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 }