diff --git a/crypto/src/crypto/ec/CustomNamedCurves.cs b/crypto/src/crypto/ec/CustomNamedCurves.cs
index 3bc7b16cc..7d6b00339 100644
--- a/crypto/src/crypto/ec/CustomNamedCurves.cs
+++ b/crypto/src/crypto/ec/CustomNamedCurves.cs
@@ -72,6 +72,27 @@ namespace Org.BouncyCastle.Crypto.EC
}
/*
+ * secp224k1
+ */
+ internal class Secp224k1Holder
+ : X9ECParametersHolder
+ {
+ private Secp224k1Holder() { }
+
+ internal static readonly X9ECParametersHolder Instance = new Secp224k1Holder();
+
+ protected override X9ECParameters CreateParameters()
+ {
+ byte[] S = null;
+ ECCurve curve = ConfigureCurve(new SecP224K1Curve());
+ ECPoint G = curve.DecodePoint(Hex.Decode("04"
+ + "A1455B334DF099DF30FC28A169A467E9E47075A90F7E650EB6B7A45C"
+ + "7E089FED7FBA344282CAFBD6F7E319F7C0B0BD59E2CA4BDB556D61A5"));
+ return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
+ }
+ }
+
+ /*
* secp224r1
*/
internal class Secp224r1Holder
@@ -170,6 +191,7 @@ namespace Org.BouncyCastle.Crypto.EC
{
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);
diff --git a/crypto/src/math/ec/custom/sec/SecP224K1Curve.cs b/crypto/src/math/ec/custom/sec/SecP224K1Curve.cs
new file mode 100644
index 000000000..5d82eaed8
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecP224K1Curve.cs
@@ -0,0 +1,93 @@
+using System;
+
+using Org.BouncyCastle.Math.Field;
+using Org.BouncyCastle.Utilities.Encoders;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+ internal class SecP224K1Curve
+ : ECCurve
+ {
+ public static readonly BigInteger q = new BigInteger(1,
+ Hex.Decode("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFE56D"));
+
+ private const int SECP224K1_DEFAULT_COORDS = COORD_JACOBIAN;
+
+ protected readonly SecP224K1Point m_infinity;
+
+ public SecP224K1Curve()
+ : base(FiniteFields.GetPrimeField(q))
+ {
+ this.m_infinity = new SecP224K1Point(this, null, null);
+
+ this.m_a = FromBigInteger(BigInteger.Zero);
+ this.m_b = FromBigInteger(BigInteger.ValueOf(5));
+ this.m_order = new BigInteger(1, Hex.Decode("010000000000000000000000000001DCE8D2EC6184CAF0A971769FB1F7"));
+ this.m_cofactor = BigInteger.One;
+ this.m_coord = SECP224K1_DEFAULT_COORDS;
+ }
+
+ protected override ECCurve CloneCurve()
+ {
+ return new SecP224K1Curve();
+ }
+
+ public override bool SupportsCoordinateSystem(int coord)
+ {
+ switch (coord)
+ {
+ case COORD_JACOBIAN:
+ 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 SecP224K1FieldElement(x);
+ }
+
+ protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, bool withCompression)
+ {
+ return new SecP224K1Point(this, x, y, withCompression);
+ }
+
+ protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
+ {
+ ECFieldElement x = FromBigInteger(X1);
+ ECFieldElement alpha = x.Square().Multiply(x).Add(B);
+ ECFieldElement beta = alpha.Sqrt();
+
+ //
+ // if we can't find a sqrt we haven't got a point on the
+ // curve - run!
+ //
+ if (beta == null)
+ throw new ArithmeticException("Invalid point compression");
+
+ if (beta.TestBitZero() != (yTilde == 1))
+ {
+ // Use the other root
+ beta = beta.Negate();
+ }
+
+ return new SecP224K1Point(this, x, beta, true);
+ }
+ }
+}
diff --git a/crypto/src/math/ec/custom/sec/SecP224K1Field.cs b/crypto/src/math/ec/custom/sec/SecP224K1Field.cs
new file mode 100644
index 000000000..edc938d22
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecP224K1Field.cs
@@ -0,0 +1,150 @@
+using System;
+using System.Diagnostics;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+ internal class SecP224K1Field
+ {
+ // 2^224 - 2^32 - 2^12 - 2^11 - 2^9 - 2^7 - 2^4 - 2 - 1
+ internal static readonly uint[] P = new uint[]{ 0xFFFFE56D, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
+ 0xFFFFFFFF };
+ private const uint P6 = 0xFFFFFFFF;
+ private static readonly uint[] PExt = new uint[]{ 0x02C23069, 0x00003526, 0x00000001, 0x00000000, 0x00000000,
+ 0x00000000, 0x00000000, 0xFFFFCADA, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+ private const uint PExt13 = 0xFFFFFFFF;
+ private const ulong PInv = 0x0000000100001A93L;
+ private const uint PInv33 = 0x1A93;
+
+ public static void Add(uint[] x, uint[] y, uint[] z)
+ {
+ uint c = Nat224.Add(x, y, z);
+ if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+ {
+ Nat224.AddDWord(PInv, z, 0);
+ }
+ }
+
+ public static void AddExt(uint[] xx, uint[] yy, uint[] zz)
+ {
+ uint c = Nat224.AddExt(xx, yy, zz);
+ if (c != 0 || (zz[13] == PExt13 && Nat224.GteExt(zz, PExt)))
+ {
+ Nat224.SubExt(zz, PExt, zz);
+ }
+ }
+
+ public static void AddOne(uint[] x, uint[] z)
+ {
+ Array.Copy(x, 0, z, 0, 8);
+ uint c = Nat224.Inc(z, 0);
+ if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+ {
+ Nat224.AddDWord(PInv, z, 0);
+ }
+ }
+
+ public static uint[] FromBigInteger(BigInteger x)
+ {
+ uint[] z = Nat224.FromBigInteger(x);
+ if (z[6] == P6 && Nat224.Gte(z, P))
+ {
+ Nat224.AddDWord(PInv, z, 0);
+ }
+ return z;
+ }
+
+ public static void Half(uint[] x, uint[] z)
+ {
+ if ((x[0] & 1) == 0)
+ {
+ Nat224.ShiftDownBit(x, 0, z);
+ }
+ else
+ {
+ uint c = Nat224.Add(x, P, z);
+ Nat224.ShiftDownBit(z, c, z);
+ }
+ }
+
+ public static void Multiply(uint[] x, uint[] y, uint[] z)
+ {
+ uint[] tt = Nat224.CreateExt();
+ Nat224.Mul(x, y, tt);
+ Reduce(tt, z);
+ }
+
+ public static void Negate(uint[] x, uint[] z)
+ {
+ if (Nat224.IsZero(x))
+ {
+ Nat224.Zero(z);
+ }
+ else
+ {
+ Nat224.Sub(P, x, z);
+ }
+ }
+
+ public static void Reduce(uint[] xx, uint[] z)
+ {
+ ulong c = Nat224.Mul33Add(PInv33, xx, 7, xx, 0, z, 0);
+ c = Nat224.Mul33DWordAdd(PInv33, c, z, 0);
+
+ Debug.Assert(c == 0 || c == 1);
+
+ if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+ {
+ Nat224.AddDWord(PInv, z, 0);
+ }
+ }
+
+ public static void Square(uint[] x, uint[] z)
+ {
+ uint[] tt = Nat224.CreateExt();
+ Nat224.Square(x, tt);
+ Reduce(tt, z);
+ }
+
+ public static void SquareN(uint[] x, int n, uint[] z)
+ {
+ Debug.Assert(n > 0);
+
+ uint[] tt = Nat224.CreateExt();
+ Nat224.Square(x, tt);
+ Reduce(tt, z);
+
+ while (--n > 0)
+ {
+ Nat224.Square(z, tt);
+ Reduce(tt, z);
+ }
+ }
+
+ public static void Subtract(uint[] x, uint[] y, uint[] z)
+ {
+ int c = Nat224.Sub(x, y, z);
+ if (c != 0)
+ {
+ Nat224.SubDWord(PInv, z);
+ }
+ }
+
+ public static void SubtractExt(uint[] xx, uint[] yy, uint[] zz)
+ {
+ int c = Nat224.SubExt(xx, yy, zz);
+ if (c != 0)
+ {
+ Nat224.AddExt(zz, PExt, zz);
+ }
+ }
+
+ public static void Twice(uint[] x, uint[] z)
+ {
+ uint c = Nat224.ShiftUpBit(x, 0, z);
+ if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+ {
+ Nat224.AddDWord(PInv, z, 0);
+ }
+ }
+ }
+}
diff --git a/crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs
new file mode 100644
index 000000000..cd9426769
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs
@@ -0,0 +1,156 @@
+using System;
+using System.Diagnostics;
+
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+ internal class SecP224K1FieldElement
+ : ECFieldElement
+ {
+ public static readonly BigInteger Q = SecP224K1Curve.q;
+
+ protected internal readonly uint[] x;
+
+ public SecP224K1FieldElement(BigInteger x)
+ {
+ if (x == null || x.SignValue < 0 || x.CompareTo(Q) >= 0)
+ throw new ArgumentException("value invalid for SecP224K1FieldElement", "x");
+
+ this.x = SecP224K1Field.FromBigInteger(x);
+ }
+
+ public SecP224K1FieldElement()
+ {
+ this.x = Nat224.Create();
+ }
+
+ protected internal SecP224K1FieldElement(uint[] x)
+ {
+ this.x = x;
+ }
+
+ public override bool IsZero
+ {
+ get { return Nat224.IsZero(x); }
+ }
+
+ public override bool IsOne
+ {
+ get { return Nat224.IsOne(x); }
+ }
+
+ public override bool TestBitZero()
+ {
+ return Nat224.GetBit(x, 0) == 1;
+ }
+
+ public override BigInteger ToBigInteger()
+ {
+ return Nat224.ToBigInteger(x);
+ }
+
+ public override string FieldName
+ {
+ get { return "SecP224K1Field"; }
+ }
+
+ public override int FieldSize
+ {
+ get { return Q.BitLength; }
+ }
+
+ public override ECFieldElement Add(ECFieldElement b)
+ {
+ uint[] z = Nat224.Create();
+ SecP224K1Field.Add(x, ((SecP224K1FieldElement)b).x, z);
+ return new SecP224K1FieldElement(z);
+ }
+
+ public override ECFieldElement AddOne()
+ {
+ uint[] z = Nat224.Create();
+ SecP224K1Field.AddOne(x, z);
+ return new SecP224K1FieldElement(z);
+ }
+
+ public override ECFieldElement Subtract(ECFieldElement b)
+ {
+ uint[] z = Nat224.Create();
+ SecP224K1Field.Subtract(x, ((SecP224K1FieldElement)b).x, z);
+ return new SecP224K1FieldElement(z);
+ }
+
+ public override ECFieldElement Multiply(ECFieldElement b)
+ {
+ uint[] z = Nat224.Create();
+ SecP224K1Field.Multiply(x, ((SecP224K1FieldElement)b).x, z);
+ return new SecP224K1FieldElement(z);
+ }
+
+ public override ECFieldElement Divide(ECFieldElement b)
+ {
+ //return Multiply(b.Invert());
+ uint[] z = Nat224.Create();
+ Mod.Invert(SecP224K1Field.P, ((SecP224K1FieldElement)b).x, z);
+ SecP224K1Field.Multiply(z, x, z);
+ return new SecP224K1FieldElement(z);
+ }
+
+ public override ECFieldElement Negate()
+ {
+ uint[] z = Nat224.Create();
+ SecP224K1Field.Negate(x, z);
+ return new SecP224K1FieldElement(z);
+ }
+
+ public override ECFieldElement Square()
+ {
+ uint[] z = Nat224.Create();
+ SecP224K1Field.Square(x, z);
+ return new SecP224K1FieldElement(z);
+ }
+
+ public override ECFieldElement Invert()
+ {
+ //return new SecP224K1FieldElement(ToBigInteger().ModInverse(Q));
+ uint[] z = Nat224.Create();
+ Mod.Invert(SecP224K1Field.P, x, z);
+ return new SecP224K1FieldElement(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()
+ {
+ ECFieldElement root = new FpFieldElement(Q, ToBigInteger()).Sqrt();
+ return root == null ? null : new SecP224K1FieldElement(root.ToBigInteger());
+ }
+
+ public override bool Equals(object obj)
+ {
+ return Equals(obj as SecP224K1FieldElement);
+ }
+
+ public override bool Equals(ECFieldElement other)
+ {
+ return Equals(other as SecP224K1FieldElement);
+ }
+
+ public virtual bool Equals(SecP224K1FieldElement other)
+ {
+ if (this == other)
+ return true;
+ if (null == other)
+ return false;
+ return Arrays.AreEqual(x, other.x);
+ }
+
+ public override int GetHashCode()
+ {
+ return Q.GetHashCode() ^ Arrays.GetHashCode(x);
+ }
+ }
+}
diff --git a/crypto/src/math/ec/custom/sec/SecP224K1Point.cs b/crypto/src/math/ec/custom/sec/SecP224K1Point.cs
new file mode 100644
index 000000000..f85c64981
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecP224K1Point.cs
@@ -0,0 +1,276 @@
+using System;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+ internal class SecP224K1Point
+ : ECPointBase
+ {
+ /**
+ * Create a point which encodes with point compression.
+ *
+ * @param curve
+ * the curve to use
+ * @param x
+ * affine x co-ordinate
+ * @param y
+ * affine y co-ordinate
+ *
+ * @deprecated Use ECCurve.createPoint to construct points
+ */
+ public SecP224K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y)
+ : this(curve, x, y, false)
+ {
+ }
+
+ /**
+ * Create a point that encodes with or without point compresion.
+ *
+ * @param curve
+ * the curve to use
+ * @param x
+ * affine x co-ordinate
+ * @param y
+ * affine y co-ordinate
+ * @param withCompression
+ * if true encode with point compression
+ *
+ * @deprecated per-point compression property will be removed, refer
+ * {@link #getEncoded(bool)}
+ */
+ public SecP224K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, bool withCompression)
+ : base(curve, x, y, withCompression)
+ {
+ if ((x == null) != (y == null))
+ throw new ArgumentException("Exactly one of the field elements is null");
+ }
+
+ internal SecP224K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs,
+ bool withCompression)
+ : base(curve, x, y, zs, withCompression)
+ {
+ }
+
+ protected override ECPoint Detach()
+ {
+ return new SecP224K1Point(null, AffineXCoord, AffineYCoord);
+ }
+
+ protected internal override bool CompressionYTilde
+ {
+ get { return this.AffineYCoord.TestBitZero(); }
+ }
+
+ 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;
+
+ SecP224K1FieldElement X1 = (SecP224K1FieldElement)this.RawXCoord, Y1 = (SecP224K1FieldElement)this.RawYCoord;
+ SecP224K1FieldElement X2 = (SecP224K1FieldElement)b.RawXCoord, Y2 = (SecP224K1FieldElement)b.RawYCoord;
+
+ SecP224K1FieldElement Z1 = (SecP224K1FieldElement)this.RawZCoords[0];
+ SecP224K1FieldElement Z2 = (SecP224K1FieldElement)b.RawZCoords[0];
+
+ uint[] tt1 = Nat224.CreateExt();
+ uint[] tt2 = Nat224.CreateExt();
+ uint[] t3 = Nat224.Create();
+ uint[] t4 = Nat224.Create();
+
+ bool Z1IsOne = Z1.IsOne;
+ uint[] U2, S2;
+ if (Z1IsOne)
+ {
+ U2 = X2.x;
+ S2 = Y2.x;
+ }
+ else
+ {
+ S2 = t3;
+ SecP224K1Field.Square(Z1.x, S2);
+
+ U2 = tt2;
+ SecP224K1Field.Multiply(S2, X2.x, U2);
+
+ SecP224K1Field.Multiply(S2, Z1.x, S2);
+ SecP224K1Field.Multiply(S2, Y2.x, S2);
+ }
+
+ bool Z2IsOne = Z2.IsOne;
+ uint[] U1, S1;
+ if (Z2IsOne)
+ {
+ U1 = X1.x;
+ S1 = Y1.x;
+ }
+ else
+ {
+ S1 = t4;
+ SecP224K1Field.Square(Z2.x, S1);
+
+ U1 = tt1;
+ SecP224K1Field.Multiply(S1, X1.x, U1);
+
+ SecP224K1Field.Multiply(S1, Z2.x, S1);
+ SecP224K1Field.Multiply(S1, Y1.x, S1);
+ }
+
+ uint[] H = Nat224.Create();
+ SecP224K1Field.Subtract(U1, U2, H);
+
+ uint[] R = tt2;
+ SecP224K1Field.Subtract(S1, S2, R);
+
+ // Check if b == this or b == -this
+ if (Nat224.IsZero(H))
+ {
+ if (Nat224.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 = t3;
+ SecP224K1Field.Square(H, HSquared);
+
+ uint[] G = Nat224.Create();
+ SecP224K1Field.Multiply(HSquared, H, G);
+
+ uint[] V = t3;
+ SecP224K1Field.Multiply(HSquared, U1, V);
+
+ Nat224.Mul(S1, G, tt1);
+
+ SecP224K1FieldElement X3 = new SecP224K1FieldElement(t4);
+ SecP224K1Field.Square(R, X3.x);
+ SecP224K1Field.Add(X3.x, G, X3.x);
+ SecP224K1Field.Subtract(X3.x, V, X3.x);
+ SecP224K1Field.Subtract(X3.x, V, X3.x);
+
+ SecP224K1FieldElement Y3 = new SecP224K1FieldElement(G);
+ SecP224K1Field.Subtract(V, X3.x, Y3.x);
+ Nat224.Mul(Y3.x, R, tt2);
+ SecP224K1Field.SubtractExt(tt2, tt1, tt2);
+ SecP224K1Field.Reduce(tt2, Y3.x);
+
+ SecP224K1FieldElement Z3 = new SecP224K1FieldElement(H);
+ if (!Z1IsOne)
+ {
+ SecP224K1Field.Multiply(Z3.x, Z1.x, Z3.x);
+ }
+ if (!Z2IsOne)
+ {
+ SecP224K1Field.Multiply(Z3.x, Z2.x, Z3.x);
+ }
+
+ ECFieldElement[] zs = new ECFieldElement[] { Z3 };
+
+ return new SecP224K1Point(curve, X3, Y3, zs, IsCompressed);
+ }
+
+ public override ECPoint Twice()
+ {
+ if (this.IsInfinity)
+ return this;
+
+ ECCurve curve = this.Curve;
+
+ SecP224K1FieldElement Y1 = (SecP224K1FieldElement)this.RawYCoord;
+ if (Y1.IsZero)
+ return curve.Infinity;
+
+ SecP224K1FieldElement X1 = (SecP224K1FieldElement)this.RawXCoord, Z1 = (SecP224K1FieldElement)this.RawZCoords[0];
+
+ uint[] Y1Squared = Nat224.Create();
+ SecP224K1Field.Square(Y1.x, Y1Squared);
+
+ uint[] T = Nat224.Create();
+ SecP224K1Field.Square(Y1Squared, T);
+
+ uint[] t1 = Nat224.Create();
+ SecP224K1Field.Square(X1.x, t1);
+
+ uint[] M = Nat224.Create();
+ SecP224K1Field.Twice(t1, M);
+ SecP224K1Field.Add(M, t1, M);
+
+ uint[] S = Y1Squared;
+ SecP224K1Field.Multiply(Y1Squared, X1.x, S);
+ SecP224K1Field.Twice(S, S);
+ SecP224K1Field.Twice(S, S);
+
+ SecP224K1Field.Twice(T, t1);
+ SecP224K1Field.Twice(t1, t1);
+ SecP224K1Field.Twice(t1, t1);
+
+ SecP224K1FieldElement X3 = new SecP224K1FieldElement(T);
+ SecP224K1Field.Square(M, X3.x);
+ SecP224K1Field.Subtract(X3.x, S, X3.x);
+ SecP224K1Field.Subtract(X3.x, S, X3.x);
+
+ SecP224K1FieldElement Y3 = new SecP224K1FieldElement(S);
+ SecP224K1Field.Subtract(S, X3.x, Y3.x);
+ SecP224K1Field.Multiply(Y3.x, M, Y3.x);
+ SecP224K1Field.Subtract(Y3.x, t1, Y3.x);
+
+ SecP224K1FieldElement Z3 = new SecP224K1FieldElement(M);
+ SecP224K1Field.Twice(Y1.x, Z3.x);
+ if (!Z1.IsOne)
+ {
+ SecP224K1Field.Multiply(Z3.x, Z1.x, Z3.x);
+ }
+
+ return new SecP224K1Point(curve, X3, Y3, new ECFieldElement[] { Z3 }, IsCompressed);
+ }
+
+ 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 Twice().Add(b);
+ }
+
+ public override ECPoint ThreeTimes()
+ {
+ if (this.IsInfinity || this.RawYCoord.IsZero)
+ return this;
+
+ // NOTE: Be careful about recursions between TwicePlus and ThreeTimes
+ return Twice().Add(this);
+ }
+
+ public override ECPoint Subtract(ECPoint b)
+ {
+ if (b.IsInfinity)
+ return this;
+
+ return Add(b.Negate());
+ }
+
+ public override ECPoint Negate()
+ {
+ if (IsInfinity)
+ return this;
+
+ return new SecP224K1Point(Curve, RawXCoord, RawYCoord.Negate(), RawZCoords, IsCompressed);
+ }
+ }
+}
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