gcc/libjava/classpath/gnu/javax/crypto/mac/MacFactory.java

/* MacFactory.java -- 
   Copyright (C) 2001, 2002, 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.

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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
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permission to link this library with independent modules to produce an
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package gnu.javax.crypto.mac;

import gnu.java.security.Registry;
import gnu.javax.crypto.cipher.CipherFactory;
import gnu.javax.crypto.cipher.IBlockCipher;

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

/**
 * <p>A <i>Factory</i> that instantiates instances of every supported Message
 * Authentication Code algorithms, including all <i>HMAC</i> algorithms.</p>
 */
public class MacFactory implements Registry
{

  // Constants and variables
  // -------------------------------------------------------------------------

  // Constructor(s)
  // -------------------------------------------------------------------------

  /** Trivial constructor to enforce <i>Singleton</i> pattern. */
  private MacFactory()
  {
    super();
  }

  // Class methods
  // -------------------------------------------------------------------------

  /**
   * <p>Returns an instance of a <i>MAC</i> algorithm given its name.</p>
   *
   * @param name the name of the MAC algorithm.
   * @return an instance of the <i>MAC</i> algorithm, or <code>null</code> if
   * none can be constructed.
   * @exception InternalError if the implementation does not pass its self-test.
   */
  public static IMac getInstance(String name)
  {
    if (name == null)
      {
        return null;
      }

    name = name.trim();
    name = name.toLowerCase();
    if (name.startsWith(HMAC_NAME_PREFIX))
      {
        return HMacFactory.getInstance(name);
      }

    if (name.startsWith(OMAC_PREFIX))
      {
        name = name.substring(OMAC_PREFIX.length());
        IBlockCipher cipher = CipherFactory.getInstance(name);
        if (cipher == null)
          {
            return null;
          }
        return new OMAC(cipher);
      }

    IMac result = null;
    if (name.equalsIgnoreCase(UHASH32))
      {
        result = new UHash32();
      }
    else if (name.equalsIgnoreCase(UMAC32))
      {
        result = new UMac32();
      }
    else if (name.equalsIgnoreCase(TMMH16))
      {
        result = new TMMH16();
      }
    //      else if (name.equalsIgnoreCase(TMMH32)) {
    //         result = new TMMH32();
    //      }

    if (result != null && !result.selfTest())
      {
        throw new InternalError(result.name());
      }

    return result;
  }

  /**
   * <p>Returns a {@link java.util.Set} of names of <i>MAC</i> algorithms
   * supported by this <i>Factory</i>.</p>
   *
   * @return a {@link java.util.Set} of MAC names (Strings).
   */
  public static final Set getNames()
  {
    synchronized (MacFactory.class)
      {
        if (names == null)
          {
            HashSet hs = new HashSet();
            hs.addAll(HMacFactory.getNames());
            hs.add(UHASH32);
            hs.add(UMAC32);
            hs.add(TMMH16);
            //      hs.add(TMMH32);

            for (Iterator it = CipherFactory.getNames().iterator(); it.hasNext();)
              {
                hs.add(OMAC_PREFIX + it.next());
              }

            names = Collections.unmodifiableSet(hs);
          }
      }
    return names;
  }

  private static Set names;

  // Instance methods
  // -------------------------------------------------------------------------
}