Source for gnu.javax.crypto.pad.PadFactory

   1: /* PadFactory.java --
   2:    Copyright (C) 2001, 2002, 2003, 2004, 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.pad;
  40: 
  41: import gnu.java.security.Registry;
  42: 
  43: import java.util.Collections;
  44: import java.util.HashSet;
  45: import java.util.Set;
  46: 
  47: /**
  48:  * A Factory to instantiate padding schemes.
  49:  */
  50: public class PadFactory
  51:     implements Registry
  52: {
  53:   /** Collection of padding algorithm names --cached for speed. */
  54:   private static Set names;
  55: 
  56:   /** Trivial constructor to enforce Singleton pattern. */
  57:   private PadFactory()
  58:   {
  59:     super();
  60:   }
  61: 
  62:   /**
  63:    * Returns an instance of a padding algorithm given its name.
  64:    *
  65:    * @param pad the case-insensitive name of the padding algorithm.
  66:    * @return an instance of the padding algorithm, operating with a given block
  67:    *         size, or <code>null</code> if none found.
  68:    * @throws InternalError if the implementation does not pass its self-test.
  69:    */
  70:   public static final IPad getInstance(String pad)
  71:   {
  72:     if (pad == null)
  73:       return null;
  74: 
  75:     pad = pad.trim().toLowerCase();
  76:     if (pad.endsWith("padding"))
  77:       pad = pad.substring(0, pad.length() - "padding".length());
  78:     IPad result = null;
  79:     if (pad.equals(PKCS7_PAD) || pad.equals(PKCS5_PAD))
  80:       result = new PKCS7();
  81:     else if (pad.equals(TBC_PAD))
  82:       result = new TBC();
  83:     else if (pad.equals(EME_PKCS1_V1_5_PAD))
  84:       result = new PKCS1_V1_5();
  85:     else if (pad.equals(SSL3_PAD))
  86:       result = new SSL3();
  87:     else if (pad.equals(TLS1_PAD))
  88:       result = new TLS1();
  89:     else if (pad.equals(ISO10126_PAD))
  90:       result = new ISO10126();
  91: 
  92:     if (result != null && ! result.selfTest())
  93:       throw new InternalError(result.name());
  94: 
  95:     return result;
  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 padding algorithm names (Strings).
 103:    */
 104:   public static final Set getNames()
 105:   {
 106:     if (names == null)
 107:       {
 108:         HashSet hs = new HashSet();
 109:         hs.add(PKCS5_PAD);
 110:         hs.add(PKCS7_PAD);
 111:         hs.add(TBC_PAD);
 112:         hs.add(EME_PKCS1_V1_5_PAD);
 113:         hs.add(SSL3_PAD);
 114:         hs.add(TLS1_PAD);
 115:         hs.add(ISO10126_PAD);
 116:         names = Collections.unmodifiableSet(hs);
 117:       }
 118:     return names;
 119:   }
 120: }