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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 com.sun.crypto.provider;
   27   
   28   import java.security.InvalidKeyException;
   29   
   30   /**
   31    * This class implements the Triple DES algorithm (DES encryption, followed by
   32    * DES decryption, followed by DES encryption) on a byte array of size
   33    * <code>DES_BLOCK_SIZE</code>. Each DES operation has its own key.
   34    *
   35    * @author Gigi Ankeny
   36    * @author Jan Luehe
   37    *
   38    *
   39    * @see DESConstants
   40    * @see DESCipher
   41    */
   42   
   43   final class DESedeCrypt extends DESCrypt implements DESConstants {
   44   
   45       /*
   46        * the expanded key used in encrypt/decrypt/encrypt phase
   47        */
   48       private byte[] key1 = null;
   49       private byte[] key2 = null;
   50       private byte[] key3 = null;
   51       private byte[] buf1, buf2;
   52   
   53       /*
   54        * constructor
   55        */
   56       DESedeCrypt() {
   57           buf1 = new byte[DES_BLOCK_SIZE];
   58           buf2 = new byte[DES_BLOCK_SIZE];
   59       }
   60   
   61       void init(boolean decrypting, String algorithm, byte[] keys)
   62               throws InvalidKeyException {
   63           if (!algorithm.equalsIgnoreCase("DESede")
   64                       && !algorithm.equalsIgnoreCase("TripleDES")) {
   65               throw new InvalidKeyException
   66                   ("Wrong algorithm: DESede or TripleDES required");
   67           }
   68           if (keys.length != DES_BLOCK_SIZE * 3) {
   69               throw new InvalidKeyException("Wrong key size");
   70           }
   71   
   72           byte[] keybuf = new byte[DES_BLOCK_SIZE];
   73   
   74           // retrieve the first key
   75           key1 = new byte[128];
   76           System.arraycopy(keys, 0, keybuf, 0, DES_BLOCK_SIZE);
   77           expandKey(keybuf);
   78           System.arraycopy(expandedKey, 0, key1, 0, 128);
   79   
   80           // check if the third key is the same
   81           if (keyEquals(keybuf, 0, keys, DES_BLOCK_SIZE*2, DES_BLOCK_SIZE)) {
   82               key3 = key1;
   83           } else {
   84               key3 = new byte[128];
   85               System.arraycopy(keys, DES_BLOCK_SIZE*2, keybuf, 0,
   86                                DES_BLOCK_SIZE);
   87               expandKey(keybuf);
   88               System.arraycopy(expandedKey, 0, key3, 0, 128);
   89           }
   90   
   91           // retrieve the second key
   92           key2 = new byte[128];
   93           System.arraycopy(keys, DES_BLOCK_SIZE, keybuf, 0, DES_BLOCK_SIZE);
   94           expandKey(keybuf);
   95           System.arraycopy(expandedKey, 0, key2, 0, 128);
   96   
   97       }
   98   
   99       /**
  100        * Performs encryption operation.
  101        *
  102        * <p>The input plain text <code>plain</code>, starting at
  103        * <code>plainOffset</code> and ending at
  104        * <code>(plainOffset + blockSize - 1)</code>, is encrypted.
  105        * The result is stored in <code>cipher</code>, starting at
  106        * <code>cipherOffset</code>.
  107        *
  108        * @param plain the buffer with the input data to be encrypted
  109        * @param plainOffset the offset in <code>plain</code>
  110        * @param cipher the buffer for the result
  111        * @param cipherOffset the offset in <code>cipher</code>
  112        */
  113       void encryptBlock(byte[] plain, int plainOffset,
  114                    byte[] cipher, int cipherOffset)
  115       {
  116           expandedKey = key1;
  117           decrypting = false;
  118           cipherBlock(plain, plainOffset, buf1, 0);
  119   
  120           expandedKey = key2;
  121           decrypting = true;
  122           cipherBlock(buf1, 0, buf2, 0);
  123   
  124           expandedKey = key3;
  125           decrypting = false;
  126           cipherBlock(buf2, 0, cipher, cipherOffset);
  127       }
  128   
  129       /**
  130        * Performs decryption operation.
  131        *
  132        * <p>The input cipher text <code>cipher</code>, starting at
  133        * <code>cipherOffset</code> and ending at
  134        * <code>(cipherOffset + blockSize - 1)</code>, is decrypted.
  135        * The result is stored in <code>plain</code>, starting at
  136        * <code>plainOffset</code>.
  137        *
  138        * @param cipher the buffer with the input data to be decrypted
  139        * @param cipherOffset the offset in <code>cipherOffset</code>
  140        * @param plain the buffer for the result
  141        * @param plainOffset the offset in <code>plain</code>
  142        */
  143       void decryptBlock(byte[] cipher, int cipherOffset,
  144                    byte[] plain, int plainOffset)
  145       {
  146           expandedKey = key3;
  147           decrypting = true;
  148           cipherBlock(cipher, cipherOffset, buf1, 0);
  149   
  150           expandedKey = key2;
  151           decrypting = false;
  152           cipherBlock(buf1, 0, buf2, 0);
  153   
  154           expandedKey = key1;
  155           decrypting = true;
  156           cipherBlock(buf2, 0, plain, plainOffset);
  157       }
  158   
  159       private boolean keyEquals(byte[] key1, int off1,
  160                                 byte[] key2, int off2, int len) {
  161   
  162           for (int i=0; i<len; i++) {
  163               if (key1[i+off1] != key2[i+off2])
  164                   return false;
  165           }
  166           return true;
  167       }
  168   }

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