KeyWrappingAlgorithmFactory.java

/* KeyWrappingAlgorithmFactory.java -- FIXME: briefly describe file purpose
   Copyright (C) 2006 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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02110-1301 USA.

Linking this library statically or dynamically with other modules is
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permission to link this library with independent modules to produce an
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package gnu.javax.crypto.kwa;

import gnu.java.security.Registry;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * A Factory class for the Key Wrapping Algorithm implementations.
 */
public class KeyWrappingAlgorithmFactory
{
  /** Names of Key Wrapping Algorihms cached for speed. */
  private static Set names;
  
  /** Trivial constructor to enforce Singleton pattern. */
  private KeyWrappingAlgorithmFactory()
  {
    super();
  }

  /**
   * Returns an instance of a key-wrapping algorithm given its name.
   * 
   * @param name the case-insensitive name of the key-wrapping algorithm.
   * @return an instance of the designated key-wrapping algorithm, or
   *         <code>null</code> if none was found.
   * @exception InternalError if the implementation does not pass its self-test.
   */
  public static final IKeyWrappingAlgorithm getInstance(String name)
  {
    if (name == null)
      return null;
    name = name.trim();
    IKeyWrappingAlgorithm result = null;
    if (name.equalsIgnoreCase(Registry.AES_KWA)
        || name.equalsIgnoreCase(Registry.AES128_KWA)
        || name.equalsIgnoreCase(Registry.AES192_KWA)
        || name.equalsIgnoreCase(Registry.AES256_KWA)
        || name.equalsIgnoreCase(Registry.RIJNDAEL_KWA))
      result = new AESKeyWrap();
    else if (name.equalsIgnoreCase(Registry.TRIPLEDES_KWA)
        || name.equalsIgnoreCase(Registry.DESEDE_KWA))
      result = new TripleDESKeyWrap();

    return result;
  }

  /**
   * Returns a {@link Set} of key wrapping algorithm names supported by this
   * <i>Factory</i>.
   * 
   * @return a {@link Set} of key wrapping algorithm names (Strings).
   */
  public static synchronized final Set getNames()
  {
    if (names == null)
      {
        HashSet hs = new HashSet();
        hs.add(Registry.AES_KWA);
        hs.add(Registry.AES128_KWA);
        hs.add(Registry.AES192_KWA);
        hs.add(Registry.AES256_KWA);
        hs.add(Registry.RIJNDAEL_KWA);
        hs.add(Registry.TRIPLEDES_KWA);
        hs.add(Registry.DESEDE_KWA);
        names = Collections.unmodifiableSet(hs);
      }
    return names;
  }
}