Source for javax.crypto.MacSpi

   1: /* MacSpi.java -- The MAC service provider interface.
   2:    Copyright (C) 2004  Free Software Foundation, Inc.
   3: 
   4: This file is 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, or (at your option)
   9: 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; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 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 javax.crypto;
  40: 
  41: import java.nio.ByteBuffer;
  42: import java.security.InvalidAlgorithmParameterException;
  43: import java.security.InvalidKeyException;
  44: import java.security.Key;
  45: import java.security.spec.AlgorithmParameterSpec;
  46: 
  47: /**
  48:  * This is the <i>Service Provider Interface</i> (<b>SPI</b>) for the
  49:  * {@link Mac} class.
  50:  *
  51:  * <p>Providers wishing to implement a Mac must subclass this class and
  52:  * provide appropriate implementations of all its abstract methods,
  53:  * then provide an entry pointing to this implementation in the master
  54:  * {@link java.security.Provider} class.
  55:  *
  56:  * <p>Implementations may optionally implement the {@link
  57:  * java.lang.Cloneable} interface.
  58:  *
  59:  * @author Casey Marshall (csm@gnu.org)
  60:  * @since 1.4
  61:  */
  62: public abstract class MacSpi
  63: {
  64: 
  65:   // Constructor.
  66:   // ------------------------------------------------------------------------
  67: 
  68:   /**
  69:    * Create a new MacSpi instance.
  70:    */
  71:   public MacSpi()
  72:   {
  73:   }
  74: 
  75:   // Instance methods.
  76:   // ------------------------------------------------------------------------
  77: 
  78:   /**
  79:    * Returns a clone of this instance if cloning is supported.
  80:    *
  81:    * @return A clone of this instance.
  82:    * @throws java.lang.CloneNotSupportedException If this instance does
  83:    *         not support cloneing.
  84:    */
  85:   public Object clone() throws CloneNotSupportedException
  86:   {
  87:     return super.clone();
  88:   }
  89: 
  90:   // Abstract instance methods.
  91:   // ------------------------------------------------------------------------
  92: 
  93:   /**
  94:    * Finalize the computation of this MAC and return the result as a
  95:    * byte array.
  96:    *
  97:    * @return The MAC.
  98:    */
  99:   protected abstract byte[] engineDoFinal();
 100: 
 101:   /**
 102:    * Return the total length, in bytes, of the computed MAC (the length
 103:    * of the byte array returned by {@link #doFinal()}.
 104:    *
 105:    * @return The MAC length.
 106:    */
 107:   protected abstract int engineGetMacLength();
 108: 
 109:   /**
 110:    * Initialize (or re-initialize) this instance.
 111:    *
 112:    * @param key    The key to use.
 113:    * @param params The parameters to use.
 114:    * @throws java.security.InvalidAlgorithmParameterException If this
 115:    *         instance rejects the specified parameters.
 116:    * @throws java.security.InvalidKeyException If this instance rejects
 117:    *         the specified key.
 118:    */
 119:   protected abstract void engineInit(Key key, AlgorithmParameterSpec params)
 120:     throws InvalidAlgorithmParameterException, InvalidKeyException;
 121: 
 122:   /**
 123:    * Reset this instance. After this method succeeds, the state of this
 124:    * instance should be the same as it was before any data was input
 125:    * (possibly after a call to {@link
 126:    * #init(java.security.Key,java.security.spec.AlgorithmParameterSpec)},
 127:    * possibly not).
 128:    */
 129:   protected abstract void engineReset();
 130: 
 131:   /**
 132:    * Update this MAC with a single byte.
 133:    *
 134:    * @param input The next byte.
 135:    */
 136:   protected abstract void engineUpdate(byte input);
 137: 
 138:   /**
 139:    * Update this MAC with a portion of a byte array.
 140:    *
 141:    * @param input  The next bytes.
 142:    * @param offset The index in <code>input</code> at which to start.
 143:    * @param length The number of bytes to update.
 144:    */
 145:   protected abstract void engineUpdate(byte[] input, int offset, int length);
 146: 
 147:   /**
 148:    * Update this MAC with the remaining bytes of a buffer.
 149:    *
 150:    * @param buffer The input buffer.
 151:    * @since 1.5
 152:    */
 153:   protected void engineUpdate (final ByteBuffer buffer)
 154:   {
 155:     byte[] buf = new byte[1024];
 156:     while (buffer.hasRemaining ())
 157:       {
 158:         int n = Math.min (buffer.remaining (), buf.length);
 159:         buffer.get (buf, 0, n);
 160:         engineUpdate (buf, 0, n);
 161:       }
 162:   }
 163: }