J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2007 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 | } |