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package org.bouncycastle.math.ec.custom.sec;
import java.math.BigInteger;
import org.bouncycastle.math.ec.ECConstants;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.math.field.FiniteFields;
import org.bouncycastle.util.encoders.Hex;
public class SecP256R1Curve extends ECCurve
{
public static final BigInteger q = new BigInteger(1,
Hex.decode("FFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFF"));
public static final BigInteger r = ECConstants.ONE.shiftLeft(256).subtract(q);
private static final int SecP256R1_DEFAULT_COORDS = COORD_JACOBIAN;
protected SecP256R1Point infinity;
public SecP256R1Curve()
{
super(FiniteFields.getPrimeField(q));
this.infinity = new SecP256R1Point(this, null, null);
this.a = fromBigInteger(new BigInteger(1,
Hex.decode("FFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFC")));
this.b = fromBigInteger(new BigInteger(1,
Hex.decode("5AC635D8AA3A93E7B3EBBD55769886BC651D06B0CC53B0F63BCE3C3E27D2604B")));
this.order = new BigInteger(1, Hex.decode("FFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551"));
this.cofactor = BigInteger.valueOf(1);
this.coord = SecP256R1_DEFAULT_COORDS;
}
protected ECCurve cloneCurve()
{
return new SecP256R1Curve();
}
public boolean supportsCoordinateSystem(int coord)
{
switch (coord)
{
case COORD_JACOBIAN:
return true;
default:
return false;
}
}
public BigInteger getQ()
{
return q;
}
public int getFieldSize()
{
return q.bitLength();
}
public ECFieldElement fromBigInteger(BigInteger x)
{
return new SecP256R1FieldElement(x);
}
protected ECPoint createRawPoint(ECFieldElement x, ECFieldElement y, boolean withCompression)
{
return new SecP256R1Point(this, x, y, withCompression);
}
protected 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 RuntimeException("Invalid point compression");
}
if (beta.testBitZero() != (yTilde == 1))
{
// Use the other root
beta = beta.negate();
}
return new SecP256R1Point(this, x, beta, true);
}
public ECPoint getInfinity()
{
return infinity;
}
}
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