-            //DefineCurveWithOid("secp112r1", SecObjectIdentifiers.SecP112r1, SecP112R1Holder.Instance);
-            //DefineCurveWithOid("secp112r2", SecObjectIdentifiers.SecP112r2, SecP112R2Holder.Instance);
-            DefineCurveWithOid("secp128r1", SecObjectIdentifiers.SecP128r1, SecP128R1Holder.Instance);
-            //DefineCurveWithOid("secp128r2", SecObjectIdentifiers.SecP128r2, SecP128R2Holder.Instance);
-            DefineCurveWithOid("secp160k1", SecObjectIdentifiers.SecP160k1, SecP160K1Holder.Instance);
-            DefineCurveWithOid("secp160r1", SecObjectIdentifiers.SecP160r1, SecP160R1Holder.Instance);
-            DefineCurveWithOid("secp160r2", SecObjectIdentifiers.SecP160r2, SecP160R2Holder.Instance);
-            DefineCurveWithOid("secp192k1", SecObjectIdentifiers.SecP192k1, SecP192K1Holder.Instance);
-            DefineCurveWithOid("secp192r1", SecObjectIdentifiers.SecP192r1, SecP192R1Holder.Instance);
-            DefineCurveWithOid("secp224k1", SecObjectIdentifiers.SecP224k1, SecP224K1Holder.Instance);
-            DefineCurveWithOid("secp224r1", SecObjectIdentifiers.SecP224r1, SecP224R1Holder.Instance);
-            DefineCurveWithOid("secp256k1", SecObjectIdentifiers.SecP256k1, SecP256K1Holder.Instance);
-            DefineCurveWithOid("secp256r1", SecObjectIdentifiers.SecP256r1, SecP256R1Holder.Instance);
-            DefineCurveWithOid("secp384r1", SecObjectIdentifiers.SecP384r1, SecP384R1Holder.Instance);
-            DefineCurveWithOid("secp521r1", SecObjectIdentifiers.SecP521r1, SecP521R1Holder.Instance);
-
-            DefineCurveWithOid("sect113r1", SecObjectIdentifiers.SecT113r1, SecT113R1Holder.Instance);
-            DefineCurveWithOid("sect113r2", SecObjectIdentifiers.SecT113r2, SecT113R2Holder.Instance);
-            DefineCurveWithOid("sect131r1", SecObjectIdentifiers.SecT131r1, SecT131R1Holder.Instance);
-            DefineCurveWithOid("sect131r2", SecObjectIdentifiers.SecT131r2, SecT131R2Holder.Instance);
-            DefineCurveWithOid("sect163k1", SecObjectIdentifiers.SecT163k1, SecT163K1Holder.Instance);
-            DefineCurveWithOid("sect163r1", SecObjectIdentifiers.SecT163r1, SecT163R1Holder.Instance);
-            DefineCurveWithOid("sect163r2", SecObjectIdentifiers.SecT163r2, SecT163R2Holder.Instance);
-            DefineCurveWithOid("sect193r1", SecObjectIdentifiers.SecT193r1, SecT193R1Holder.Instance);
-            DefineCurveWithOid("sect193r2", SecObjectIdentifiers.SecT193r2, SecT193R2Holder.Instance);
-            DefineCurveWithOid("sect233k1", SecObjectIdentifiers.SecT233k1, SecT233K1Holder.Instance);
-            DefineCurveWithOid("sect233r1", SecObjectIdentifiers.SecT233r1, SecT233R1Holder.Instance);
-            DefineCurveWithOid("sect239k1", SecObjectIdentifiers.SecT239k1, SecT239K1Holder.Instance);
-            DefineCurveWithOid("sect283k1", SecObjectIdentifiers.SecT283k1, SecT283K1Holder.Instance);
-            DefineCurveWithOid("sect283r1", SecObjectIdentifiers.SecT283r1, SecT283R1Holder.Instance);
-            DefineCurveWithOid("sect409k1", SecObjectIdentifiers.SecT409k1, SecT409K1Holder.Instance);
-            DefineCurveWithOid("sect409r1", SecObjectIdentifiers.SecT409r1, SecT409R1Holder.Instance);
-            DefineCurveWithOid("sect571k1", SecObjectIdentifiers.SecT571k1, SecT571K1Holder.Instance);
-            DefineCurveWithOid("sect571r1", SecObjectIdentifiers.SecT571r1, SecT571R1Holder.Instance);
-
-            DefineCurveWithOid("sm2p256v1", GMObjectIdentifiers.sm2p256v1, SM2P256V1Holder.Instance);
+            //DefineCurve("secp112r1", SecObjectIdentifiers.SecP112r1, SecP112R1Holder.Instance);
+            //DefineCurve("secp112r2", SecObjectIdentifiers.SecP112r2, SecP112R2Holder.Instance);
+            DefineCurve("secp128r1", SecObjectIdentifiers.SecP128r1, SecP128R1Holder.Instance);
+            //DefineCurve("secp128r2", SecObjectIdentifiers.SecP128r2, SecP128R2Holder.Instance);
+            DefineCurve("secp160k1", SecObjectIdentifiers.SecP160k1, SecP160K1Holder.Instance);
+            DefineCurve("secp160r1", SecObjectIdentifiers.SecP160r1, SecP160R1Holder.Instance);
+            DefineCurve("secp160r2", SecObjectIdentifiers.SecP160r2, SecP160R2Holder.Instance);
+            DefineCurve("secp192k1", SecObjectIdentifiers.SecP192k1, SecP192K1Holder.Instance);
+            DefineCurve("secp192r1", SecObjectIdentifiers.SecP192r1, SecP192R1Holder.Instance);
+            DefineCurve("secp224k1", SecObjectIdentifiers.SecP224k1, SecP224K1Holder.Instance);
+            DefineCurve("secp224r1", SecObjectIdentifiers.SecP224r1, SecP224R1Holder.Instance);
+            DefineCurve("secp256k1", SecObjectIdentifiers.SecP256k1, SecP256K1Holder.Instance);
+            DefineCurve("secp256r1", SecObjectIdentifiers.SecP256r1, SecP256R1Holder.Instance);
+            DefineCurve("secp384r1", SecObjectIdentifiers.SecP384r1, SecP384R1Holder.Instance);
+            DefineCurve("secp521r1", SecObjectIdentifiers.SecP521r1, SecP521R1Holder.Instance);
+
+            DefineCurve("sect113r1", SecObjectIdentifiers.SecT113r1, SecT113R1Holder.Instance);
+            DefineCurve("sect113r2", SecObjectIdentifiers.SecT113r2, SecT113R2Holder.Instance);
+            DefineCurve("sect131r1", SecObjectIdentifiers.SecT131r1, SecT131R1Holder.Instance);
+            DefineCurve("sect131r2", SecObjectIdentifiers.SecT131r2, SecT131R2Holder.Instance);
+            DefineCurve("sect163k1", SecObjectIdentifiers.SecT163k1, SecT163K1Holder.Instance);
+            DefineCurve("sect163r1", SecObjectIdentifiers.SecT163r1, SecT163R1Holder.Instance);
+            DefineCurve("sect163r2", SecObjectIdentifiers.SecT163r2, SecT163R2Holder.Instance);
+            DefineCurve("sect193r1", SecObjectIdentifiers.SecT193r1, SecT193R1Holder.Instance);
+            DefineCurve("sect193r2", SecObjectIdentifiers.SecT193r2, SecT193R2Holder.Instance);
+            DefineCurve("sect233k1", SecObjectIdentifiers.SecT233k1, SecT233K1Holder.Instance);
+            DefineCurve("sect233r1", SecObjectIdentifiers.SecT233r1, SecT233R1Holder.Instance);
+            DefineCurve("sect239k1", SecObjectIdentifiers.SecT239k1, SecT239K1Holder.Instance);
+            DefineCurve("sect283k1", SecObjectIdentifiers.SecT283k1, SecT283K1Holder.Instance);
+            DefineCurve("sect283r1", SecObjectIdentifiers.SecT283r1, SecT283R1Holder.Instance);
+            DefineCurve("sect409k1", SecObjectIdentifiers.SecT409k1, SecT409K1Holder.Instance);
+            DefineCurve("sect409r1", SecObjectIdentifiers.SecT409r1, SecT409R1Holder.Instance);
+            DefineCurve("sect571k1", SecObjectIdentifiers.SecT571k1, SecT571K1Holder.Instance);
+            DefineCurve("sect571r1", SecObjectIdentifiers.SecT571r1, SecT571R1Holder.Instance);
+
+            DefineCurve("sm2p256v1", GMObjectIdentifiers.sm2p256v1, SM2P256V1Holder.Instance);
 
             DefineCurveAlias("B-163", SecObjectIdentifiers.SecT163r2);
             DefineCurveAlias("B-233", SecObjectIdentifiers.SecT233r1);
diff --git a/crypto/src/math/ec/custom/djb/Curve25519.cs b/crypto/src/math/ec/custom/djb/Curve25519.cs
deleted file mode 100644
index 380be7252..000000000
--- a/crypto/src/math/ec/custom/djb/Curve25519.cs
+++ /dev/null
@@ -1,171 +0,0 @@
-using System;
-
-using Org.BouncyCastle.Math.Raw;
-using Org.BouncyCastle.Security;
-using Org.BouncyCastle.Utilities.Encoders;
-
-namespace Org.BouncyCastle.Math.EC.Custom.Djb
-{
-    internal class Curve25519
-        : AbstractFpCurve
-    {
-        public static readonly BigInteger q = Curve25519FieldElement.Q;
-
-        private static readonly BigInteger C_a = new BigInteger(1, Hex.DecodeStrict("2AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA984914A144"));
-        private static readonly BigInteger C_b = new BigInteger(1, Hex.DecodeStrict("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()
-            : base(q)
-        {
-            this.m_infinity = new Curve25519Point(this, null, null);
-
-            this.m_a = FromBigInteger(C_a);
-            this.m_b = FromBigInteger(C_b);
-            this.m_order = new BigInteger(1, Hex.DecodeStrict("1000000000000000000000000000000014DEF9DEA2F79CD65812631A5CF5D3ED"));
-            this.m_cofactor = BigInteger.ValueOf(8);
-            this.m_coord = CURVE25519_DEFAULT_COORDS;
-        }
-
-        protected override ECCurve CloneCurve()
-        {
-            return new Curve25519();
-        }
-
-        public override bool SupportsCoordinateSystem(int coord)
-        {
-            switch (coord)
-            {
-            case COORD_JACOBIAN_MODIFIED:
-                return true;
-            default:
-                return false;
-            }
-        }
-
-        public virtual BigInteger Q
-        {
-            get { return q; }
-        }
-
-        public override ECPoint Infinity
-        {
-            get { return m_infinity; }
-        }
-
-        public override int FieldSize
-        {
-            get { return q.BitLength; }
-        }
-
-        public override ECFieldElement FromBigInteger(BigInteger x)
-        {
-            return new Curve25519FieldElement(x);
-        }
-
-        protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y)
-        {
-            return new Curve25519Point(this, x, y);
-        }
-
-        protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
-        {
-            return new Curve25519Point(this, x, y, zs);
-        }
-
-        public override ECLookupTable CreateCacheSafeLookupTable(ECPoint[] points, int off, int len)
-        {
-            uint[] table = new uint[len * CURVE25519_FE_INTS * 2];
-            {
-                int pos = 0;
-                for (int i = 0; i < len; ++i)
-                {
-                    ECPoint p = points[off + i];
-                    Nat256.Copy(((Curve25519FieldElement)p.RawXCoord).x, 0, table, pos); pos += CURVE25519_FE_INTS;
-                    Nat256.Copy(((Curve25519FieldElement)p.RawYCoord).x, 0, table, pos); pos += CURVE25519_FE_INTS;
-                }
-            }
-
-            return new Curve25519LookupTable(this, table, len);
-        }
-
-        public override ECFieldElement RandomFieldElement(SecureRandom r)
-        {
-            uint[] x = Nat256.Create();
-            Curve25519Field.Random(r, x);
-            return new Curve25519FieldElement(x);
-        }
-
-        public override ECFieldElement RandomFieldElementMult(SecureRandom r)
-        {
-            uint[] x = Nat256.Create();
-            Curve25519Field.RandomMult(r, x);
-            return new Curve25519FieldElement(x);
-        }
-
-        private class Curve25519LookupTable
-            : AbstractECLookupTable
-        {
-            private readonly Curve25519 m_outer;
-            private readonly uint[] m_table;
-            private readonly int m_size;
-
-            internal Curve25519LookupTable(Curve25519 outer, uint[] table, int size)
-            {
-                this.m_outer = outer;
-                this.m_table = table;
-                this.m_size = size;
-            }
-
-            public override int Size
-            {
-                get { return m_size; }
-            }
-
-            public override 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 < CURVE25519_FE_INTS; ++j)
-                    {
-                        x[j] ^= m_table[pos + j] & MASK;
-                        y[j] ^= m_table[pos + CURVE25519_FE_INTS + j] & MASK;
-                    }
-
-                    pos += (CURVE25519_FE_INTS * 2);
-                }
-
-                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);
-            }
-        }
-    }
-}
diff --git a/crypto/src/math/ec/custom/djb/Curve25519Field.cs b/crypto/src/math/ec/custom/djb/Curve25519Field.cs
deleted file mode 100644
index 31416249d..000000000
--- a/crypto/src/math/ec/custom/djb/Curve25519Field.cs
+++ /dev/null
@@ -1,292 +0,0 @@
-using System;
-using System.Diagnostics;
-
-using Org.BouncyCastle.Crypto.Utilities;
-using Org.BouncyCastle.Math.Raw;
-using Org.BouncyCastle.Security;
-
-namespace Org.BouncyCastle.Math.EC.Custom.Djb
-{
-    internal class Curve25519Field
-    {
-        // 2^255 - 19
-        internal static readonly uint[] P = new uint[]{ 0xFFFFFFED, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
-            0xFFFFFFFF, 0xFFFFFFFF, 0x7FFFFFFF };
-        private const uint P7 = 0x7FFFFFFF;
-        private static readonly uint[] PExt = new uint[]{ 0x00000169, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
-            0x00000000, 0x00000000, 0x00000000, 0xFFFFFFED, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
-            0xFFFFFFFF, 0x3FFFFFFF };
-        private const uint PInv = 0x13;
-
-        public static void Add(uint[] x, uint[] y, uint[] z)
-        {
-            Nat256.Add(x, y, z);
-            if (Nat256.Gte(z, P))
-            {
-                SubPFrom(z);
-            }
-        }
-
-        public static void AddExt(uint[] xx, uint[] yy, uint[] zz)
-        {
-            Nat.Add(16, xx, yy, zz);
-            if (Nat.Gte(16, zz, PExt))
-            {
-                SubPExtFrom(zz);
-            }
-        }
-
-        public static void AddOne(uint[] x, uint[] z)
-        {
-            Nat.Inc(8, x, z);
-            if (Nat256.Gte(z, P))
-            {
-                SubPFrom(z);
-            }
-        }
-
-        public static uint[] FromBigInteger(BigInteger x)
-        {
-            uint[] z = Nat.FromBigInteger(256, x);
-            while (Nat256.Gte(z, P))
-            {
-                Nat256.SubFrom(P, z);
-            }
-            return z;
-        }
-
-        public static void Half(uint[] x, uint[] z)
-        {
-            if ((x[0] & 1) == 0)
-            {
-                Nat.ShiftDownBit(8, x, 0, z);
-            }
-            else
-            {
-                Nat256.Add(x, P, z);
-                Nat.ShiftDownBit(8, z, 0);
-            }
-        }
-
-        public static void Inv(uint[] x, uint[] z)
-        {
-            Mod.CheckedModOddInverse(P, x, z);
-        }
-
-        public static int IsZero(uint[] x)
-        {
-            uint d = 0;
-            for (int i = 0; i < 8; ++i)
-            {
-                d |= x[i];
-            }
-            d = (d >> 1) | (d & 1);
-            return ((int)d - 1) >> 31;
-        }
-
-        public static void Multiply(uint[] x, uint[] y, uint[] z)
-        {
-            uint[] tt = Nat256.CreateExt();
-            Nat256.Mul(x, y, tt);
-            Reduce(tt, z);
-        }
-
-        public static void MultiplyAddToExt(uint[] x, uint[] y, uint[] zz)
-        {
-            Nat256.MulAddTo(x, y, zz);
-            if (Nat.Gte(16, zz, PExt))
-            {
-                SubPExtFrom(zz);
-            }
-        }
-
-        public static void Negate(uint[] x, uint[] z)
-        {
-            if (0 != IsZero(x))
-            {
-                Nat256.Sub(P, P, z);
-            }
-            else
-            {
-                Nat256.Sub(P, x, z);
-            }
-        }
-
-        public static void Random(SecureRandom r, uint[] z)
-        {
-            byte[] bb = new byte[8 * 4];
-            do
-            {
-                r.NextBytes(bb);
-                Pack.LE_To_UInt32(bb, 0, z, 0, 8);
-                z[7] &= P7;
-            }
-            while (0 == Nat.LessThan(8, z, P));
-        }
-
-        public static void RandomMult(SecureRandom r, uint[] z)
-        {
-            do
-            {
-                Random(r, z);
-            }
-            while (0 != IsZero(z));
-        }
-
-        public static void Reduce(uint[] xx, uint[] z)
-        {
-            Debug.Assert(xx[15] >> 30 == 0);
-
-            uint xx07 = xx[7];
-            Nat.ShiftUpBit(8, xx, 8, xx07, z, 0);
-            uint c = Nat256.MulByWordAddTo(PInv, xx, z) << 1;
-            uint z7 = z[7];
-            c += (z7 >> 31) - (xx07 >> 31);
-            z7 &= P7;
-            z7 += Nat.AddWordTo(7, c * PInv, z);
-            z[7] = z7;
-            if (z7 >= P7 && Nat256.Gte(z, P))
-            {
-                SubPFrom(z);
-            }
-        }
-
-        public static void Reduce27(uint x, uint[] z)
-        {
-            Debug.Assert(x >> 26 == 0);
-
-            uint z7 = z[7];
-            uint c = (x << 1 | z7 >> 31);
-            z7 &= P7;
-            z7 += Nat.AddWordTo(7, c * PInv, z);
-            z[7] = z7;
-            if (z7 >= P7 && Nat256.Gte(z, P))
-            {
-                SubPFrom(z);
-            }
-        }
-
-        public static void Square(uint[] x, uint[] z)
-        {
-            uint[] tt = Nat256.CreateExt();
-            Nat256.Square(x, tt);
-            Reduce(tt, z);
-        }
-
-        public static void SquareN(uint[] x, int n, uint[] z)
-        {
-            Debug.Assert(n > 0);
-
-            uint[] tt = Nat256.CreateExt();
-            Nat256.Square(x, tt);
-            Reduce(tt, z);
-
-            while (--n > 0)
-            {
-                Nat256.Square(z, tt);
-                Reduce(tt, z);
-            }
-        }
-
-        public static void Subtract(uint[] x, uint[] y, uint[] z)
-        {
-            int c = Nat256.Sub(x, y, z);
-            if (c != 0)
-            {
-                AddPTo(z);
-            }
-        }
-
-        public static void SubtractExt(uint[] xx, uint[] yy, uint[] zz)
-        {
-            int c = Nat.Sub(16, xx, yy, zz);
-            if (c != 0)
-            {
-                AddPExtTo(zz);
-            }
-        }
-
-        public static void Twice(uint[] x, uint[] z)
-        {
-            Nat.ShiftUpBit(8, x, 0, z);
-            if (Nat256.Gte(z, P))
-            {
-                SubPFrom(z);
-            }
-        }
-
-        private static uint AddPTo(uint[] z)
-        {
-            long c = (long)z[0] - PInv;
-            z[0] = (uint)c;
-            c >>= 32;
-            if (c != 0)
-            {
-                c = Nat.DecAt(7, z, 1);
-            }
-            c += (long)z[7] + (P7 + 1);
-            z[7] = (uint)c;
-            c >>= 32;
-            return (uint)c;
-        }
-
-        private static uint AddPExtTo(uint[] zz)
-        {
-            long c = (long)zz[0] + PExt[0];
-            zz[0] = (uint)c;
-            c >>= 32;
-            if (c != 0)
-            {
-                c = Nat.IncAt(8, zz, 1);
-            }
-            c += (long)zz[8] - PInv;
-            zz[8] = (uint)c;
-            c >>= 32;
-            if (c != 0)
-            {
-                c = Nat.DecAt(15, zz, 9);
-            }
-            c += (long)zz[15] + (PExt[15] + 1);
-            zz[15] = (uint)c;
-            c >>= 32;
-            return (uint)c;
-        }
-
-        private static int SubPFrom(uint[] z)
-        {
-            long c = (long)z[0] + PInv;
-            z[0] = (uint)c;
-            c >>= 32;
-            if (c != 0)
-            {
-                c = Nat.IncAt(7, z, 1);
-            }
-            c += (long)z[7] - (P7 + 1);
-            z[7] = (uint)c;
-            c >>= 32;
-            return (int)c;
-        }
-
-        private static int SubPExtFrom(uint[] zz)
-        {
-            long c = (long)zz[0] - PExt[0];
-            zz[0] = (uint)c;
-            c >>= 32;
-            if (c != 0)
-            {
-                c = Nat.DecAt(8, zz, 1);
-            }
-            c += (long)zz[8] + PInv;
-            zz[8] = (uint)c;
-            c >>= 32;
-            if (c != 0)
-            {
-                c = Nat.IncAt(15, zz, 9);
-            }
-            c += (long)zz[15] - (PExt[15] + 1);
-            zz[15] = (uint)c;
-            c >>= 32;
-            return (int)c;
-        }
-    }
-}
diff --git a/crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs b/crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs
deleted file mode 100644
index a5509841d..000000000
--- a/crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs
+++ /dev/null
@@ -1,233 +0,0 @@
-using System;
-
-using Org.BouncyCastle.Math.Raw;
-using Org.BouncyCastle.Utilities;
-
-namespace Org.BouncyCastle.Math.EC.Custom.Djb
-{
-    internal class Curve25519FieldElement
-        : AbstractFpFieldElement
-    {
-        public static readonly BigInteger Q = Nat256.ToBigInteger(Curve25519Field.P);
-
-        // Calculated as ECConstants.TWO.modPow(Q.shiftRight(2), Q)
-        private static readonly uint[] PRECOMP_POW2 = new uint[]{ 0x4a0ea0b0, 0xc4ee1b27, 0xad2fe478, 0x2f431806,
-            0x3dfbd7a7, 0x2b4d0099, 0x4fc1df0b, 0x2b832480 };
-
-        protected internal readonly uint[] x;
-
-        public Curve25519FieldElement(BigInteger x)
-        {
-            if (x == null || x.SignValue < 0 || x.CompareTo(Q) >= 0)
-                throw new ArgumentException("value invalid for Curve25519FieldElement", "x");
-
-            this.x = Curve25519Field.FromBigInteger(x);
-        }
-
-        public Curve25519FieldElement()
-        {
-            this.x = Nat256.Create();
-        }
-
-        protected internal Curve25519FieldElement(uint[] x)
-        {
-            this.x = x;
-        }
-
-        public override bool IsZero
-        {
-            get { return Nat256.IsZero(x); }
-        }
-
-        public override bool IsOne
-        {
-            get { return Nat256.IsOne(x); }
-        }
-
-        public override bool TestBitZero()
-        {
-            return Nat256.GetBit(x, 0) == 1;
-        }
-
-        public override BigInteger ToBigInteger()
-        {
-            return Nat256.ToBigInteger(x);
-        }
-
-        public override string FieldName
-        {
-            get { return "Curve25519Field"; }
-        }
-
-        public override int FieldSize
-        {
-            get { return Q.BitLength; }
-        }
-
-        public override ECFieldElement Add(ECFieldElement b)
-        {
-            uint[] z = Nat256.Create();
-            Curve25519Field.Add(x, ((Curve25519FieldElement)b).x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        public override ECFieldElement AddOne()
-        {
-            uint[] z = Nat256.Create();
-            Curve25519Field.AddOne(x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        public override ECFieldElement Subtract(ECFieldElement b)
-        {
-            uint[] z = Nat256.Create();
-            Curve25519Field.Subtract(x, ((Curve25519FieldElement)b).x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        public override ECFieldElement Multiply(ECFieldElement b)
-        {
-            uint[] z = Nat256.Create();
-            Curve25519Field.Multiply(x, ((Curve25519FieldElement)b).x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        public override ECFieldElement Divide(ECFieldElement b)
-        {
-            //return Multiply(b.Invert());
-            uint[] z = Nat256.Create();
-            Curve25519Field.Inv(((Curve25519FieldElement)b).x, z);
-            Curve25519Field.Multiply(z, x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        public override ECFieldElement Negate()
-        {
-            uint[] z = Nat256.Create();
-            Curve25519Field.Negate(x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        public override ECFieldElement Square()
-        {
-            uint[] z = Nat256.Create();
-            Curve25519Field.Square(x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        public override ECFieldElement Invert()
-        {
-            //return new Curve25519FieldElement(ToBigInteger().ModInverse(Q));
-            uint[] z = Nat256.Create();
-            Curve25519Field.Inv(x, z);
-            return new Curve25519FieldElement(z);
-        }
-
-        /**
-         * return a sqrt root - the routine verifies that the calculation returns the right value - if
-         * none exists it returns null.
-         */
-        public override ECFieldElement Sqrt()
-        {
-            /*
-             * Q == 8m + 5, so we use Pocklington's method for this case.
-             *
-             * First, raise this element to the exponent 2^252 - 2^1 (i.e. m + 1)
-             * 
-             * Breaking up the exponent's binary representation into "repunits", we get:
-             * { 251 1s } { 1 0s }
-             * 
-             * Therefore we need an addition chain containing 251 (the lengths of the repunits)
-             * We use: 1, 2, 3, 4, 7, 11, 15, 30, 60, 120, 131, [251]
-             */
-
-            uint[] x1 = this.x;
-            if (Nat256.IsZero(x1) || Nat256.IsOne(x1))
-                return this;
-
-            uint[] x2 = Nat256.Create();
-            Curve25519Field.Square(x1, x2);
-            Curve25519Field.Multiply(x2, x1, x2);
-            uint[] x3 = x2;
-            Curve25519Field.Square(x2, x3);
-            Curve25519Field.Multiply(x3, x1, x3);
-            uint[] x4 = Nat256.Create();
-            Curve25519Field.Square(x3, x4);
-            Curve25519Field.Multiply(x4, x1, x4);
-            uint[] x7 = Nat256.Create();
-            Curve25519Field.SquareN(x4, 3, x7);
-            Curve25519Field.Multiply(x7, x3, x7);
-            uint[] x11 = x3;
-            Curve25519Field.SquareN(x7, 4, x11);
-            Curve25519Field.Multiply(x11, x4, x11);
-            uint[] x15 = x7;
-            Curve25519Field.SquareN(x11, 4, x15);
-            Curve25519Field.Multiply(x15, x4, x15);
-            uint[] x30 = x4;
-            Curve25519Field.SquareN(x15, 15, x30);
-            Curve25519Field.Multiply(x30, x15, x30);
-            uint[] x60 = x15;
-            Curve25519Field.SquareN(x30, 30, x60);
-            Curve25519Field.Multiply(x60, x30, x60);
-            uint[] x120 = x30;
-            Curve25519Field.SquareN(x60, 60, x120);
-            Curve25519Field.Multiply(x120, x60, x120);
-            uint[] x131 = x60;
-            Curve25519Field.SquareN(x120, 11, x131);
-            Curve25519Field.Multiply(x131, x11, x131);
-            uint[] x251 = x11;
-            Curve25519Field.SquareN(x131, 120, x251);
-            Curve25519Field.Multiply(x251, x120, x251);
-
-            uint[] t1 = x251;
-            Curve25519Field.Square(t1, t1);
-
-            uint[] t2 = x120;
-            Curve25519Field.Square(t1, t2);
-
-            if (Nat256.Eq(x1, t2))
-            {
-                return new Curve25519FieldElement(t1);
-            }
-
-            /*
-             * If the first guess is incorrect, we multiply by a precomputed power of 2 to get the second guess,
-             * which is ((4x)^(m + 1))/2 mod Q
-             */
-            Curve25519Field.Multiply(t1, PRECOMP_POW2, t1);
-
-            Curve25519Field.Square(t1, t2);
-
-            if (Nat256.Eq(x1, t2))
-            {
-                return new Curve25519FieldElement(t1);
-            }
-
-            return null;
-        }
-
-        public override bool Equals(object obj)
-        {
-            return Equals(obj as Curve25519FieldElement);
-        }
-
-        public override bool Equals(ECFieldElement other)
-        {
-            return Equals(other as Curve25519FieldElement);
-        }
-
-        public virtual bool Equals(Curve25519FieldElement other)
-        {
-            if (this == other)
-                return true;
-            if (null == other)
-                return false;
-            return Nat256.Eq(x, other.x);
-        }
-
-        public override int GetHashCode()
-        {
-            return Q.GetHashCode() ^ Arrays.GetHashCode(x, 0, 8);
-        }
-    }
-}
diff --git a/crypto/src/math/ec/custom/djb/Curve25519Point.cs b/crypto/src/math/ec/custom/djb/Curve25519Point.cs
deleted file mode 100644
index f61e28af8..000000000
--- a/crypto/src/math/ec/custom/djb/Curve25519Point.cs
+++ /dev/null
@@ -1,287 +0,0 @@
-using System;
-
-using Org.BouncyCastle.Math.Raw;
-
-namespace Org.BouncyCastle.Math.EC.Custom.Djb
-{
-    internal class Curve25519Point
-        : AbstractFpPoint
-    {
-        internal Curve25519Point(ECCurve curve, ECFieldElement x, ECFieldElement y)
-            : base(curve, x, y)
-        {
-        }
-
-        internal Curve25519Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
-            : base(curve, x, y, zs)
-        {
-        }
-
-        protected override ECPoint Detach()
-        {
-            return new Curve25519Point(null, AffineXCoord, AffineYCoord);
-        }
-
-        public override ECFieldElement GetZCoord(int index)
-        {
-            if (index == 1)
-            {
-                return GetJacobianModifiedW();
-            }
-
-            return base.GetZCoord(index);
-        }
-
-        public override ECPoint Add(ECPoint b)
-        {
-            if (this.IsInfinity)
-                return b;
-            if (b.IsInfinity)
-                return this;
-            if (this == b)
-                return Twice();
-
-            ECCurve curve = this.Curve;
-
-            Curve25519FieldElement X1 = (Curve25519FieldElement)this.RawXCoord, Y1 = (Curve25519FieldElement)this.RawYCoord,
-                Z1 = (Curve25519FieldElement)this.RawZCoords[0];
-            Curve25519FieldElement X2 = (Curve25519FieldElement)b.RawXCoord, Y2 = (Curve25519FieldElement)b.RawYCoord,
-                Z2 = (Curve25519FieldElement)b.RawZCoords[0];
-
-            uint c;
-            uint[] tt1 = Nat256.CreateExt();
-            uint[] t2 = Nat256.Create();
-            uint[] t3 = Nat256.Create();
-            uint[] t4 = Nat256.Create();
-
-            bool Z1IsOne = Z1.IsOne;
-            uint[] U2, S2;
-            if (Z1IsOne)
-            {
-                U2 = X2.x;
-                S2 = Y2.x;
-            }
-            else
-            {
-                S2 = t3;
-                Curve25519Field.Square(Z1.x, S2);
-
-                U2 = t2;
-                Curve25519Field.Multiply(S2, X2.x, U2);
-
-                Curve25519Field.Multiply(S2, Z1.x, S2);
-                Curve25519Field.Multiply(S2, Y2.x, S2);
-            }
-
-            bool Z2IsOne = Z2.IsOne;
-            uint[] U1, S1;
-            if (Z2IsOne)
-            {
-                U1 = X1.x;
-                S1 = Y1.x;
-            }
-            else
-            {
-                S1 = t4;
-                Curve25519Field.Square(Z2.x, S1);
-
-                U1 = tt1;
-                Curve25519Field.Multiply(S1, X1.x, U1);
-
-                Curve25519Field.Multiply(S1, Z2.x, S1);
-                Curve25519Field.Multiply(S1, Y1.x, S1);
-            }
-
-            uint[] H = Nat256.Create();
-            Curve25519Field.Subtract(U1, U2, H);
-
-            uint[] R = t2;
-            Curve25519Field.Subtract(S1, S2, R);
-
-            // Check if b == this or b == -this
-            if (Nat256.IsZero(H))
-            {
-                if (Nat256.IsZero(R))
-                {
-                    // this == b, i.e. this must be doubled
-                    return this.Twice();
-                }
-
-                // this == -b, i.e. the result is the point at infinity
-                return curve.Infinity;
-            }
-
-            uint[] HSquared = Nat256.Create();
-            Curve25519Field.Square(H, HSquared);
-
-            uint[] G = Nat256.Create();
-            Curve25519Field.Multiply(HSquared, H, G);
-
-            uint[] V = t3;
-            Curve25519Field.Multiply(HSquared, U1, V);
-
-            Curve25519Field.Negate(G, G);
-            Nat256.Mul(S1, G, tt1);
-
-            c = Nat256.AddBothTo(V, V, G);
-            Curve25519Field.Reduce27(c, G);
-
-            Curve25519FieldElement X3 = new Curve25519FieldElement(t4);
-            Curve25519Field.Square(R, X3.x);
-            Curve25519Field.Subtract(X3.x, G, X3.x);
-
-            Curve25519FieldElement Y3 = new Curve25519FieldElement(G);
-            Curve25519Field.Subtract(V, X3.x, Y3.x);
-            Curve25519Field.MultiplyAddToExt(Y3.x, R, tt1);
-            Curve25519Field.Reduce(tt1, Y3.x);
-
-            Curve25519FieldElement Z3 = new Curve25519FieldElement(H);
-            if (!Z1IsOne)
-            {
-                Curve25519Field.Multiply(Z3.x, Z1.x, Z3.x);
-            }
-            if (!Z2IsOne)
-            {
-                Curve25519Field.Multiply(Z3.x, Z2.x, Z3.x);
-            }
-
-            uint[] Z3Squared = (Z1IsOne && Z2IsOne) ? HSquared : null;
-
-            // TODO If the result will only be used in a subsequent addition, we don't need W3
-            Curve25519FieldElement W3 = CalculateJacobianModifiedW((Curve25519FieldElement)Z3, Z3Squared);
-
-            ECFieldElement[] zs = new ECFieldElement[] { Z3, W3 };
-
-            return new Curve25519Point(curve, X3, Y3, zs);
-        }
-
-        public override ECPoint Twice()
-        {
-            if (this.IsInfinity)
-                return this;
-
-            ECCurve curve = this.Curve;
-
-            ECFieldElement Y1 = this.RawYCoord;
-            if (Y1.IsZero)
-                return curve.Infinity;
-
-            return TwiceJacobianModified(true);
-        }
-
-        public override ECPoint TwicePlus(ECPoint b)
-        {
-            if (this == b)
-                return ThreeTimes();
-            if (this.IsInfinity)
-                return b;
-            if (b.IsInfinity)
-                return Twice();
-
-            ECFieldElement Y1 = this.RawYCoord;
-            if (Y1.IsZero)
-                return b;
-
-            return TwiceJacobianModified(false).Add(b);
-        }
-
-        public override ECPoint ThreeTimes()
-        {
-            if (this.IsInfinity || this.RawYCoord.IsZero)
-                return this;
-
-            return TwiceJacobianModified(false).Add(this);
-        }
-
-        public override ECPoint Negate()
-        {
-            if (IsInfinity)
-                return this;
-
-            return new Curve25519Point(Curve, RawXCoord, RawYCoord.Negate(), RawZCoords);
-        }
-
-        protected virtual Curve25519FieldElement CalculateJacobianModifiedW(Curve25519FieldElement Z, uint[] ZSquared)
-        {
-            Curve25519FieldElement a4 = (Curve25519FieldElement)this.Curve.A;
-            if (Z.IsOne)
-                return a4;
-
-            Curve25519FieldElement W = new Curve25519FieldElement();
-            if (ZSquared == null)
-            {
-                ZSquared = W.x;
-                Curve25519Field.Square(Z.x, ZSquared);
-            }
-            Curve25519Field.Square(ZSquared, W.x);
-            Curve25519Field.Multiply(W.x, a4.x, W.x);
-            return W;
-        }
-
-        protected virtual Curve25519FieldElement GetJacobianModifiedW()
-        {
-            ECFieldElement[] ZZ = this.RawZCoords;
-            Curve25519FieldElement W = (Curve25519FieldElement)ZZ[1];
-            if (W == null)
-            {
-                // NOTE: Rarely, TwicePlus will result in the need for a lazy W1 calculation here
-                ZZ[1] = W = CalculateJacobianModifiedW((Curve25519FieldElement)ZZ[0], null);
-            }
-            return W;
-        }
-
-        protected virtual Curve25519Point TwiceJacobianModified(bool calculateW)
-        {
-            Curve25519FieldElement X1 = (Curve25519FieldElement)this.RawXCoord, Y1 = (Curve25519FieldElement)this.RawYCoord,
-                Z1 = (Curve25519FieldElement)this.RawZCoords[0], W1 = GetJacobianModifiedW();
-
-            uint c;
-
-            uint[] M = Nat256.Create();
-            Curve25519Field.Square(X1.x, M);
-            c = Nat256.AddBothTo(M, M, M);
-            c += Nat256.AddTo(W1.x, M);
-            Curve25519Field.Reduce27(c, M);
-
-            uint[] _2Y1 = Nat256.Create();
-            Curve25519Field.Twice(Y1.x, _2Y1);
-
-            uint[] _2Y1Squared = Nat256.Create();
-            Curve25519Field.Multiply(_2Y1, Y1.x, _2Y1Squared);
-
-            uint[] S = Nat256.Create();
-            Curve25519Field.Multiply(_2Y1Squared, X1.x, S);
-            Curve25519Field.Twice(S, S);
-
-            uint[] _8T = Nat256.Create();
-            Curve25519Field.Square(_2Y1Squared, _8T);
-            Curve25519Field.Twice(_8T, _8T);
-
-            Curve25519FieldElement X3 = new Curve25519FieldElement(_2Y1Squared);
-            Curve25519Field.Square(M, X3.x);
-            Curve25519Field.Subtract(X3.x, S, X3.x);
-            Curve25519Field.Subtract(X3.x, S, X3.x);
-
-            Curve25519FieldElement Y3 = new Curve25519FieldElement(S);
-            Curve25519Field.Subtract(S, X3.x, Y3.x);
-            Curve25519Field.Multiply(Y3.x, M, Y3.x);
-            Curve25519Field.Subtract(Y3.x, _8T, Y3.x);
-
-            Curve25519FieldElement Z3 = new Curve25519FieldElement(_2Y1);
-            if (!Nat256.IsOne(Z1.x))
-            {
-                Curve25519Field.Multiply(Z3.x, Z1.x, Z3.x);
-            }
-
-            Curve25519FieldElement W3 = null;
-            if (calculateW)
-            {
-                W3 = new Curve25519FieldElement(_8T);
-                Curve25519Field.Multiply(W3.x, W1.x, W3.x);
-                Curve25519Field.Twice(W3.x, W3.x);
-            }
-
-            return new Curve25519Point(this.Curve, X3, Y3, new ECFieldElement[] { Z3, W3 });
-        }
-    }
-}
diff --git a/crypto/test/src/crypto/test/ECTest.cs b/crypto/test/src/crypto/test/ECTest.cs
index 18abb8df1..58dc75e2f 100644
--- a/crypto/test/src/crypto/test/ECTest.cs
+++ b/crypto/test/src/crypto/test/ECTest.cs
@@ -745,8 +745,19 @@ namespace Org.BouncyCastle.Crypto.Tests
         {
             SecureRandom random = new SecureRandom();
 
-            X9ECParameters x9 = CustomNamedCurves.GetByName("curve25519");
-            ECDomainParameters ec = new ECDomainParameters(x9.Curve, x9.G, x9.N, x9.H, x9.GetSeed());
+            // "curve25519" in short Weierstrass form
+            BigInteger q = BigInteger.One.ShiftLeft(255).Subtract(BigInteger.ValueOf(19));
+            BigInteger a = new BigInteger(1, Hex.DecodeStrict("2AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA984914A144"));
+            BigInteger b = new BigInteger(1, Hex.DecodeStrict("7B425ED097B425ED097B425ED097B425ED097B425ED097B4260B5E9C7710C864"));
+            BigInteger n = new BigInteger(1, Hex.DecodeStrict("1000000000000000000000000000000014DEF9DEA2F79CD65812631A5CF5D3ED"));
+            BigInteger h = BigInteger.ValueOf(8);
+
+            ECCurve curve = new FpCurve(q, a, b, n, h);
+            X9ECPoint G = new X9ECPoint(curve,
+                Hex.DecodeStrict("042AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD245A20AE19A1B8A086B4E01EDD2C7748D14C923D4D7E6D7C61B229E9C5A27ECED3D9"));
+
+            X9ECParameters x9 = new X9ECParameters(curve, G, n, h);
+            ECDomainParameters ec = new ECDomainParameters(x9);
 
             ECKeyPairGenerator kpg = new ECKeyPairGenerator();
             kpg.Init(new ECKeyGenerationParameters(ec, random));