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    1   /*
    2    * Copyright (c) 1998, 2007, Oracle and/or its affiliates. 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.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * 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   }

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