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using System;
using Org.BouncyCastle.Math.Field;
using Org.BouncyCastle.Utilities.Encoders;
namespace Org.BouncyCastle.Math.EC.Custom.Sec
{
internal class SecP521R1Curve
: ECCurve
{
public static readonly BigInteger q = new BigInteger(1,
Hex.Decode("01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"));
private const int SecP521R1_DEFAULT_COORDS = COORD_JACOBIAN;
protected readonly SecP521R1Point m_infinity;
public SecP521R1Curve()
: base(FiniteFields.GetPrimeField(q))
{
this.m_infinity = new SecP521R1Point(this, null, null);
this.m_a = FromBigInteger(new BigInteger(1,
Hex.Decode("01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC")));
this.m_b = FromBigInteger(new BigInteger(1,
Hex.Decode("0051953EB9618E1C9A1F929A21A0B68540EEA2DA725B99B315F3B8B489918EF109E156193951EC7E937B1652C0BD3BB1BF073573DF883D2C34F1EF451FD46B503F00")));
this.m_order = new BigInteger(1, Hex.Decode("01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFA51868783BF2F966B7FCC0148F709A5D03BB5C9B8899C47AEBB6FB71E91386409"));
this.m_cofactor = BigInteger.One;
this.m_coord = SecP521R1_DEFAULT_COORDS;
}
protected override ECCurve CloneCurve()
{
return new SecP521R1Curve();
}
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 SecP521R1FieldElement(x);
}
protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, bool withCompression)
{
return new SecP521R1Point(this, x, y, withCompression);
}
protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
{
ECFieldElement x = FromBigInteger(X1);
ECFieldElement alpha = x.Square().Add(A).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 SecP521R1Point(this, x, beta, true);
}
}
}
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