diff --git a/Crypto/src/asn1/x9/X9Curve.cs b/Crypto/src/asn1/x9/X9Curve.cs
new file mode 100644
index 000000000..b92e7b3b5
--- /dev/null
+++ b/Crypto/src/asn1/x9/X9Curve.cs
@@ -0,0 +1,147 @@
+using System;
+
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Math.EC;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Asn1.X9
+{
+ /**
+ * ASN.1 def for Elliptic-Curve Curve structure. See
+ * X9.62, for further details.
+ */
+ public class X9Curve
+ : Asn1Encodable
+ {
+ private readonly ECCurve curve;
+ private readonly byte[] seed;
+ private readonly DerObjectIdentifier fieldIdentifier;
+
+ public X9Curve(
+ ECCurve curve)
+ : this(curve, null)
+ {
+ this.curve = curve;
+ }
+
+ public X9Curve(
+ ECCurve curve,
+ byte[] seed)
+ {
+ if (curve == null)
+ throw new ArgumentNullException("curve");
+
+ this.curve = curve;
+ this.seed = Arrays.Clone(seed);
+
+ if (curve is FpCurve)
+ {
+ this.fieldIdentifier = X9ObjectIdentifiers.PrimeField;
+ }
+ else if (curve is F2mCurve)
+ {
+ this.fieldIdentifier = X9ObjectIdentifiers.CharacteristicTwoField;
+ }
+ else
+ {
+ throw new ArgumentException("This type of ECCurve is not implemented");
+ }
+ }
+
+ public X9Curve(
+ X9FieldID fieldID,
+ Asn1Sequence seq)
+ {
+ if (fieldID == null)
+ throw new ArgumentNullException("fieldID");
+ if (seq == null)
+ throw new ArgumentNullException("seq");
+
+ this.fieldIdentifier = fieldID.Identifier;
+
+ if (fieldIdentifier.Equals(X9ObjectIdentifiers.PrimeField))
+ {
+ BigInteger q = ((DerInteger) fieldID.Parameters).Value;
+ X9FieldElement x9A = new X9FieldElement(q, (Asn1OctetString) seq[0]);
+ X9FieldElement x9B = new X9FieldElement(q, (Asn1OctetString) seq[1]);
+ curve = new FpCurve(q, x9A.Value.ToBigInteger(), x9B.Value.ToBigInteger());
+ }
+ else
+ {
+ if (fieldIdentifier.Equals(X9ObjectIdentifiers.CharacteristicTwoField))
+ {
+ // Characteristic two field
+ DerSequence parameters = (DerSequence)fieldID.Parameters;
+ int m = ((DerInteger)parameters[0]).Value.IntValue;
+ DerObjectIdentifier representation
+ = (DerObjectIdentifier)parameters[1];
+
+ int k1 = 0;
+ int k2 = 0;
+ int k3 = 0;
+ if (representation.Equals(X9ObjectIdentifiers.TPBasis))
+ {
+ // Trinomial basis representation
+ k1 = ((DerInteger)parameters[2]).Value.IntValue;
+ }
+ else
+ {
+ // Pentanomial basis representation
+ DerSequence pentanomial = (DerSequence) parameters[2];
+ k1 = ((DerInteger) pentanomial[0]).Value.IntValue;
+ k2 = ((DerInteger) pentanomial[1]).Value.IntValue;
+ k3 = ((DerInteger) pentanomial[2]).Value.IntValue;
+ }
+ X9FieldElement x9A = new X9FieldElement(m, k1, k2, k3, (Asn1OctetString)seq[0]);
+ X9FieldElement x9B = new X9FieldElement(m, k1, k2, k3, (Asn1OctetString)seq[1]);
+ // TODO Is it possible to get the order (n) and cofactor(h) too?
+ curve = new F2mCurve(m, k1, k2, k3, x9A.Value.ToBigInteger(), x9B.Value.ToBigInteger());
+ }
+ }
+
+ if (seq.Count == 3)
+ {
+ seed = ((DerBitString) seq[2]).GetBytes();
+ }
+ }
+
+ public ECCurve Curve
+ {
+ get { return curve; }
+ }
+
+ public byte[] GetSeed()
+ {
+ return Arrays.Clone(seed);
+ }
+
+ /**
+ * Produce an object suitable for an Asn1OutputStream.
+ * <pre>
+ * Curve ::= Sequence {
+ * a FieldElement,
+ * b FieldElement,
+ * seed BIT STRING OPTIONAL
+ * }
+ * </pre>
+ */
+ public override Asn1Object ToAsn1Object()
+ {
+ Asn1EncodableVector v = new Asn1EncodableVector();
+
+ if (fieldIdentifier.Equals(X9ObjectIdentifiers.PrimeField)
+ || fieldIdentifier.Equals(X9ObjectIdentifiers.CharacteristicTwoField))
+ {
+ v.Add(new X9FieldElement(curve.A).ToAsn1Object());
+ v.Add(new X9FieldElement(curve.B).ToAsn1Object());
+ }
+
+ if (seed != null)
+ {
+ v.Add(new DerBitString(seed));
+ }
+
+ return new DerSequence(v);
+ }
+ }
+}
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