libjava/classpath/gnu/java/security/jce/hash/MessageDigestAdapter.java

   1 /* MessageDigestAdapter.java --
   2    Copyright (C) 2001, 2002, 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.java.security.jce.hash;
  40
  41 import gnu.java.security.hash.IMessageDigest;
  42 import gnu.java.security.hash.HashFactory;
  43
  44 import java.security.DigestException;
  45 import java.security.MessageDigestSpi;
  46
  47 /**
  48  * The implementation of a generic {@link java.security.MessageDigest} adapter
  49  * class to wrap gnu.crypto hash instances.<p>
  50  *
  51  * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>) for the
  52  * {@link java.security.MessageDigest} class, which provides the functionality
  53  * of a message digest algorithm, such as MD5 or SHA. Message digests are secure
  54  * one-way hash functions that take arbitrary-sized data and output a fixed-
  55  * length hash value.<p>
  56  *
  57  * All the abstract methods in the {@link java.security.MessageDigestSpi} class
  58  * are implemented by this class and all its sub-classes.<p>
  59  *
  60  * All the implementations which subclass this object, and which are serviced by
  61  * the GNU Crypto provider implement the {@link java.lang.Cloneable} interface.<p>
  62  */
  63 class MessageDigestAdapter extends MessageDigestSpi implements Cloneable
  64 {
  65
  66   // Constants and variables
  67   // -------------------------------------------------------------------------
  68
  69   /** Our underlying hash instance. */
  70   private IMessageDigest adaptee;
  71
  72   // Constructor(s)
  73   // -------------------------------------------------------------------------
  74
  75   /**
  76    * Trivial protected constructor.
  77    *
  78    * @param mdName the canonical name of the hash algorithm.
  79    */
  80   protected MessageDigestAdapter(String mdName)
  81   {
  82     this(HashFactory.getInstance(mdName));
  83   }
  84
  85   /**
  86    * Private constructor for cloning purposes.
  87    *
  88    * @param adaptee a clone of the underlying hash algorithm instance.
  89    */
  90   private MessageDigestAdapter(IMessageDigest adaptee)
  91   {
  92     super();
  93
  94     this.adaptee = adaptee;
  95   }
  96
  97   // Class methods
  98   // -------------------------------------------------------------------------
  99
 100   // java.security.MessageDigestSpi interface implementation
 101   // -------------------------------------------------------------------------
 102
 103   public Object clone()
 104   {
 105     return new MessageDigestAdapter((IMessageDigest) adaptee.clone());
 106   }
 107
 108   public int engineGetDigestLength()
 109   {
 110     return adaptee.hashSize();
 111   }
 112
 113   public void engineUpdate(byte input)
 114   {
 115     adaptee.update(input);
 116   }
 117
 118   public void engineUpdate(byte[] input, int offset, int len)
 119   {
 120     adaptee.update(input, offset, len);
 121   }
 122
 123   public byte[] engineDigest()
 124   {
 125     return adaptee.digest();
 126   }
 127
 128   public int engineDigest(byte[] buf, int offset, int len)
 129       throws DigestException
 130   {
 131     int result = adaptee.hashSize();
 132     if (len < result)
 133       {
 134         throw new DigestException();
 135       }
 136     byte[] md = adaptee.digest();
 137     System.arraycopy(md, 0, buf, offset, result);
 138     return result;
 139   }
 140
 141   public void engineReset()
 142   {
 143     adaptee.reset();
 144   }
 145 }