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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