001 /*
002 * Copyright 2003 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025 package java.security.spec;
026
027 import java.math.BigInteger;
028
029 /**
030 * This immutable class specifies the set of domain parameters
031 * used with elliptic curve cryptography (ECC).
032 *
033 * @see AlgorithmParameterSpec
034 *
035 * @author Valerie Peng
036 * @version 1.10, 05/05/07
037 *
038 * @since 1.5
039 */
040 public class ECParameterSpec implements AlgorithmParameterSpec {
041
042 private final EllipticCurve curve;
043 private final ECPoint g;
044 private final BigInteger n;
045 private final int h;
046
047 /**
048 * Creates elliptic curve domain parameters based on the
049 * specified values.
050 * @param curve the elliptic curve which this parameter
051 * defines.
052 * @param g the generator which is also known as the base point.
053 * @param n the order of the generator <code>g</code>.
054 * @param h the cofactor.
055 * @exception NullPointerException if <code>curve</code>,
056 * <code>g</code>, or <code>n</code> is null.
057 * @exception IllegalArgumentException if <code>n</code>
058 * or <code>h</code> is not positive.
059 */
060 public ECParameterSpec(EllipticCurve curve, ECPoint g,
061 BigInteger n, int h) {
062 if (curve == null) {
063 throw new NullPointerException("curve is null");
064 }
065 if (g == null) {
066 throw new NullPointerException("g is null");
067 }
068 if (n == null) {
069 throw new NullPointerException("n is null");
070 }
071 if (n.signum() != 1) {
072 throw new IllegalArgumentException("n is not positive");
073 }
074 if (h <= 0) {
075 throw new IllegalArgumentException("h is not positive");
076 }
077 this .curve = curve;
078 this .g = g;
079 this .n = n;
080 this .h = h;
081 }
082
083 /**
084 * Returns the elliptic curve that this parameter defines.
085 * @return the elliptic curve that this parameter defines.
086 */
087 public EllipticCurve getCurve() {
088 return curve;
089 }
090
091 /**
092 * Returns the generator which is also known as the base point.
093 * @return the generator which is also known as the base point.
094 */
095 public ECPoint getGenerator() {
096 return g;
097 }
098
099 /**
100 * Returns the order of the generator.
101 * @return the order of the generator.
102 */
103 public BigInteger getOrder() {
104 return n;
105 }
106
107 /**
108 * Returns the cofactor.
109 * @return the cofactor.
110 */
111 public int getCofactor() {
112 return h;
113 }
114 }
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