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| 1 | /* | ||
| 2 | * Copyright (c) 2003, 2011, 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 | |||
| 26 | package java.security.spec; | ||
| 27 | |||
| 28 | import java.math.BigInteger; | ||
| 29 | import java.util.Arrays; | ||
| 30 | |||
| 31 | /** | ||
| 32 | * This immutable class holds the necessary values needed to represent | ||
| 33 | * an elliptic curve. | ||
| 34 | * | ||
| 35 | * @see ECField | ||
| 36 | * @see ECFieldFp | ||
| 37 | * @see ECFieldF2m | ||
| 38 | * | ||
| 39 | * @author Valerie Peng | ||
| 40 | * | ||
| 41 | * @since 1.5 | ||
| 42 | */ | ||
| 43 | public class EllipticCurve { | ||
| 44 | |||
| 45 | private final ECField field; | ||
| 46 | private final BigInteger a; | ||
| 47 | private final BigInteger b; | ||
| 48 | private final byte[] seed; | ||
| 49 | |||
| 50 | // Check coefficient c is a valid element in ECField field. | ||
| 51 | private static void checkValidity(ECField field, BigInteger c, | ||
| 52 | String cName) { | ||
| 53 | // can only perform check if field is ECFieldFp or ECFieldF2m. | ||
| 54 | if (field instanceof ECFieldFp) { | ||
| 55 | BigInteger p = ((ECFieldFp)field).getP(); | ||
| 56 | if (p.compareTo(c) != 1) { | ||
| 57 | throw new IllegalArgumentException(cName + " is too large"); | ||
| 58 | } else if (c.signum() < 0) { | ||
| 59 | throw new IllegalArgumentException(cName + " is negative"); | ||
| 60 | } | ||
| 61 | } else if (field instanceof ECFieldF2m) { | ||
| 62 | int m = ((ECFieldF2m)field).getM(); | ||
| 63 | if (c.bitLength() > m) { | ||
| 64 | throw new IllegalArgumentException(cName + " is too large"); | ||
| 65 | } | ||
| 66 | } | ||
| 67 | } | ||
| 68 | |||
| 69 | /** | ||
| 70 | * Creates an elliptic curve with the specified elliptic field | ||
| 71 | * <code>field</code> and the coefficients <code>a</code> and | ||
| 72 | * <code>b</code>. | ||
| 73 | * @param field the finite field that this elliptic curve is over. | ||
| 74 | * @param a the first coefficient of this elliptic curve. | ||
| 75 | * @param b the second coefficient of this elliptic curve. | ||
| 76 | * @exception NullPointerException if <code>field</code>, | ||
| 77 | * <code>a</code>, or <code>b</code> is null. | ||
| 78 | * @exception IllegalArgumentException if <code>a</code> | ||
| 79 | * or <code>b</code> is not null and not in <code>field</code>. | ||
| 80 | */ | ||
| 81 | public EllipticCurve(ECField field, BigInteger a, | ||
| 82 | BigInteger b) { | ||
| 83 | this(field, a, b, null); | ||
| 84 | } | ||
| 85 | |||
| 86 | /** | ||
| 87 | * Creates an elliptic curve with the specified elliptic field | ||
| 88 | * <code>field</code>, the coefficients <code>a</code> and | ||
| 89 | * <code>b</code>, and the <code>seed</code> used for curve generation. | ||
| 90 | * @param field the finite field that this elliptic curve is over. | ||
| 91 | * @param a the first coefficient of this elliptic curve. | ||
| 92 | * @param b the second coefficient of this elliptic curve. | ||
| 93 | * @param seed the bytes used during curve generation for later | ||
| 94 | * validation. Contents of this array are copied to protect against | ||
| 95 | * subsequent modification. | ||
| 96 | * @exception NullPointerException if <code>field</code>, | ||
| 97 | * <code>a</code>, or <code>b</code> is null. | ||
| 98 | * @exception IllegalArgumentException if <code>a</code> | ||
| 99 | * or <code>b</code> is not null and not in <code>field</code>. | ||
| 100 | */ | ||
| 101 | public EllipticCurve(ECField field, BigInteger a, | ||
| 102 | BigInteger b, byte[] seed) { | ||
| 103 | if (field == null) { | ||
| 104 | throw new NullPointerException("field is null"); | ||
| 105 | } | ||
| 106 | if (a == null) { | ||
| 107 | throw new NullPointerException("first coefficient is null"); | ||
| 108 | } | ||
| 109 | if (b == null) { | ||
| 110 | throw new NullPointerException("second coefficient is null"); | ||
| 111 | } | ||
| 112 | checkValidity(field, a, "first coefficient"); | ||
| 113 | checkValidity(field, b, "second coefficient"); | ||
| 114 | this.field = field; | ||
| 115 | this.a = a; | ||
| 116 | this.b = b; | ||
| 117 | if (seed != null) { | ||
| 118 | this.seed = seed.clone(); | ||
| 119 | } else { | ||
| 120 | this.seed = null; | ||
| 121 | } | ||
| 122 | } | ||
| 123 | |||
| 124 | /** | ||
| 125 | * Returns the finite field <code>field</code> that this | ||
| 126 | * elliptic curve is over. | ||
| 127 | * @return the field <code>field</code> that this curve | ||
| 128 | * is over. | ||
| 129 | */ | ||
| 130 | public ECField getField() { | ||
| 131 | return field; | ||
| 132 | } | ||
| 133 | |||
| 134 | /** | ||
| 135 | * Returns the first coefficient <code>a</code> of the | ||
| 136 | * elliptic curve. | ||
| 137 | * @return the first coefficient <code>a</code>. | ||
| 138 | */ | ||
| 139 | public BigInteger getA() { | ||
| 140 | return a; | ||
| 141 | } | ||
| 142 | |||
| 143 | /** | ||
| 144 | * Returns the second coefficient <code>b</code> of the | ||
| 145 | * elliptic curve. | ||
| 146 | * @return the second coefficient <code>b</code>. | ||
| 147 | */ | ||
| 148 | public BigInteger getB() { | ||
| 149 | return b; | ||
| 150 | } | ||
| 151 | |||
| 152 | /** | ||
| 153 | * Returns the seeding bytes <code>seed</code> used | ||
| 154 | * during curve generation. May be null if not specified. | ||
| 155 | * @return the seeding bytes <code>seed</code>. A new | ||
| 156 | * array is returned each time this method is called. | ||
| 157 | */ | ||
| 158 | public byte[] getSeed() { | ||
| 159 | if (seed == null) return null; | ||
| 160 | else return seed.clone(); | ||
| 161 | } | ||
| 162 | |||
| 163 | /** | ||
| 164 | * Compares this elliptic curve for equality with the | ||
| 165 | * specified object. | ||
| 166 | * @param obj the object to be compared. | ||
| 167 | * @return true if <code>obj</code> is an instance of | ||
| 168 | * EllipticCurve and the field, A, and B match, false otherwise. | ||
| 169 | */ | ||
| 170 | public boolean equals(Object obj) { | ||
| 171 | if (this == obj) return true; | ||
| 172 | if (obj instanceof EllipticCurve) { | ||
| 173 | EllipticCurve curve = (EllipticCurve) obj; | ||
| 174 | if ((field.equals(curve.field)) && | ||
| 175 | (a.equals(curve.a)) && | ||
| 176 | (b.equals(curve.b))) { | ||
| 177 | return true; | ||
| 178 | } | ||
| 179 | } | ||
| 180 | return false; | ||
| 181 | } | ||
| 182 | |||
| 183 | /** | ||
| 184 | * Returns a hash code value for this elliptic curve. | ||
| 185 | * @return a hash code value computed from the hash codes of the field, A, | ||
| 186 | * and B, as follows: | ||
| 187 | * <code> | ||
| 188 | * (field.hashCode() << 6) + (a.hashCode() << 4) + (b.hashCode() << 2) | ||
| 189 | * </code> | ||
| 190 | */ | ||
| 191 | public int hashCode() { | ||
| 192 | return (field.hashCode() << 6 + | ||
| 193 | (a.hashCode() << 4) + | ||
| 194 | (b.hashCode() << 2)); | ||
| 195 | } | ||
| 196 | } | ||