jdk/src/share/classes/java/security/spec/ECParameterSpec.java

/*
 * Copyright 2003 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
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package java.security.spec;

import java.math.BigInteger;

/**
 * This immutable class specifies the set of domain parameters
 * used with elliptic curve cryptography (ECC).
 *
 * @see AlgorithmParameterSpec
 *
 * @author Valerie Peng
 *
 * @since 1.5
 */
public class ECParameterSpec implements AlgorithmParameterSpec {

    private final EllipticCurve curve;
    private final ECPoint g;
    private final BigInteger n;
    private final int h;

    /**
     * Creates elliptic curve domain parameters based on the
     * specified values.
     * @param curve the elliptic curve which this parameter
     * defines.
     * @param g the generator which is also known as the base point.
     * @param n the order of the generator <code>g</code>.
     * @param h the cofactor.
     * @exception NullPointerException if <code>curve</code>,
     * <code>g</code>, or <code>n</code> is null.
     * @exception IllegalArgumentException if <code>n</code>
     * or <code>h</code> is not positive.
     */
    public ECParameterSpec(EllipticCurve curve, ECPoint g,
                           BigInteger n, int h) {
        if (curve == null) {
            throw new NullPointerException("curve is null");
        }
        if (g == null) {
            throw new NullPointerException("g is null");
        }
        if (n == null) {
            throw new NullPointerException("n is null");
        }
        if (n.signum() != 1) {
            throw new IllegalArgumentException("n is not positive");
        }
        if (h <= 0) {
            throw new IllegalArgumentException("h is not positive");
        }
        this.curve = curve;
        this.g = g;
        this.n = n;
        this.h = h;
    }

    /**
     * Returns the elliptic curve that this parameter defines.
     * @return the elliptic curve that this parameter defines.
     */
    public EllipticCurve getCurve() {
        return curve;
    }

    /**
     * Returns the generator which is also known as the base point.
     * @return the generator which is also known as the base point.
     */
    public ECPoint getGenerator() {
        return g;
    }

    /**
     * Returns the order of the generator.
     * @return the order of the generator.
     */
    public BigInteger getOrder() {
        return n;
    }

    /**
     * Returns the cofactor.
     * @return the cofactor.
     */
    public int getCofactor() {
        return h;
    }
}