libjava/classpath/gnu/javax/crypto/prng/PRNGFactory.java

   1 /* PRNGFactory.java --
   2    Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc.
   3
   4 This file is a 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 of the License, or (at
   9 your option) 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; if not, write to the Free Software
  18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19 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 gnu.javax.crypto.prng;
  40
  41 import gnu.java.security.Registry;
  42 import gnu.java.security.prng.IRandom;
  43
  44
  45 import gnu.javax.crypto.mac.IMac;
  46 import gnu.javax.crypto.mac.MacFactory;
  47 import gnu.javax.crypto.mac.HMacFactory;
  48
  49 import java.util.Collections;
  50 import java.util.HashSet;
  51 import java.util.Iterator;
  52 import java.util.Set;
  53
  54 /**
  55  * <p>A Factory to instantiate pseudo random number generators.</p>
  56  */
  57 public class PRNGFactory implements Registry
  58 {
  59
  60   // Constants and variables
  61   // -------------------------------------------------------------------------
  62
  63   // Constructor(s)
  64   // -------------------------------------------------------------------------
  65
  66   /** Trivial constructor to enforce <i>Singleton</i> pattern. */
  67   private PRNGFactory()
  68   {
  69   }
  70
  71   // Class methods
  72   // -------------------------------------------------------------------------
  73
  74   /**
  75    * <p>Returns an instance of a padding algorithm given its name.</p>
  76    *
  77    * @param prng the case-insensitive name of the PRNG.
  78    * @return an instance of the pseudo-random number generator.
  79    * @exception InternalError if the implementation does not pass its self-
  80    * test.
  81    */
  82   public static IRandom getInstance(String prng)
  83   {
  84     if (prng == null)
  85       {
  86         return null;
  87       }
  88
  89     prng = prng.trim();
  90     IRandom result = null;
  91     if (prng.equalsIgnoreCase(ARCFOUR_PRNG) || prng.equalsIgnoreCase(RC4_PRNG))
  92       {
  93         result = new ARCFour();
  94       }
  95     else if (prng.equalsIgnoreCase(ICM_PRNG))
  96       {
  97         result = new ICMGenerator();
  98       }
  99     else if (prng.equalsIgnoreCase(UMAC_PRNG))
 100       {
 101         result = new UMacGenerator();
 102       }
 103     else if (prng.toLowerCase().startsWith(PBKDF2_PRNG_PREFIX))
 104       {
 105         String macName = prng.substring(PBKDF2_PRNG_PREFIX.length());
 106         IMac mac = MacFactory.getInstance(macName);
 107         if (mac == null)
 108           {
 109             return null;
 110           }
 111         result = new PBKDF2(mac);
 112       }
 113
 114     if (result != null)
 115       return result;
 116
 117     return gnu.java.security.prng.PRNGFactory.getInstance (prng);
 118   }
 119
 120   /**
 121    * <p>Returns a {@link Set} of names of padding algorithms supported by this
 122    * <i>Factory</i>.</p>
 123    *
 124    * @return a {@link Set} of pseudo-random number generator algorithm names
 125    * (Strings).
 126    */
 127   public static Set getNames()
 128   {
 129     HashSet hs = new HashSet (gnu.java.security.prng.PRNGFactory.getNames ());
 130     hs.add(ICM_PRNG);
 131     hs.add(UMAC_PRNG);
 132     // add all hmac implementations as candidate PBKDF2 ones too
 133     for (Iterator it = HMacFactory.getNames().iterator(); it.hasNext();)
 134       {
 135         hs.add(PBKDF2_PRNG_PREFIX + ((String) it.next()));
 136       }
 137
 138     return Collections.unmodifiableSet(hs);
 139   }
 140
 141   // Instance methods
 142   // -------------------------------------------------------------------------
 143 }