001    /* MacSpi.java -- The MAC service provider interface.
002       Copyright (C) 2004  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.crypto;
040    
041    import java.nio.ByteBuffer;
042    import java.security.InvalidAlgorithmParameterException;
043    import java.security.InvalidKeyException;
044    import java.security.Key;
045    import java.security.spec.AlgorithmParameterSpec;
046    
047    /**
048     * This is the <i>Service Provider Interface</i> (<b>SPI</b>) for the
049     * {@link Mac} class.
050     *
051     * <p>Providers wishing to implement a Mac must subclass this class and
052     * provide appropriate implementations of all its abstract methods,
053     * then provide an entry pointing to this implementation in the master
054     * {@link java.security.Provider} class.
055     *
056     * <p>Implementations may optionally implement the {@link
057     * java.lang.Cloneable} interface.
058     *
059     * @author Casey Marshall (csm@gnu.org)
060     * @since 1.4
061     */
062    public abstract class MacSpi
063    {
064    
065      // Constructor.
066      // ------------------------------------------------------------------------
067    
068      /**
069       * Create a new MacSpi instance.
070       */
071      public MacSpi()
072      {
073      }
074    
075      // Instance methods.
076      // ------------------------------------------------------------------------
077    
078      /**
079       * Returns a clone of this instance if cloning is supported.
080       *
081       * @return A clone of this instance.
082       * @throws java.lang.CloneNotSupportedException If this instance does
083       *         not support cloneing.
084       */
085      public Object clone() throws CloneNotSupportedException
086      {
087        return super.clone();
088      }
089    
090      // Abstract instance methods.
091      // ------------------------------------------------------------------------
092    
093      /**
094       * Finalize the computation of this MAC and return the result as a
095       * byte array.
096       *
097       * @return The MAC.
098       */
099      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    }