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using System;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
namespace Org.BouncyCastle.Asn1.X9
{
/**
* ASN.1 def for Elliptic-Curve ECParameters structure. See
* X9.62, for further details.
*/
public class X9ECParameters
: Asn1Encodable
{
private X9FieldID fieldID;
private ECCurve curve;
private ECPoint g;
private BigInteger n;
private BigInteger h;
private byte[] seed;
public X9ECParameters(
Asn1Sequence seq)
{
if (!(seq[0] is DerInteger)
|| !((DerInteger) seq[0]).Value.Equals(BigInteger.One))
{
throw new ArgumentException("bad version in X9ECParameters");
}
X9Curve x9c = null;
if (seq[2] is X9Curve)
{
x9c = (X9Curve) seq[2];
}
else
{
x9c = new X9Curve(
new X9FieldID(
(Asn1Sequence) seq[1]),
(Asn1Sequence) seq[2]);
}
this.curve = x9c.Curve;
if (seq[3] is X9ECPoint)
{
this.g = ((X9ECPoint) seq[3]).Point;
}
else
{
this.g = new X9ECPoint(curve, (Asn1OctetString) seq[3]).Point;
}
this.n = ((DerInteger) seq[4]).Value;
this.seed = x9c.GetSeed();
if (seq.Count == 6)
{
this.h = ((DerInteger) seq[5]).Value;
}
}
public X9ECParameters(
ECCurve curve,
ECPoint g,
BigInteger n)
: this(curve, g, n, BigInteger.One, null)
{
}
public X9ECParameters(
ECCurve curve,
ECPoint g,
BigInteger n,
BigInteger h)
: this(curve, g, n, h, null)
{
}
public X9ECParameters(
ECCurve curve,
ECPoint g,
BigInteger n,
BigInteger h,
byte[] seed)
{
this.curve = curve;
this.g = g;
this.n = n;
this.h = h;
this.seed = seed;
if (curve is FpCurve)
{
this.fieldID = new X9FieldID(((FpCurve) curve).Q);
}
else if (curve is F2mCurve)
{
F2mCurve curveF2m = (F2mCurve) curve;
this.fieldID = new X9FieldID(curveF2m.M, curveF2m.K1,
curveF2m.K2, curveF2m.K3);
}
}
public ECCurve Curve
{
get { return curve; }
}
public ECPoint G
{
get { return g; }
}
public BigInteger N
{
get { return n; }
}
public BigInteger H
{
get
{
if (h == null)
{
// TODO - this should be calculated, it will cause issues with custom curves.
return BigInteger.One;
}
return h;
}
}
public byte[] GetSeed()
{
return seed;
}
/**
* Produce an object suitable for an Asn1OutputStream.
* <pre>
* ECParameters ::= Sequence {
* version Integer { ecpVer1(1) } (ecpVer1),
* fieldID FieldID {{FieldTypes}},
* curve X9Curve,
* base X9ECPoint,
* order Integer,
* cofactor Integer OPTIONAL
* }
* </pre>
*/
public override Asn1Object ToAsn1Object()
{
Asn1EncodableVector v = new Asn1EncodableVector(
new DerInteger(1),
fieldID,
new X9Curve(curve, seed),
new X9ECPoint(g),
new DerInteger(n));
if (h != null)
{
v.Add(new DerInteger(h));
}
return new DerSequence(v);
}
}
}
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