libjava/classpath/gnu/javax/crypto/mode/ModeFactory.java

   1 /* ModeFactory.java --
   2    Copyright (C) 2001, 2002, 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.mode;
  40
  41 import gnu.java.security.Registry;
  42
  43 import gnu.javax.crypto.cipher.CipherFactory;
  44 import gnu.javax.crypto.cipher.IBlockCipher;
  45
  46 import java.util.Collections;
  47 import java.util.HashSet;
  48 import java.util.Iterator;
  49 import java.util.Set;
  50
  51 /**
  52  * <p>A <i>Factory</i> to instantiate block cipher modes of operations.</p>
  53  */
  54 public class ModeFactory implements Registry
  55 {
  56
  57   // Constants and variables
  58   // -------------------------------------------------------------------------
  59
  60   // Constructor(s)
  61   // -------------------------------------------------------------------------
  62
  63   /** Trivial constructor to enforce Singleton pattern. */
  64   private ModeFactory()
  65   {
  66     super();
  67   }
  68
  69   // Class methods
  70   // -------------------------------------------------------------------------
  71
  72   /**
  73    * <p>Returns an instance of a block cipher mode of operations given its name
  74    * and characteristics of the underlying block cipher.</p>
  75    *
  76    * @param mode the case-insensitive name of the mode of operations.
  77    * @param cipher the case-insensitive name of the block cipher.
  78    * @param cipherBlockSize the block size, in bytes, of the underlying cipher.
  79    * @return an instance of the block cipher algorithm, operating in a given
  80    * mode of operations, or <code>null</code> if none found.
  81    * @exception InternalError if either the mode or the underlying block cipher
  82    * implementation does not pass its self-test.
  83    */
  84   public static IMode getInstance(String mode, String cipher,
  85                                   int cipherBlockSize)
  86   {
  87     if (mode == null || cipher == null)
  88       {
  89         return null;
  90       }
  91
  92     mode = mode.trim();
  93     cipher = cipher.trim();
  94
  95     IBlockCipher cipherImpl = CipherFactory.getInstance(cipher);
  96     if (cipherImpl == null)
  97       {
  98         return null;
  99       }
 100
 101     return getInstance(mode, cipherImpl, cipherBlockSize);
 102   }
 103
 104   public static IMode getInstance(String mode, IBlockCipher cipher,
 105                                   int cipherBlockSize)
 106   {
 107     // ensure that cipherBlockSize is valid for the chosen underlying cipher
 108     boolean ok = false;
 109     for (Iterator it = cipher.blockSizes(); it.hasNext();)
 110       {
 111         ok = (cipherBlockSize == ((Integer) it.next()).intValue());
 112         if (ok)
 113           {
 114             break;
 115           }
 116       }
 117
 118     if (!ok)
 119       {
 120         throw new IllegalArgumentException("cipherBlockSize");
 121       }
 122
 123     IMode result = null;
 124     if (mode.equalsIgnoreCase(ECB_MODE))
 125       {
 126         result = new ECB(cipher, cipherBlockSize);
 127       }
 128     else if (mode.equalsIgnoreCase(CTR_MODE))
 129       {
 130         result = new CTR(cipher, cipherBlockSize);
 131       }
 132     else if (mode.equalsIgnoreCase(ICM_MODE))
 133       {
 134         result = new ICM(cipher, cipherBlockSize);
 135       }
 136     else if (mode.equalsIgnoreCase(OFB_MODE))
 137       {
 138         result = new OFB(cipher, cipherBlockSize);
 139       }
 140     else if (mode.equalsIgnoreCase(CBC_MODE))
 141       {
 142         result = new CBC(cipher, cipherBlockSize);
 143       }
 144     else if (mode.equalsIgnoreCase(CFB_MODE))
 145       {
 146         result = new CFB(cipher, cipherBlockSize);
 147       }
 148     else if (mode.equalsIgnoreCase(EAX_MODE))
 149       {
 150         result = new EAX(cipher, cipherBlockSize);
 151       }
 152
 153     if (result != null && !result.selfTest())
 154       {
 155         throw new InternalError(result.name());
 156       }
 157
 158     return result;
 159   }
 160
 161   /**
 162    * <p>Returns a {@link java.util.Set} of names of mode supported by this
 163    * <i>Factory</i>.</p>
 164    *
 165    * @return a {@link java.util.Set} of mode names (Strings).
 166    */
 167   public static final Set getNames()
 168   {
 169     synchronized (ModeFactory.class)
 170       {
 171         if (names == null)
 172           {
 173             HashSet hs = new HashSet();
 174             hs.add(ECB_MODE);
 175             hs.add(CTR_MODE);
 176             hs.add(ICM_MODE);
 177             hs.add(OFB_MODE);
 178             hs.add(CBC_MODE);
 179             hs.add(CFB_MODE);
 180             hs.add(EAX_MODE);
 181
 182             names = Collections.unmodifiableSet(hs);
 183           }
 184       }
 185     return names;
 186   }
 187
 188   private static Set names;
 189
 190   // Instance methods
 191   // -------------------------------------------------------------------------
 192 }