Source for gnu.javax.crypto.prng.PRNGFactory

   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: import gnu.javax.crypto.mac.HMacFactory;
  44: import gnu.javax.crypto.mac.IMac;
  45: import gnu.javax.crypto.mac.MacFactory;
  46: 
  47: import java.util.Collections;
  48: import java.util.HashSet;
  49: import java.util.Iterator;
  50: import java.util.Set;
  51: 
  52: /**
  53:  * A Factory to instantiate pseudo random number generators.
  54:  */
  55: public class PRNGFactory
  56:     implements Registry
  57: {
  58:   /** Trivial constructor to enforce <i>Singleton</i> pattern. */
  59:   private PRNGFactory()
  60:   {
  61:   }
  62: 
  63:   /**
  64:    * Returns an instance of a padding algorithm given its name.
  65:    *
  66:    * @param prng the case-insensitive name of the PRNG.
  67:    * @return an instance of the pseudo-random number generator.
  68:    * @exception InternalError if the implementation does not pass its self-
  69:    *              test.
  70:    */
  71:   public static IRandom getInstance(String prng)
  72:   {
  73:     if (prng == null)
  74:       return null;
  75:     prng = prng.trim();
  76:     IRandom result = null;
  77:     if (prng.equalsIgnoreCase(ARCFOUR_PRNG) || prng.equalsIgnoreCase(RC4_PRNG))
  78:       result = new ARCFour();
  79:     else if (prng.equalsIgnoreCase(ICM_PRNG))
  80:       result = new ICMGenerator();
  81:     else if (prng.equalsIgnoreCase(UMAC_PRNG))
  82:       result = new UMacGenerator();
  83:     else if (prng.toLowerCase().startsWith(PBKDF2_PRNG_PREFIX))
  84:       {
  85:         String macName = prng.substring(PBKDF2_PRNG_PREFIX.length());
  86:         IMac mac = MacFactory.getInstance(macName);
  87:         if (mac == null)
  88:           return null;
  89:         result = new PBKDF2(mac);
  90:       }
  91: 
  92:     if (result != null)
  93:       return result;
  94: 
  95:     return gnu.java.security.prng.PRNGFactory.getInstance(prng);
  96:   }
  97: 
  98:   /**
  99:    * Returns a {@link Set} of names of padding algorithms supported by this
 100:    * <i>Factory</i>.
 101:    *
 102:    * @return a {@link Set} of pseudo-random number generator algorithm names
 103:    *         (Strings).
 104:    */
 105:   public static Set getNames()
 106:   {
 107:     HashSet hs = new HashSet(gnu.java.security.prng.PRNGFactory.getNames());
 108:     hs.add(ICM_PRNG);
 109:     hs.add(UMAC_PRNG);
 110:     // add all hmac implementations as candidate PBKDF2 ones too
 111:     for (Iterator it = HMacFactory.getNames().iterator(); it.hasNext();)
 112:       hs.add(PBKDF2_PRNG_PREFIX + ((String) it.next()));
 113:     return Collections.unmodifiableSet(hs);
 114:   }
 115: }