libjava/java/security/KeyPairGenerator.java

   1 /* KeyPairGenerator.java --- Key Pair Generator Class
   2    Copyright (C) 1999, 2002, 2003, 2004  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.security;
  40
  41 import gnu.java.security.Engine;
  42
  43 import java.security.spec.AlgorithmParameterSpec;
  44
  45 /**
  46  * <p>The <code>KeyPairGenerator</code> class is used to generate pairs of
  47  * public and private keys. Key pair generators are constructed using the
  48  * <code>getInstance()</code> factory methods (static methods that return
  49  * instances of a given class).</p>
  50  *
  51  * <p>A Key pair generator for a particular algorithm creates a public/private
  52  * key pair that can be used with this algorithm. It also associates
  53  * algorithm-specific parameters with each of the generated keys.</p>
  54  *
  55  * <p>There are two ways to generate a key pair: in an algorithm-independent
  56  * manner, and in an algorithm-specific manner. The only difference between the
  57  * two is the initialization of the object:</p>
  58  *
  59  * <ul>
  60  * <li><b>Algorithm-Independent Initialization</b><br/>
  61  *     All key pair generators share the concepts of a <i>keysize</i> and a
  62  *     <i>source of randomness</i>. The <i>keysize</i> is interpreted differently
  63  *     for different algorithms (e.g., in the case of the <i>DSA</i> algorithm,
  64  *     the <i>keysize</i> corresponds to the length of the modulus). There is an
  65  *     <code>initialize()</code> method in this <code>KeyPairGenerator</code>
  66  *     class that takes these two universally shared types of arguments. There
  67  *     is also one that takes just a <i>keysize</i> argument, and uses the
  68  *     {@link SecureRandom} implementation of the highest-priority installed
  69  *     provider as the <i>source of randomness</i>. (If none of the installed
  70  *     providers supply an implementation of {@link SecureRandom}, a
  71  *     system-provided source of randomness is used.)
  72  *
  73  *     <p>Since no other parameters are specified when you call the above
  74  *     algorithm-independent initialize methods, it is up to the provider what
  75  *     to do about the algorithm-specific parameters (if any) to be associated
  76  *     with each of the keys.</p>
  77  *
  78  *     <p>If the algorithm is the <i>DSA</i> algorithm, and the <i>keysize</i>
  79  *     (modulus size) is <code>512</code>, <code>768</code>, or <code>1024</code>,
  80  *     then the <b>GNU</b> provider uses a set of precomputed values for the
  81  *     <code>p</code>, <code>q</code>, and <code>g</code> parameters. If the
  82  *     <i>modulus size</i> is not one of the above values, the <b>GNU</b>
  83  *     provider creates a new set of parameters. Other providers might have
  84  *     precomputed parameter sets for more than just the three modulus sizes
  85  *     mentioned above. Still others might not have a list of precomputed
  86  *     parameters at all and instead always create new parameter sets.</p></li>
  87  * <li><b>Algorithm-Specific Initialization</b><br/>
  88  *     For situations where a set of algorithm-specific parameters already
  89  *     exists (e.g., so-called <i>community parameters</i> in <i>DSA</i>), there
  90  *     are two initialize methods that have an {@link AlgorithmParameterSpec}
  91  *     argument. One also has a {@link SecureRandom} argument, while the the
  92  *     other uses the {@link SecureRandom} implementation of the highest-priority
  93  *     installed provider as the source of randomness. (If none of the installed
  94  *     providers supply an implementation of {@link SecureRandom}, a
  95  *     system-provided source of randomness is used.)</li>
  96  * </ul>
  97  *
  98  * <p>In case the client does not explicitly initialize the
  99  * <code>KeyPairGenerator</code> (via a call to an initialize method), each
 100  * provider must supply (and document) a default initialization. For example,
 101  * the <b>GNU</b> provider uses a default modulus size (keysize) of
 102  * <code>1024</code> bits.</p>
 103  *
 104  * <p>Note that this class is abstract and extends from {@link
 105  * KeyPairGeneratorSpi} for historical reasons. Application developers should
 106  * only take notice of the methods defined in this <code>KeyPairGenerator</code>
 107  * class; all the methods in the superclass are intended for cryptographic
 108  * service providers who wish to supply their own implementations of key pair
 109  * generators.</p>
 110  *
 111  * @see Signature
 112  * @see KeyPair
 113  * @see AlgorithmParameterSpec
 114  * @author Mark Benvenuto
 115  * @author Casey Marshall
 116  */
 117 public abstract class KeyPairGenerator extends KeyPairGeneratorSpi
 118 {
 119   /** The service name for key pair generators. */
 120   private static final String KEY_PAIR_GENERATOR = "KeyPairGenerator";
 121
 122   Provider provider;
 123   private String algorithm;
 124
 125   /**
 126    * Creates a <code>KeyPairGenerator</code> object for the specified
 127    * algorithm.
 128    *
 129    * @param algorithm the standard string name of the algorithm.
 130    * See Appendix A in the Java Cryptography Architecture API
 131    * Specification &amp; Reference for information about standard
 132    * algorithm names.
 133    */
 134   protected KeyPairGenerator(String algorithm)
 135   {
 136     this.algorithm = algorithm;
 137     this.provider = null;
 138   }
 139
 140   /**
 141    * Returns the standard name of the algorithm for this key pair generator.
 142    * See Appendix A in the Java Cryptography Architecture API Specification
 143    * &amp; Reference for information about standard algorithm names.
 144    *
 145    * @return the standard string name of the algorithm.
 146    */
 147   public String getAlgorithm()
 148   {
 149     return algorithm;
 150   }
 151
 152   /**
 153    * Generates a <code>KeyPairGenerator</code> object that implements the
 154    * specified digest algorithm. If the default provider package provides an
 155    * implementation of the requested digest algorithm, an instance of
 156    * <code>KeyPairGenerator</code> containing that implementation is returned.
 157    * If the algorithm is not available in the default package, other packages
 158    * are searched.
 159    *
 160    * @param algorithm the standard string name of the algorithm. See Appendix A
 161    * in the Java Cryptography Architecture API Specification &amp; Reference for
 162    * information about standard algorithm names.
 163    * @return the new <code>KeyPairGenerator</code> object.
 164    * @throws NoSuchAlgorithmException if the algorithm is not available in the
 165    * environment.
 166    */
 167   public static KeyPairGenerator getInstance(String algorithm)
 168     throws NoSuchAlgorithmException
 169   {
 170     Provider[] p = Security.getProviders();
 171     for (int i = 0; i < p.length; i++)
 172       {
 173         try
 174           {
 175             return getInstance(algorithm, p[i]);
 176           }
 177         catch (NoSuchAlgorithmException e)
 178           {
 179             // Ignored.
 180           }
 181       }
 182
 183     throw new NoSuchAlgorithmException(algorithm);
 184   }
 185
 186   /**
 187    * Generates a <code>KeyPairGenerator</code> object implementing the
 188    * specified algorithm, as supplied from the specified provider, if
 189    * such an algorithm is available from the provider.
 190    *
 191    * @param algorithm the standard string name of the algorithm. See
 192    * Appendix A in the Java Cryptography Architecture API Specification
 193    * &amp; Reference for information about standard algorithm names.
 194    * @param provider the string name of the provider.
 195    * @return the new <code>KeyPairGenerator</code> object.
 196    * @throws NoSuchAlgorithmException if the algorithm is not available
 197    * from the provider.
 198    * @throws NoSuchProviderException if the provider is not available in the
 199    * environment.
 200    * @throws IllegalArgumentException if the provider name is <code>null</code>
 201    * or empty.
 202    * @see Provider
 203    */
 204   public static KeyPairGenerator getInstance(String algorithm, String provider)
 205     throws NoSuchAlgorithmException, NoSuchProviderException
 206   {
 207     Provider p = Security.getProvider(provider);
 208     if (p == null)
 209       throw new NoSuchProviderException(provider);
 210
 211     return getInstance(algorithm, p);
 212   }
 213
 214   /**
 215    * Generates a <code>KeyPairGenerator</code> object implementing the specified
 216    * algorithm, as supplied from the specified provider, if such an algorithm is
 217    * available from the provider. Note: the provider doesn't have to be
 218    * registered.
 219    *
 220    * @param algorithm the standard string name of the algorithm. See Appendix A
 221    * in the Java Cryptography Architecture API Specification &amp; Reference for
 222    * information about standard algorithm names.
 223    * @param provider the provider.
 224    * @return the new <code>KeyPairGenerator</code> object.
 225    * @throws NoSuchAlgorithmException if the <code>algorithm</code> is not
 226    * available from the <code>provider</code>.
 227    * @throws IllegalArgumentException if the <code>provider</code> is
 228    * <code>null</code>.
 229    * @since 1.4
 230    * @see Provider
 231    */
 232   public static KeyPairGenerator getInstance(String algorithm,
 233                                              Provider provider)
 234     throws NoSuchAlgorithmException
 235   {
 236     if (provider == null)
 237       throw new IllegalArgumentException("Illegal provider");
 238
 239     Object o = null;
 240     try
 241       {
 242         o = Engine.getInstance(KEY_PAIR_GENERATOR, algorithm, provider);
 243       }
 244     catch (java.lang.reflect.InvocationTargetException ite)
 245       {
 246         throw new NoSuchAlgorithmException(algorithm);
 247       }
 248
 249     KeyPairGenerator result = null;
 250     if (o instanceof KeyPairGeneratorSpi)
 251       {
 252         result = new DummyKeyPairGenerator((KeyPairGeneratorSpi) o, algorithm);
 253       }
 254     else if (o instanceof KeyPairGenerator)
 255       {
 256         result = (KeyPairGenerator) o;
 257         result.algorithm = algorithm;
 258       }
 259     result.provider = provider;
 260     return result;
 261   }
 262
 263   /**
 264    * Returns the provider of this key pair generator object.
 265    *
 266    * @return the provider of this key pair generator object.
 267    */
 268   public final Provider getProvider()
 269   {
 270     return provider;
 271   }
 272
 273   /**
 274    * Initializes the key pair generator for a certain keysize using a default
 275    * parameter set and the {@link SecureRandom} implementation of the
 276    * highest-priority installed provider as the source of randomness. (If none
 277    * of the installed providers supply an implementation of {@link SecureRandom},
 278    * a system-provided source of randomness is used.)
 279    *
 280    * @param keysize the keysize. This is an algorithm-specific metric, such as
 281    * modulus length, specified in number of bits.
 282    * @throws InvalidParameterException if the keysize is not supported by this
 283    * <code>KeyPairGenerator</code> object.
 284    */
 285   public void initialize(int keysize)
 286   {
 287     initialize(keysize, new SecureRandom());
 288   }
 289
 290   /**
 291    * Initializes the key pair generator for a certain keysize with the given
 292    * source of randomness (and a default parameter set).
 293    *
 294    * @param keysize the keysize. This is an algorithm-specific metric, such as
 295    * modulus length, specified in number of bits.
 296    * @param random the source of randomness.
 297    * @throws InvalidParameterException if the <code>keysize</code> is not
 298    * supported by this <code>KeyPairGenerator</code> object.
 299    * @since 1.2
 300    */
 301   public void initialize(int keysize, SecureRandom random)
 302   {
 303     initialize(keysize, random);
 304   }
 305
 306   /**
 307    * <p>Initializes the key pair generator using the specified parameter set and
 308    * the {@link SecureRandom} implementation of the highest-priority installed
 309    * provider as the source of randomness. (If none of the installed providers
 310    * supply an implementation of {@link SecureRandom}, a system-provided source
 311    * of randomness is used.)</p>
 312    *
 313    * <p>This concrete method has been added to this previously-defined abstract
 314    * class. This method calls the
 315    * {@link KeyPairGeneratorSpi#initialize(AlgorithmParameterSpec, SecureRandom)}
 316    * initialize method, passing it <code>params</code> and a source of
 317    * randomness (obtained from the highest-priority installed provider or
 318    * system-provided if none of the installed providers supply one). That
 319    * initialize method always throws an {@link UnsupportedOperationException}
 320    * if it is not overridden by the provider.</p>
 321    *
 322    * @param params the parameter set used to generate the keys.
 323    * @throws InvalidAlgorithmParameterException if the given parameters are
 324    * inappropriate for this key pair generator.
 325    * @since 1.2
 326    */
 327   public void initialize(AlgorithmParameterSpec params)
 328     throws InvalidAlgorithmParameterException
 329   {
 330     initialize(params, new SecureRandom());
 331   }
 332
 333   /**
 334    * <p>Initializes the key pair generator with the given parameter set and
 335    * source of randomness.</p>
 336    *
 337    * <p>This concrete method has been added to this previously-defined abstract
 338    * class. This method calls the
 339    * {@link KeyPairGeneratorSpi#initialize(AlgorithmParameterSpec, SecureRandom)}
 340    * initialize method, passing it <code>params</code> and <code>random</code>.
 341    * That initialize method always throws an {@link UnsupportedOperationException}
 342    * if it is not overridden by the provider.</p>
 343    *
 344    * @param params the parameter set used to generate the keys.
 345    * @param random the source of randomness.
 346    * @throws InvalidAlgorithmParameterException if the given parameters are
 347    * inappropriate for this key pair generator.
 348    * @since 1.2
 349    */
 350   public void initialize(AlgorithmParameterSpec params, SecureRandom random)
 351     throws InvalidAlgorithmParameterException
 352   {
 353     super.initialize(params, random);
 354   }
 355
 356   /**
 357    * <p>Generates a key pair.</p>
 358    *
 359    * <p>If this <code>KeyPairGenerator</code> has not been initialized
 360    * explicitly, provider-specific defaults will be used for the size and other
 361    * (algorithm-specific) values of the generated keys.</p>
 362    *
 363    * <p>This will generate a new key pair every time it is called.</p>
 364    *
 365    * <p>This method is functionally equivalent to {@link #generateKeyPair()}.</p>
 366    *
 367    * @return the generated key pair.
 368    * @since 1.2
 369    */
 370   public final KeyPair genKeyPair()
 371   {
 372     try
 373       {
 374         return getInstance("DSA", "GNU").generateKeyPair();
 375       }
 376     catch (Exception e)
 377       {
 378         System.err.println("genKeyPair failed: " + e);
 379         e.printStackTrace();
 380         return null;
 381       }
 382   }
 383
 384   /**
 385    * <p>Generates a key pair.</p>
 386    *
 387    * <p>If this <code>KeyPairGenerator</code> has not been initialized
 388    * explicitly, provider-specific defaults will be used for the size and other
 389    * (algorithm-specific) values of the generated keys.</p>
 390    *
 391    * <p>This will generate a new key pair every time it is called.</p>
 392    *
 393    * <p>This method is functionally equivalent to {@link #genKeyPair()}.</p>
 394    *
 395    * @return the generated key pair.
 396    */
 397   public KeyPair generateKeyPair()
 398   {
 399     return genKeyPair();
 400   }
 401 }