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The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 and up. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.

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package org.bouncycastle.math.ec.custom.sec;

import java.math.BigInteger;
import java.security.SecureRandom;

import org.bouncycastle.math.ec.AbstractECLookupTable;
import org.bouncycastle.math.ec.ECConstants;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.ec.ECLookupTable;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.math.raw.Nat192;
import org.bouncycastle.util.encoders.Hex;

public class SecP192K1Curve extends ECCurve.AbstractFp
{
    public static final BigInteger q = SecP192K1FieldElement.Q;

    private static final int SECP192K1_DEFAULT_COORDS = COORD_JACOBIAN;
    private static final ECFieldElement[] SECP192K1_AFFINE_ZS = new ECFieldElement[] { new SecP192K1FieldElement(ECConstants.ONE) }; 

    protected SecP192K1Point infinity;

    public SecP192K1Curve()
    {
        super(q);

        this.infinity = new SecP192K1Point(this, null, null);

        this.a = fromBigInteger(ECConstants.ZERO);
        this.b = fromBigInteger(BigInteger.valueOf(3));
        this.order = new BigInteger(1, Hex.decodeStrict("FFFFFFFFFFFFFFFFFFFFFFFE26F2FC170F69466A74DEFD8D"));
        this.cofactor = BigInteger.valueOf(1);

        this.coord = SECP192K1_DEFAULT_COORDS;
    }

    protected ECCurve cloneCurve()
    {
        return new SecP192K1Curve();
    }

    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 SecP192K1FieldElement(x);
    }

    protected ECPoint createRawPoint(ECFieldElement x, ECFieldElement y)
    {
        return new SecP192K1Point(this, x, y);
    }

    protected ECPoint createRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
    {
        return new SecP192K1Point(this, x, y, zs);
    }

    public ECPoint getInfinity()
    {
        return infinity;
    }

    public ECLookupTable createCacheSafeLookupTable(ECPoint[] points, int off, final int len)
    {
        final int FE_INTS = 6;

        final int[] table = new int[len * FE_INTS * 2];
        {
            int pos = 0;
            for (int i = 0; i < len; ++i)
            {
                ECPoint p = points[off + i];
                Nat192.copy(((SecP192K1FieldElement)p.getRawXCoord()).x, 0, table, pos); pos += FE_INTS;
                Nat192.copy(((SecP192K1FieldElement)p.getRawYCoord()).x, 0, table, pos); pos += FE_INTS;
            }
        }

        return new AbstractECLookupTable()
        {
            public int getSize()
            {
                return len;
            }

            public ECPoint lookup(int index)
            {
                int[] x = Nat192.create(), y = Nat192.create();
                int pos = 0;

                for (int i = 0; i < len; ++i)
                {
                    int MASK = ((i ^ index) - 1) >> 31;

                    for (int j = 0; j < FE_INTS; ++j)
                    {
                        x[j] ^= table[pos + j] & MASK;
                        y[j] ^= table[pos + FE_INTS + j] & MASK;
                    }

                    pos += (FE_INTS * 2);
                }

                return createPoint(x, y);
            }

            public ECPoint lookupVar(int index)
            {
                int[] x = Nat192.create(), y = Nat192.create();
                int pos = index * FE_INTS * 2;

                for (int j = 0; j < FE_INTS; ++j)
                {
                    x[j] = table[pos + j];
                    y[j] = table[pos + FE_INTS + j];
                }

                return createPoint(x, y);
            }

            private ECPoint createPoint(int[] x, int[] y)
            {
                return createRawPoint(new SecP192K1FieldElement(x), new SecP192K1FieldElement(y), SECP192K1_AFFINE_ZS);
            }
        };
    }

    public ECFieldElement randomFieldElement(SecureRandom r)
    {
        int[] x = Nat192.create();
        SecP192K1Field.random(r, x);
        return new SecP192K1FieldElement(x);
    }

    public ECFieldElement randomFieldElementMult(SecureRandom r)
    {
        int[] x = Nat192.create();
        SecP192K1Field.randomMult(r, x);
        return new SecP192K1FieldElement(x);
    }
}