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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.ECMultiplier;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.math.ec.GLVMultiplier;
import org.bouncycastle.math.ec.endo.GLVTypeBEndomorphism;
import org.bouncycastle.math.ec.endo.GLVTypeBParameters;
import org.bouncycastle.math.field.FiniteFields;
import org.bouncycastle.util.encoders.Hex;
public class SecP256K1Curve extends ECCurve
{
public static final BigInteger q = new BigInteger(1,
Hex.decode("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F"));
private static final int SECP256K1_DEFAULT_COORDS = COORD_JACOBIAN;
protected SecP256K1Point infinity;
public SecP256K1Curve()
{
super(FiniteFields.getPrimeField(q));
this.infinity = new SecP256K1Point(this, null, null);
this.a = fromBigInteger(ECConstants.ZERO);
this.b = fromBigInteger(BigInteger.valueOf(7));
this.order = new BigInteger(1, Hex.decode("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141"));
this.cofactor = BigInteger.valueOf(1);
this.coord = SECP256K1_DEFAULT_COORDS;
}
protected ECCurve cloneCurve()
{
return new SecP256K1Curve();
}
public boolean supportsCoordinateSystem(int coord)
{
switch (coord)
{
case COORD_JACOBIAN:
return true;
default:
return false;
}
}
protected ECMultiplier createDefaultMultiplier()
{
GLVTypeBParameters p = new GLVTypeBParameters(
fromBigInteger(new BigInteger("7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee", 16)),
new BigInteger("5363ad4cc05c30e0a5261c028812645a122e22ea20816678df02967c1b23bd72", 16),
new BigInteger[]{
new BigInteger("3086d221a7d46bcde86c90e49284eb15", 16),
new BigInteger("-e4437ed6010e88286f547fa90abfe4c3", 16) },
new BigInteger[]{
new BigInteger("114ca50f7a8e2f3f657c1108d9d44cfd8", 16),
new BigInteger("3086d221a7d46bcde86c90e49284eb15", 16) },
new BigInteger("c21b48869f51af37a1b243924a13ac55", 16),
new BigInteger("3910dfb58043a20a1bd51fea42aff9311", 16),
258);
return new GLVMultiplier(this, new GLVTypeBEndomorphism(p));
}
public BigInteger getQ()
{
return q;
}
public int getFieldSize()
{
return q.bitLength();
}
public ECFieldElement fromBigInteger(BigInteger x)
{
return new SecP256K1FieldElement(x);
}
protected ECPoint createRawPoint(ECFieldElement x, ECFieldElement y, boolean withCompression)
{
return new SecP256K1Point(this, x, y, withCompression);
}
protected ECPoint createRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs, boolean withCompression)
{
return new SecP256K1Point(this, x, y, zs, withCompression);
}
protected ECPoint decompressPoint(int yTilde, BigInteger X1)
{
ECFieldElement x = fromBigInteger(X1);
ECFieldElement alpha = x.square().multiply(x).add(getB());
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 SecP256K1Point(this, x, beta, true);
}
public ECPoint getInfinity()
{
return infinity;
}
}
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