001/* MacSpi.java -- The MAC service provider interface.
002   Copyright (C) 2004  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package javax.crypto;
040
041import java.nio.ByteBuffer;
042import java.security.InvalidAlgorithmParameterException;
043import java.security.InvalidKeyException;
044import java.security.Key;
045import 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 */
062public 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}