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| 1 | +/* | |
| 2 | + * Copyright (c) 1997, 2007, 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 com.sun.crypto.provider; | |
| 27 | + | |
| 28 | +import java.math.BigInteger; | |
| 29 | +import java.security.*; | |
| 30 | +import java.security.spec.*; | |
| 31 | +import javax.crypto.spec.DHParameterSpec; | |
| 32 | +import javax.crypto.spec.DHGenParameterSpec; | |
| 33 | + | |
| 34 | +/* | |
| 35 | + * This class generates parameters for the Diffie-Hellman algorithm. | |
| 36 | + * The parameters are a prime, a base, and optionally the length in bits of | |
| 37 | + * the private value. | |
| 38 | + * | |
| 39 | + * <p>The Diffie-Hellman parameter generation accepts the size in bits of the | |
| 40 | + * prime modulus and the size in bits of the random exponent as input. | |
| 41 | + * The size of the prime modulus defaults to 1024 bits. | |
| 42 | + * | |
| 43 | + * @author Jan Luehe | |
| 44 | + * | |
| 45 | + * | |
| 46 | + * @see java.security.AlgorithmParameters | |
| 47 | + * @see java.security.spec.AlgorithmParameterSpec | |
| 48 | + * @see DHParameters | |
| 49 | + */ | |
| 50 | +public final class DHParameterGenerator | |
| 51 | +extends AlgorithmParameterGeneratorSpi { | |
| 52 | + | |
| 53 | + // The size in bits of the prime modulus | |
| 54 | + private int primeSize = 1024; | |
| 55 | + | |
| 56 | + // The size in bits of the random exponent (private value) | |
| 57 | + private int exponentSize = 0; | |
| 58 | + | |
| 59 | + // The source of randomness | |
| 60 | + private SecureRandom random = null; | |
| 61 | + | |
| 62 | + /** | |
| 63 | + * Initializes this parameter generator for a certain keysize | |
| 64 | + * and source of randomness. | |
| 65 | + * The keysize is specified as the size in bits of the prime modulus. | |
| 66 | + * | |
| 67 | + * @param keysize the keysize (size of prime modulus) in bits | |
| 68 | + * @param random the source of randomness | |
| 69 | + */ | |
| 70 | + protected void engineInit(int keysize, SecureRandom random) { | |
| 71 | + if ((keysize < 512) || (keysize > 1024) || (keysize % 64 != 0)) { | |
| 72 | + throw new InvalidParameterException("Keysize must be multiple " | |
| 73 | + + "of 64, and can only range " | |
| 74 | + + "from 512 to 1024 " | |
| 75 | + + "(inclusive)"); | |
| 76 | + } | |
| 77 | + this.primeSize = keysize; | |
| 78 | + this.random = random; | |
| 79 | + } | |
| 80 | + | |
| 81 | + /** | |
| 82 | + * Initializes this parameter generator with a set of parameter | |
| 83 | + * generation values, which specify the size of the prime modulus and | |
| 84 | + * the size of the random exponent, both in bits. | |
| 85 | + * | |
| 86 | + * @param params the set of parameter generation values | |
| 87 | + * @param random the source of randomness | |
| 88 | + * | |
| 89 | + * @exception InvalidAlgorithmParameterException if the given parameter | |
| 90 | + * generation values are inappropriate for this parameter generator | |
| 91 | + */ | |
| 92 | + protected void engineInit(AlgorithmParameterSpec genParamSpec, | |
| 93 | + SecureRandom random) | |
| 94 | + throws InvalidAlgorithmParameterException { | |
| 95 | + if (!(genParamSpec instanceof DHGenParameterSpec)) { | |
| 96 | + throw new InvalidAlgorithmParameterException | |
| 97 | + ("Inappropriate parameter type"); | |
| 98 | + } | |
| 99 | + | |
| 100 | + DHGenParameterSpec dhParamSpec = (DHGenParameterSpec)genParamSpec; | |
| 101 | + | |
| 102 | + primeSize = dhParamSpec.getPrimeSize(); | |
| 103 | + if ((primeSize<512) || (primeSize>1024) || (primeSize%64 != 0)) { | |
| 104 | + throw new InvalidAlgorithmParameterException | |
| 105 | + ("Modulus size must be multiple of 64, and can only range " | |
| 106 | + + "from 512 to 1024 (inclusive)"); | |
| 107 | + } | |
| 108 | + | |
| 109 | + exponentSize = dhParamSpec.getExponentSize(); | |
| 110 | + if (exponentSize <= 0) { | |
| 111 | + throw new InvalidAlgorithmParameterException | |
| 112 | + ("Exponent size must be greater than zero"); | |
| 113 | + } | |
| 114 | + | |
| 115 | + // Require exponentSize < primeSize | |
| 116 | + if (exponentSize >= primeSize) { | |
| 117 | + throw new InvalidAlgorithmParameterException | |
| 118 | + ("Exponent size must be less than modulus size"); | |
| 119 | + } | |
| 120 | + } | |
| 121 | + | |
| 122 | + /** | |
| 123 | + * Generates the parameters. | |
| 124 | + * | |
| 125 | + * @return the new AlgorithmParameters object | |
| 126 | + */ | |
| 127 | + protected AlgorithmParameters engineGenerateParameters() { | |
| 128 | + AlgorithmParameters algParams = null; | |
| 129 | + | |
| 130 | + if (this.exponentSize == 0) { | |
| 131 | + this.exponentSize = this.primeSize - 1; | |
| 132 | + } | |
| 133 | + | |
| 134 | + if (this.random == null) | |
| 135 | + this.random = SunJCE.RANDOM; | |
| 136 | + | |
| 137 | + try { | |
| 138 | + AlgorithmParameterGenerator paramGen; | |
| 139 | + DSAParameterSpec dsaParamSpec; | |
| 140 | + | |
| 141 | + paramGen = AlgorithmParameterGenerator.getInstance("DSA"); | |
| 142 | + paramGen.init(this.primeSize, random); | |
| 143 | + algParams = paramGen.generateParameters(); | |
| 144 | + dsaParamSpec = (DSAParameterSpec) | |
| 145 | + algParams.getParameterSpec(DSAParameterSpec.class); | |
| 146 | + | |
| 147 | + DHParameterSpec dhParamSpec; | |
| 148 | + if (this.exponentSize > 0) { | |
| 149 | + dhParamSpec = new DHParameterSpec(dsaParamSpec.getP(), | |
| 150 | + dsaParamSpec.getG(), | |
| 151 | + this.exponentSize); | |
| 152 | + } else { | |
| 153 | + dhParamSpec = new DHParameterSpec(dsaParamSpec.getP(), | |
| 154 | + dsaParamSpec.getG()); | |
| 155 | + } | |
| 156 | + algParams = AlgorithmParameters.getInstance("DH", "SunJCE"); | |
| 157 | + algParams.init(dhParamSpec); | |
| 158 | + } catch (InvalidParameterSpecException e) { | |
| 159 | + // this should never happen | |
| 160 | + throw new RuntimeException(e.getMessage()); | |
| 161 | + } catch (NoSuchAlgorithmException e) { | |
| 162 | + // this should never happen, because we provide it | |
| 163 | + throw new RuntimeException(e.getMessage()); | |
| 164 | + } catch (NoSuchProviderException e) { | |
| 165 | + // this should never happen, because we provide it | |
| 166 | + throw new RuntimeException(e.getMessage()); | |
| 167 | + } | |
| 168 | + | |
| 169 | + return algParams; | |
| 170 | + } | |
| 171 | +} | |