source: trunk/src/gcc/libjava/java/security/KeyPairGenerator.java@ 1392

/* KeyPairGenerator.java --- Key Pair Generator Class
   Copyright (C) 1999, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

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General Public License for more details.

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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
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exception statement from your version. */

package java.security;

import java.security.spec.AlgorithmParameterSpec;

/**
   KeyPairGenerator is the class used to generate key pairs
   for a security algorithm.

   The KeyPairGenerator is created with the getInstance()
   methods. The class is used to generate public and private
   keys for an algorithm and associate it with 
   algorithm parameters.

   @author Mark Benvenuto
 */
public abstract class KeyPairGenerator extends KeyPairGeneratorSpi
{
  Provider provider;
  private String algorithm;

  /**
     Constructs a new KeyPairGenerator

     @param algorithm the algorithm to use
   */
  protected KeyPairGenerator(String algorithm)
  {
    this.algorithm = algorithm;
    this.provider = null;
  }

  /**
     Returns the name of the algorithm used

     @return A string with the name of the algorithm
   */
  public String getAlgorithm()
  {
    return algorithm;
  }

  /** 
     Gets an instance of the KeyPairGenerator class 
     which generates key pairs for the specified algorithm. 
     If the algorithm is not found then, it throws NoSuchAlgorithmException.

     @param algorithm the name of algorithm to choose
     @return a AlgorithmParameterGenerator repesenting the desired algorithm

     @throws NoSuchAlgorithmException if the algorithm is not implemented by
                                      providers
   */
  public static KeyPairGenerator getInstance(String algorithm) throws
    NoSuchAlgorithmException
  {
    Provider[] p = Security.getProviders();

    for (int i = 0; i < p.length; i++)
      {
        try
          {
            return getInstance(algorithm, p[i]);
          }
        catch (NoSuchAlgorithmException ignored) {}
      }

    throw new NoSuchAlgorithmException(algorithm);
  }

  /** 
     Gets an instance of the KeyPairGenerator class 
     which generates key pairs for the specified algorithm. 
     If the algorithm is not found then, it throws NoSuchAlgorithmException.

     @param algorithm the name of algorithm to choose
     @param provider the name of the provider to find the algorithm in
     @return a AlgorithmParameterGenerator repesenting the desired algorithm

     @throws NoSuchAlgorithmException if the algorithm is not implemented by
                                      the provider
     @throws NoSuchProviderException if the provider is not found
   */
  public static KeyPairGenerator getInstance(String algorithm, String provider)
    throws NoSuchAlgorithmException, NoSuchProviderException
  {
    Provider p = Security.getProvider(provider);
    if (p == null)
      throw new NoSuchProviderException(provider);

    return getInstance(algorithm, p);
  }

  private static KeyPairGenerator getInstance(String algorithm, Provider p)
    throws NoSuchAlgorithmException
  {
    // try the name as is
    String className = p.getProperty("KeyPairGenerator." + algorithm);
    if (className == null) { // try all uppercase
      String upper = algorithm.toUpperCase();
      className = p.getProperty("KeyPairGenerator." + upper);
      if (className == null) { // try if it's an alias
        String alias = p.getProperty("Alg.Alias.KeyPairGenerator." + algorithm);
        if (alias == null) { // try all-uppercase alias name
          alias = p.getProperty("Alg.Alias.KeyPairGenerator." + upper);
          if (alias == null) { // spit the dummy
            throw new NoSuchAlgorithmException(algorithm);
          }
        }
        className = p.getProperty("KeyPairGenerator." + alias);
        if (className == null) {
          throw new NoSuchAlgorithmException(algorithm);
        }
      }
    }
    return getInstance(className, algorithm, p);
  }

  private static KeyPairGenerator getInstance(String classname,
                                              String algorithm,
                                              Provider provider)
    throws NoSuchAlgorithmException
  {
    try
      {
        Object o = Class.forName(classname).newInstance();
        KeyPairGenerator kpg;
        if (o instanceof KeyPairGeneratorSpi)
          kpg = new DummyKeyPairGenerator((KeyPairGeneratorSpi) o, algorithm);
        else
          {
            kpg = (KeyPairGenerator) o;
            kpg.algorithm = algorithm;
          }

        kpg.provider = provider;
        return kpg;
      }
    catch (ClassNotFoundException cnfe)
      {
        throw new NoSuchAlgorithmException("Class not found");
      }
    catch (InstantiationException ie)
      {
        throw new NoSuchAlgorithmException("Class instantiation failed");
      }
    catch (IllegalAccessException iae)
      {
        throw new NoSuchAlgorithmException("Illegal Access");
      }
  }

  /**
     Gets the provider that the class is from.

     @return the provider of this class
   */
  public final Provider getProvider()
  {
    return provider;
  }

  /**
     Initializes the KeyPairGenerator for the specified key size.
     (Since no source of randomness is specified, a default one is
     provided.)

     @param keysize Size of key to generate
   */
  public void initialize(int keysize)
  {
    initialize(keysize, new SecureRandom());
  }

  /**
     Initializes the KeyPairGenerator for the specified key size
     and specified SecureRandom.

     @param keysize Size of key to generate
     @param random SecureRandom to use

     @since JDK 1.2
   */
  public void initialize(int keysize, SecureRandom random)
  {
    initialize(keysize, random);
  }

  /**
     Initializes the KeyPairGenerator with the specified
     AlgorithmParameterSpec class.
     (Since no source of randomness is specified, a default one is
     provided.)

     @param params AlgorithmParameterSpec to initialize with

     @since JDK 1.2
   */
  public void initialize(AlgorithmParameterSpec params)
    throws InvalidAlgorithmParameterException
  {
    initialize(params, new SecureRandom());
  }

  /**
     Initializes the KeyPairGenerator with the specified
     AlgorithmParameterSpec class and specified SecureRandom.

     @param params AlgorithmParameterSpec to initialize with
     @param random SecureRandom to use

     @since JDK 1.2
   */
  public void initialize(AlgorithmParameterSpec params, SecureRandom random)
    throws InvalidAlgorithmParameterException
  {
    super.initialize(params, random);
  }

  /**
     Generates a KeyPair according the rules for the algorithm.
     Unless intialized, algorithm defaults will be used. It 
     creates a unique key pair each time.

     Same as generateKeyPair();

     @return a key pair
   */
  public final KeyPair genKeyPair()
  {
    try
      {
        return getInstance("DSA", "GNU").generateKeyPair();
      }
    catch (Exception e)
      {
        System.err.println("genKeyPair failed: " + e);
        e.printStackTrace();
        return null;
      }
  }

  /**
     Generates a KeyPair according the rules for the algorithm.
     Unless intialized, algorithm defaults will be used. It 
     creates a unique key pair each time.

     Same as genKeyPair();

     @return a key pair
   */
  public KeyPair generateKeyPair()
  {
    return genKeyPair();
  }
}