1 /*
   2  * Copyright (c) 2003, 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</code>.
  53      * @param h the cofactor.
  54      * @exception NullPointerException if <code>curve</code>,
  55      * <code>g</code>, or <code>n</code> is null.
  56      * @exception IllegalArgumentException if <code>n</code>
  57      * or <code>h</code> 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 }