1 /*

     2  * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package java.security.spec;

    26 

    27 import java.math.BigInteger;

    28 

    29 /**

    30  * This immutable class specifies the set of domain parameters

    31  * used with elliptic curve cryptography (ECC).

    32  *

    33  * @see AlgorithmParameterSpec

    34  *

    35  * @author Valerie Peng

    36  *

    37  * @since 1.5

    38  */

    39 public class ECParameterSpec implements AlgorithmParameterSpec {

    40 

    41     private final EllipticCurve curve;

    42     private final ECPoint g;

    43     private final BigInteger n;

    44     private final int h;

    45 

    46     /**

    47      * Creates elliptic curve domain parameters based on the

    48      * specified values.

    49      * @param curve the elliptic curve which this parameter

    50      * defines.

    51      * @param g the generator which is also known as the base point.

    52      * @param n the order of the generator {@code g}.

    53      * @param h the cofactor.

    54      * @exception NullPointerException if {@code curve},

    55      * {@code g}, or {@code n} is null.

    56      * @exception IllegalArgumentException if {@code n}

    57      * or {@code h} is not positive.

    58      */

    59     public ECParameterSpec(EllipticCurve curve, ECPoint g,

    60                            BigInteger n, int h) {

    61         if (curve == null) {

    62             throw new NullPointerException("curve is null");

    63         }

    64         if (g == null) {

    65             throw new NullPointerException("g is null");

    66         }

    67         if (n == null) {

    68             throw new NullPointerException("n is null");

    69         }

    70         if (n.signum() != 1) {

    71             throw new IllegalArgumentException("n is not positive");

    72         }

    73         if (h <= 0) {

    74             throw new IllegalArgumentException("h is not positive");

    75         }

    76         this.curve = curve;

    77         this.g = g;

    78         this.n = n;

    79         this.h = h;

    80     }

    81 

    82     /**

    83      * Returns the elliptic curve that this parameter defines.

    84      * @return the elliptic curve that this parameter defines.

    85      */

    86     public EllipticCurve getCurve() {

    87         return curve;

    88     }

    89 

    90     /**

    91      * Returns the generator which is also known as the base point.

    92      * @return the generator which is also known as the base point.

    93      */

    94     public ECPoint getGenerator() {

    95         return g;

    96     }

    97 

    98     /**

    99      * Returns the order of the generator.

   100      * @return the order of the generator.

   101      */

   102     public BigInteger getOrder() {

   103         return n;

   104     }

   105 

   106     /**

   107      * Returns the cofactor.

   108      * @return the cofactor.

   109      */

   110     public int getCofactor() {

   111         return h;

   112     }

   113 }