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 import java.security.ProviderException;
  30 
  31 /**
  32  * This abstract class represents the core of all block ciphers. It allows to
  33  * intialize the cipher and encrypt/decrypt single blocks. Larger quantities
  34  * are handled by modes, which are subclasses of FeedbackCipher.
  35  *
  36  * @author Gigi Ankeny
  37  * @author Jan Luehe
  38  *
  39  *
  40  * @see AESCrypt
  41  * @see DESCrypt
  42  * @see DESedeCrypt
  43  * @see BlowfishCrypt
  44  * @see FeedbackCipher
  45  */
  46 abstract class SymmetricCipher {
  47 
  48     SymmetricCipher() {
  49         // empty
  50     }
  51 
  52     /**
  53      * Retrieves this cipher's block size.
  54      *
  55      * @return the block size of this cipher
  56      */
  57     abstract int getBlockSize();
  58 
  59     /**
  60      * Initializes the cipher in the specified mode with the given key.
  61      *
  62      * @param decrypting flag indicating encryption or decryption
  63      * @param algorithm the algorithm name
  64      * @param key the key
  65      *
  66      * @exception InvalidKeyException if the given key is inappropriate for
  67      * initializing this cipher
  68      */
  69     abstract void init(boolean decrypting, String algorithm, byte[] key)
  70         throws InvalidKeyException;
  71 
  72     /**
  73      * Encrypt one cipher block.
  74      *
  75      * <p>The input <code>plain</code>, starting at <code>plainOffset</code>
  76      * and ending at <code>(plainOffset+blockSize-1)</code>, is encrypted.
  77      * The result is stored in <code>cipher</code>, starting at
  78      * <code>cipherOffset</code>.
  79      *
  80      * @param plain the input buffer with the data to be encrypted
  81      * @param plainOffset the offset in <code>plain</code>
  82      * @param cipher the buffer for the encryption result
  83      * @param cipherOffset the offset in <code>cipher</code>
  84      */
  85     abstract void encryptBlock(byte[] plain, int plainOffset,
  86                           byte[] cipher, int cipherOffset);
  87 
  88     void encryptBlocks(byte[] plain, int plainOffset, byte[] cipher, int cipherOffset, int len) {
  89         int blockSize = getBlockSize();
  90         if ((len % blockSize) != 0) {
  91             throw new ProviderException("Internal error in input buffering");
  92         }
  93         for (int i = 0; i < len; i += blockSize) {
  94             encryptBlock(plain, plainOffset + i, cipher, cipherOffset + i);
  95         }
  96     }
  97 
  98 
  99     /**
 100      * Decrypt one cipher block.
 101      *
 102      * <p>The input <code>cipher</code>, starting at <code>cipherOffset</code>
 103      * and ending at <code>(cipherOffset+blockSize-1)</code>, is decrypted.
 104      * The result is stored in <code>plain</code>, starting at
 105      * <code>plainOffset</code>.
 106      *
 107      * @param cipher the input buffer with the data to be decrypted
 108      * @param cipherOffset the offset in <code>cipher</code>
 109      * @param plain the buffer for the decryption result
 110      * @param plainOffset the offset in <code>plain</code>
 111      */
 112     abstract void decryptBlock(byte[] cipher, int cipherOffset,
 113                           byte[] plain, int plainOffset);
 114 
 115     void decryptBlocks(byte[] cipher, int cipherOffset, byte[] plain, int plainOffset, int len) {
 116         int blockSize = getBlockSize();
 117         if ((len % blockSize) != 0) {
 118             throw new ProviderException("Internal error in input buffering");
 119         }
 120         for (int i = 0; i < len; i += blockSize) {
 121             decryptBlock(cipher, cipherOffset + i, plain, plainOffset + i);
 122         }
 123     }
 124 
 125 }