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    1   /*
    2    * Copyright (c) 1997, 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.spec;
   27   
   28   import java.security.InvalidKeyException;
   29   
   30   /**
   31    * This class specifies a DES-EDE ("triple-DES") key.
   32    *
   33    * @author Jan Luehe
   34    *
   35    * @since 1.4
   36    */
   37   public class DESedeKeySpec implements java.security.spec.KeySpec {
   38   
   39       /**
   40        * The constant which defines the length of a DESede key in bytes.
   41        */
   42       public static final int DES_EDE_KEY_LEN = 24;
   43   
   44       private byte[] key;
   45   
   46       /**
   47        * Creates a DESedeKeySpec object using the first 24 bytes in
   48        * <code>key</code> as the key material for the DES-EDE key.
   49        *
   50        * <p> The bytes that constitute the DES-EDE key are those between
   51        * <code>key[0]</code> and <code>key[23]</code> inclusive
   52        *
   53        * @param key the buffer with the DES-EDE key material. The first
   54        * 24 bytes of the buffer are copied to protect against subsequent
   55        * modification.
   56        *
   57        * @exception NullPointerException if <code>key</code> is null.
   58        * @exception InvalidKeyException if the given key material is shorter
   59        * than 24 bytes.
   60        */
   61       public DESedeKeySpec(byte[] key) throws InvalidKeyException {
   62           this(key, 0);
   63       }
   64   
   65       /**
   66        * Creates a DESedeKeySpec object using the first 24 bytes in
   67        * <code>key</code>, beginning at <code>offset</code> inclusive,
   68        * as the key material for the DES-EDE key.
   69        *
   70        * <p> The bytes that constitute the DES-EDE key are those between
   71        * <code>key[offset]</code> and <code>key[offset+23]</code> inclusive.
   72        *
   73        * @param key the buffer with the DES-EDE key material. The first
   74        * 24 bytes of the buffer beginning at <code>offset</code> inclusive
   75        * are copied to protect against subsequent modification.
   76        * @param offset the offset in <code>key</code>, where the DES-EDE key
   77        * material starts.
   78        *
   79        * @exception NullPointerException if <code>key</code> is null.
   80        * @exception InvalidKeyException if the given key material, starting at
   81        * <code>offset</code> inclusive, is shorter than 24 bytes
   82        */
   83       public DESedeKeySpec(byte[] key, int offset) throws InvalidKeyException {
   84           if (key.length - offset < 24) {
   85               throw new InvalidKeyException("Wrong key size");
   86           }
   87           this.key = new byte[24];
   88           System.arraycopy(key, offset, this.key, 0, 24);
   89       }
   90   
   91       /**
   92        * Returns the DES-EDE key.
   93        *
   94        * @return the DES-EDE key. Returns a new array
   95        * each time this method is called.
   96        */
   97       public byte[] getKey() {
   98           return (byte[])this.key.clone();
   99       }
  100   
  101       /**
  102        * Checks if the given DES-EDE key, starting at <code>offset</code>
  103        * inclusive, is parity-adjusted.
  104        *
  105        * @param key    a byte array which holds the key value
  106        * @param offset the offset into the byte array
  107        * @return true if the given DES-EDE key is parity-adjusted, false
  108        * otherwise
  109        *
  110        * @exception NullPointerException if <code>key</code> is null.
  111        * @exception InvalidKeyException if the given key material, starting at
  112        * <code>offset</code> inclusive, is shorter than 24 bytes
  113        */
  114       public static boolean isParityAdjusted(byte[] key, int offset)
  115           throws InvalidKeyException {
  116               if (key.length - offset < 24) {
  117                   throw new InvalidKeyException("Wrong key size");
  118               }
  119               if (DESKeySpec.isParityAdjusted(key, offset) == false
  120                   || DESKeySpec.isParityAdjusted(key, offset + 8) == false
  121                   || DESKeySpec.isParityAdjusted(key, offset + 16) == false) {
  122                   return false;
  123               }
  124               return true;
  125       }
  126   }

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