1 /*

     2  * Copyright 1998-2007 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package javax.crypto;

    27 

    28 import java.security.*;

    29 import java.security.spec.*;

    30 

    31 import java.nio.ByteBuffer;

    32 

    33 /**

    34  * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)

    35  * for the <code>Mac</code> class.

    36  * All the abstract methods in this class must be implemented by each

    37  * cryptographic service provider who wishes to supply the implementation

    38  * of a particular MAC algorithm.

    39  *

    40  * <p> Implementations are free to implement the Cloneable interface.

    41  *

    42  * @author Jan Luehe

    43  *

    44  * @since 1.4

    45  */

    46 

    47 public abstract class MacSpi {

    48 

    49     /**

    50      * Returns the length of the MAC in bytes.

    51      *

    52      * @return the MAC length in bytes.

    53      */

    54     protected abstract int engineGetMacLength();

    55 

    56     /**

    57      * Initializes the MAC with the given (secret) key and algorithm

    58      * parameters.

    59      *

    60      * @param key the (secret) key.

    61      * @param params the algorithm parameters.

    62      *

    63      * @exception InvalidKeyException if the given key is inappropriate for

    64      * initializing this MAC.

    65      * @exception InvalidAlgorithmParameterException if the given algorithm

    66      * parameters are inappropriate for this MAC.

    67      */

    68     protected abstract void engineInit(Key key,

    69                                        AlgorithmParameterSpec params)

    70         throws InvalidKeyException, InvalidAlgorithmParameterException ;

    71 

    72     /**

    73      * Processes the given byte.

    74      *

    75      * @param input the input byte to be processed.

    76      */

    77     protected abstract void engineUpdate(byte input);

    78 

    79     /**

    80      * Processes the first <code>len</code> bytes in <code>input</code>,

    81      * starting at <code>offset</code> inclusive.

    82      *

    83      * @param input the input buffer.

    84      * @param offset the offset in <code>input</code> where the input starts.

    85      * @param len the number of bytes to process.

    86      */

    87     protected abstract void engineUpdate(byte[] input, int offset, int len);

    88 

    89     /**

    90      * Processes <code>input.remaining()</code> bytes in the ByteBuffer

    91      * <code>input</code>, starting at <code>input.position()</code>.

    92      * Upon return, the buffer's position will be equal to its limit;

    93      * its limit will not have changed.

    94      *

    95      * <p>Subclasses should consider overriding this method if they can

    96      * process ByteBuffers more efficiently than byte arrays.

    97      *

    98      * @param input the ByteBuffer

    99      * @since 1.5

   100      */

   101     protected void engineUpdate(ByteBuffer input) {

   102         if (input.hasRemaining() == false) {

   103             return;

   104         }

   105         if (input.hasArray()) {

   106             byte[] b = input.array();

   107             int ofs = input.arrayOffset();

   108             int pos = input.position();

   109             int lim = input.limit();

   110             engineUpdate(b, ofs + pos, lim - pos);

   111             input.position(lim);

   112         } else {

   113             int len = input.remaining();

   114             byte[] b = new byte[CipherSpi.getTempArraySize(len)];

   115             while (len > 0) {

   116                 int chunk = Math.min(len, b.length);

   117                 input.get(b, 0, chunk);

   118                 engineUpdate(b, 0, chunk);

   119                 len -= chunk;

   120             }

   121         }

   122     }

   123 

   124     /**

   125      * Completes the MAC computation and resets the MAC for further use,

   126      * maintaining the secret key that the MAC was initialized with.

   127      *

   128      * @return the MAC result.

   129      */

   130     protected abstract byte[] engineDoFinal();

   131 

   132     /**

   133      * Resets the MAC for further use, maintaining the secret key that the

   134      * MAC was initialized with.

   135      */

   136     protected abstract void engineReset();

   137 

   138     /**

   139      * Returns a clone if the implementation is cloneable.

   140      *

   141      * @return a clone if the implementation is cloneable.

   142      *

   143      * @exception CloneNotSupportedException if this is called

   144      * on an implementation that does not support <code>Cloneable</code>.

   145      */

   146     public Object clone() throws CloneNotSupportedException {

   147         if (this instanceof Cloneable) {

   148             return super.clone();

   149         } else {

   150             throw new CloneNotSupportedException();

   151         }

   152     }

   153 }