gcc/libjava/classpath/gnu/java/security/key/KeyPairGeneratorFactory.java

/* KeyPairGeneratorFactory.java -- 
   Copyright 2001, 2002, 2003, 2006 Free Software Foundation, Inc.

This file is a 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
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
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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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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 gnu.java.security.key;

import gnu.java.security.Registry;
import gnu.java.security.key.dss.DSSKeyPairGenerator;
import gnu.java.security.key.rsa.RSAKeyPairGenerator;

import java.lang.reflect.Constructor;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * A Factory to instantiate asymmetric keypair generators.
 */
public class KeyPairGeneratorFactory
{
  /** Trivial constructor to enforce Singleton pattern. */
  private KeyPairGeneratorFactory()
  {
    super();
  }

  /**
   * Returns an instance of a keypair generator given its name.
   * 
   * @param name the case-insensitive key generator name.
   * @return an instance of the keypair generator, or <code>null</code> if
   *         none found.
   */
  public static IKeyPairGenerator getInstance(String name)
  {
    if (name == null)
      return null;

    name = name.trim();
    IKeyPairGenerator result = null;
    if (name.equalsIgnoreCase(Registry.DSA_KPG)
        || name.equalsIgnoreCase(Registry.DSS_KPG))
      result = new DSSKeyPairGenerator();
    else if (name.equalsIgnoreCase(Registry.RSA_KPG))
      result = new RSAKeyPairGenerator();
    else if (name.equalsIgnoreCase(Registry.DH_KPG))
      result = makeInstance("gnu.javax.crypto.key.dh.GnuDHKeyPairGenerator");
    else if (name.equalsIgnoreCase(Registry.SRP_KPG))
      result = makeInstance("gnu.javax.crypto.key.srp6.SRPKeyPairGenerator");

    return result;
  }

  /**
   * Returns a {@link Set} of keypair generator names supported by this
   * <i>Factory</i>. Those keypair generators may be used in conjunction with
   * the digital signature schemes with appendix supported by this library.
   * 
   * @return a {@link Set} of keypair generator names (Strings).
   */
  public static final Set getNames()
  {
    HashSet hs = new HashSet();
    hs.add(Registry.DSS_KPG);
    hs.add(Registry.DSA_KPG);
    hs.add(Registry.RSA_KPG);
    hs.add(Registry.DH_KPG);
    hs.add(Registry.SRP_KPG);
    return Collections.unmodifiableSet(hs);
  }

  private static IKeyPairGenerator makeInstance(String clazz)
  {
    try
      {
        Class c = Class.forName(clazz);
        Constructor ctor = c.getConstructor(new Class[0]);
        return (IKeyPairGenerator) ctor.newInstance(new Object[0]);
      }
    catch (Exception x)
      {
        throw new IllegalArgumentException(
            "strong crypto key pair generator not available: " + clazz, x);
      }
  }
}