J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2006 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 java.security; |
| 27 | |
| 28 | import java.security.spec.AlgorithmParameterSpec; |
| 29 | |
| 30 | /** |
| 31 | * The <code>AlgorithmParameterGenerator</code> class is used to generate a |
| 32 | * set of |
| 33 | * parameters to be used with a certain algorithm. Parameter generators |
| 34 | * are constructed using the <code>getInstance</code> factory methods |
| 35 | * (static methods that return instances of a given class). |
| 36 | * |
| 37 | * <P>The object that will generate the parameters can be initialized |
| 38 | * in two different ways: in an algorithm-independent manner, or in an |
| 39 | * algorithm-specific manner: |
| 40 | * |
| 41 | * <ul> |
| 42 | * <li>The algorithm-independent approach uses the fact that all parameter |
| 43 | * generators share the concept of a "size" and a |
| 44 | * source of randomness. The measure of size is universally shared |
| 45 | * by all algorithm parameters, though it is interpreted differently |
| 46 | * for different algorithms. For example, in the case of parameters for |
| 47 | * the <i>DSA</i> algorithm, "size" corresponds to the size |
| 48 | * of the prime modulus (in bits). |
| 49 | * When using this approach, algorithm-specific parameter generation |
| 50 | * values - if any - default to some standard values, unless they can be |
| 51 | * derived from the specified size.<P> |
| 52 | * |
| 53 | * <li>The other approach initializes a parameter generator object |
| 54 | * using algorithm-specific semantics, which are represented by a set of |
| 55 | * algorithm-specific parameter generation values. To generate |
| 56 | * Diffie-Hellman system parameters, for example, the parameter generation |
| 57 | * values usually |
| 58 | * consist of the size of the prime modulus and the size of the |
| 59 | * random exponent, both specified in number of bits. |
| 60 | * </ul> |
| 61 | * |
| 62 | * <P>In case the client does not explicitly initialize the |
| 63 | * AlgorithmParameterGenerator |
| 64 | * (via a call to an <code>init</code> method), each provider must supply (and |
| 65 | * document) a default initialization. For example, the Sun provider uses a |
| 66 | * default modulus prime size of 1024 bits for the generation of DSA |
| 67 | * parameters. |
| 68 | * |
| 69 | * @author Jan Luehe |
| 70 | * |
| 71 | * |
| 72 | * @see AlgorithmParameters |
| 73 | * @see java.security.spec.AlgorithmParameterSpec |
| 74 | * |
| 75 | * @since 1.2 |
| 76 | */ |
| 77 | |
| 78 | public class AlgorithmParameterGenerator { |
| 79 | |
| 80 | // The provider |
| 81 | private Provider provider; |
| 82 | |
| 83 | // The provider implementation (delegate) |
| 84 | private AlgorithmParameterGeneratorSpi paramGenSpi; |
| 85 | |
| 86 | // The algorithm |
| 87 | private String algorithm; |
| 88 | |
| 89 | /** |
| 90 | * Creates an AlgorithmParameterGenerator object. |
| 91 | * |
| 92 | * @param paramGenSpi the delegate |
| 93 | * @param provider the provider |
| 94 | * @param algorithm the algorithm |
| 95 | */ |
| 96 | protected AlgorithmParameterGenerator |
| 97 | (AlgorithmParameterGeneratorSpi paramGenSpi, Provider provider, |
| 98 | String algorithm) { |
| 99 | this.paramGenSpi = paramGenSpi; |
| 100 | this.provider = provider; |
| 101 | this.algorithm = algorithm; |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * Returns the standard name of the algorithm this parameter |
| 106 | * generator is associated with. |
| 107 | * |
| 108 | * @return the string name of the algorithm. |
| 109 | */ |
| 110 | public final String getAlgorithm() { |
| 111 | return this.algorithm; |
| 112 | } |
| 113 | |
| 114 | /** |
| 115 | * Returns an AlgorithmParameterGenerator object for generating |
| 116 | * a set of parameters to be used with the specified algorithm. |
| 117 | * |
| 118 | * <p> This method traverses the list of registered security Providers, |
| 119 | * starting with the most preferred Provider. |
| 120 | * A new AlgorithmParameterGenerator object encapsulating the |
| 121 | * AlgorithmParameterGeneratorSpi implementation from the first |
| 122 | * Provider that supports the specified algorithm is returned. |
| 123 | * |
| 124 | * <p> Note that the list of registered providers may be retrieved via |
| 125 | * the {@link Security#getProviders() Security.getProviders()} method. |
| 126 | * |
| 127 | * @param algorithm the name of the algorithm this |
| 128 | * parameter generator is associated with. |
| 129 | * See Appendix A in the <a href= |
| 130 | * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA"> |
| 131 | * Java Cryptography Architecture API Specification & Reference </a> |
| 132 | * for information about standard algorithm names. |
| 133 | * |
| 134 | * @return the new AlgorithmParameterGenerator object. |
| 135 | * |
| 136 | * @exception NoSuchAlgorithmException if no Provider supports an |
| 137 | * AlgorithmParameterGeneratorSpi implementation for the |
| 138 | * specified algorithm. |
| 139 | * |
| 140 | * @see Provider |
| 141 | */ |
| 142 | public static AlgorithmParameterGenerator getInstance(String algorithm) |
| 143 | throws NoSuchAlgorithmException { |
| 144 | try { |
| 145 | Object[] objs = Security.getImpl(algorithm, |
| 146 | "AlgorithmParameterGenerator", |
| 147 | (String)null); |
| 148 | return new AlgorithmParameterGenerator |
| 149 | ((AlgorithmParameterGeneratorSpi)objs[0], |
| 150 | (Provider)objs[1], |
| 151 | algorithm); |
| 152 | } catch(NoSuchProviderException e) { |
| 153 | throw new NoSuchAlgorithmException(algorithm + " not found"); |
| 154 | } |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Returns an AlgorithmParameterGenerator object for generating |
| 159 | * a set of parameters to be used with the specified algorithm. |
| 160 | * |
| 161 | * <p> A new AlgorithmParameterGenerator object encapsulating the |
| 162 | * AlgorithmParameterGeneratorSpi implementation from the specified provider |
| 163 | * is returned. The specified provider must be registered |
| 164 | * in the security provider list. |
| 165 | * |
| 166 | * <p> Note that the list of registered providers may be retrieved via |
| 167 | * the {@link Security#getProviders() Security.getProviders()} method. |
| 168 | * |
| 169 | * @param algorithm the name of the algorithm this |
| 170 | * parameter generator is associated with. |
| 171 | * See Appendix A in the <a href= |
| 172 | * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA"> |
| 173 | * Java Cryptography Architecture API Specification & Reference </a> |
| 174 | * for information about standard algorithm names. |
| 175 | * |
| 176 | * @param provider the string name of the Provider. |
| 177 | * |
| 178 | * @return the new AlgorithmParameterGenerator object. |
| 179 | * |
| 180 | * @exception NoSuchAlgorithmException if an AlgorithmParameterGeneratorSpi |
| 181 | * implementation for the specified algorithm is not |
| 182 | * available from the specified provider. |
| 183 | * |
| 184 | * @exception NoSuchProviderException if the specified provider is not |
| 185 | * registered in the security provider list. |
| 186 | * |
| 187 | * @exception IllegalArgumentException if the provider name is null |
| 188 | * or empty. |
| 189 | * |
| 190 | * @see Provider |
| 191 | */ |
| 192 | public static AlgorithmParameterGenerator getInstance(String algorithm, |
| 193 | String provider) |
| 194 | throws NoSuchAlgorithmException, NoSuchProviderException |
| 195 | { |
| 196 | if (provider == null || provider.length() == 0) |
| 197 | throw new IllegalArgumentException("missing provider"); |
| 198 | Object[] objs = Security.getImpl(algorithm, |
| 199 | "AlgorithmParameterGenerator", |
| 200 | provider); |
| 201 | return new AlgorithmParameterGenerator |
| 202 | ((AlgorithmParameterGeneratorSpi)objs[0], (Provider)objs[1], |
| 203 | algorithm); |
| 204 | } |
| 205 | |
| 206 | /** |
| 207 | * Returns an AlgorithmParameterGenerator object for generating |
| 208 | * a set of parameters to be used with the specified algorithm. |
| 209 | * |
| 210 | * <p> A new AlgorithmParameterGenerator object encapsulating the |
| 211 | * AlgorithmParameterGeneratorSpi implementation from the specified Provider |
| 212 | * object is returned. Note that the specified Provider object |
| 213 | * does not have to be registered in the provider list. |
| 214 | * |
| 215 | * @param algorithm the string name of the algorithm this |
| 216 | * parameter generator is associated with. |
| 217 | * See Appendix A in the <a href= |
| 218 | * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA"> |
| 219 | * Java Cryptography Architecture API Specification & Reference </a> |
| 220 | * for information about standard algorithm names. |
| 221 | * |
| 222 | * @param provider the Provider object. |
| 223 | * |
| 224 | * @return the new AlgorithmParameterGenerator object. |
| 225 | * |
| 226 | * @exception NoSuchAlgorithmException if an AlgorithmParameterGeneratorSpi |
| 227 | * implementation for the specified algorithm is not available |
| 228 | * from the specified Provider object. |
| 229 | * |
| 230 | * @exception IllegalArgumentException if the specified provider is null. |
| 231 | * |
| 232 | * @see Provider |
| 233 | * |
| 234 | * @since 1.4 |
| 235 | */ |
| 236 | public static AlgorithmParameterGenerator getInstance(String algorithm, |
| 237 | Provider provider) |
| 238 | throws NoSuchAlgorithmException |
| 239 | { |
| 240 | if (provider == null) |
| 241 | throw new IllegalArgumentException("missing provider"); |
| 242 | Object[] objs = Security.getImpl(algorithm, |
| 243 | "AlgorithmParameterGenerator", |
| 244 | provider); |
| 245 | return new AlgorithmParameterGenerator |
| 246 | ((AlgorithmParameterGeneratorSpi)objs[0], (Provider)objs[1], |
| 247 | algorithm); |
| 248 | } |
| 249 | |
| 250 | /** |
| 251 | * Returns the provider of this algorithm parameter generator object. |
| 252 | * |
| 253 | * @return the provider of this algorithm parameter generator object |
| 254 | */ |
| 255 | public final Provider getProvider() { |
| 256 | return this.provider; |
| 257 | } |
| 258 | |
| 259 | /** |
| 260 | * Initializes this parameter generator for a certain size. |
| 261 | * To create the parameters, the <code>SecureRandom</code> |
| 262 | * implementation of the highest-priority installed provider is used as |
| 263 | * the source of randomness. |
| 264 | * (If none of the installed providers supply an implementation of |
| 265 | * <code>SecureRandom</code>, a system-provided source of randomness is |
| 266 | * used.) |
| 267 | * |
| 268 | * @param size the size (number of bits). |
| 269 | */ |
| 270 | public final void init(int size) { |
| 271 | paramGenSpi.engineInit(size, new SecureRandom()); |
| 272 | } |
| 273 | |
| 274 | /** |
| 275 | * Initializes this parameter generator for a certain size and source |
| 276 | * of randomness. |
| 277 | * |
| 278 | * @param size the size (number of bits). |
| 279 | * @param random the source of randomness. |
| 280 | */ |
| 281 | public final void init(int size, SecureRandom random) { |
| 282 | paramGenSpi.engineInit(size, random); |
| 283 | } |
| 284 | |
| 285 | /** |
| 286 | * Initializes this parameter generator with a set of algorithm-specific |
| 287 | * parameter generation values. |
| 288 | * To generate the parameters, the <code>SecureRandom</code> |
| 289 | * implementation of the highest-priority installed provider is used as |
| 290 | * the source of randomness. |
| 291 | * (If none of the installed providers supply an implementation of |
| 292 | * <code>SecureRandom</code>, a system-provided source of randomness is |
| 293 | * used.) |
| 294 | * |
| 295 | * @param genParamSpec the set of algorithm-specific parameter generation values. |
| 296 | * |
| 297 | * @exception InvalidAlgorithmParameterException if the given parameter |
| 298 | * generation values are inappropriate for this parameter generator. |
| 299 | */ |
| 300 | public final void init(AlgorithmParameterSpec genParamSpec) |
| 301 | throws InvalidAlgorithmParameterException { |
| 302 | paramGenSpi.engineInit(genParamSpec, new SecureRandom()); |
| 303 | } |
| 304 | |
| 305 | /** |
| 306 | * Initializes this parameter generator with a set of algorithm-specific |
| 307 | * parameter generation values. |
| 308 | * |
| 309 | * @param genParamSpec the set of algorithm-specific parameter generation values. |
| 310 | * @param random the source of randomness. |
| 311 | * |
| 312 | * @exception InvalidAlgorithmParameterException if the given parameter |
| 313 | * generation values are inappropriate for this parameter generator. |
| 314 | */ |
| 315 | public final void init(AlgorithmParameterSpec genParamSpec, |
| 316 | SecureRandom random) |
| 317 | throws InvalidAlgorithmParameterException { |
| 318 | paramGenSpi.engineInit(genParamSpec, random); |
| 319 | } |
| 320 | |
| 321 | /** |
| 322 | * Generates the parameters. |
| 323 | * |
| 324 | * @return the new AlgorithmParameters object. |
| 325 | */ |
| 326 | public final AlgorithmParameters generateParameters() { |
| 327 | return paramGenSpi.engineGenerateParameters(); |
| 328 | } |
| 329 | } |