/*
* Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.crypto.provider;
import java.security.InvalidKeyException;
import javax.crypto.IllegalBlockSizeException;
/**
* This class represents a block cipher in one of its modes. It wraps
* a SymmetricCipher maintaining the mode state and providing
* the capability to encrypt amounts of data larger than a single block.
*
* @author Jan Luehe
* @see ElectronicCodeBook
* @see CipherBlockChaining
* @see CipherFeedback
* @see OutputFeedback
* @see PCBC
*/
abstract class FeedbackCipher {
// the embedded block cipher
final SymmetricCipher embeddedCipher;
// the block size of the embedded block cipher
final int blockSize;
// the initialization vector
byte[] iv;
FeedbackCipher(SymmetricCipher embeddedCipher) {
this.embeddedCipher = embeddedCipher;
blockSize = embeddedCipher.getBlockSize();
}
final SymmetricCipher getEmbeddedCipher() {
return embeddedCipher;
}
/**
* Gets the block size of the embedded cipher.
*
* @return the block size of the embedded cipher
*/
final int getBlockSize() {
return blockSize;
}
/**
* Gets the name of the feedback mechanism
*
* @return the name of the feedback mechanism
*/
abstract String getFeedback();
/**
* Save the current content of this cipher.
*/
abstract void save();
/**
* Restores the content of this cipher to the previous saved one.
*/
abstract void restore();
/**
* Initializes the cipher in the specified mode with the given key
* and iv.
*
* @param decrypting flag indicating encryption or decryption mode
* @param algorithm the algorithm name (never null)
* @param key the key (never null)
* @param iv the iv (either null or blockSize bytes long)
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this cipher
*/
abstract void init(boolean decrypting, String algorithm, byte[] key,
byte[] iv) throws InvalidKeyException;
/**
* Gets the initialization vector.
*
* @return the initialization vector
*/
final byte[] getIV() {
return iv;
}
/**
* Resets the iv to its original value.
* This is used when doFinal is called in the Cipher class, so that the
* cipher can be reused (with its original iv).
*/
abstract void reset();
/**
* Performs encryption operation.
*
* <p>The input <code>plain</code>, starting at <code>plainOffset</code>
* and ending at <code>(plainOffset+plainLen-1)</code>, is encrypted.
* The result is stored in <code>cipher</code>, starting at
* <code>cipherOffset</code>.
*
* <p>The subclass that implements Cipher should ensure that
* <code>init</code> has been called before this method is called.
*
* @param plain the input buffer with the data to be encrypted
* @param plainOffset the offset in <code>plain</code>
* @param plainLen the length of the input data
* @param cipher the buffer for the encryption result
* @param cipherOffset the offset in <code>cipher</code>
*/
abstract void encrypt(byte[] plain, int plainOffset, int plainLen,
byte[] cipher, int cipherOffset);
/**
* Performs encryption operation for the last time.
*
* <p>NOTE: For cipher feedback modes which does not perform
* special handling for the last few blocks, this is essentially
* the same as <code>encrypt(...)</code>. Given most modes do
* not do special handling, the default impl for this method is
* to simply call <code>encrypt(...)</code>.
*
* @param plain the input buffer with the data to be encrypted
* @param plainOffset the offset in <code>plain</code>
* @param plainLen the length of the input data
* @param cipher the buffer for the encryption result
* @param cipherOffset the offset in <code>cipher</code>
*/
void encryptFinal(byte[] plain, int plainOffset, int plainLen,
byte[] cipher, int cipherOffset)
throws IllegalBlockSizeException {
encrypt(plain, plainOffset, plainLen, cipher, cipherOffset);
}
/**
* Performs decryption operation.
*
* <p>The input <code>cipher</code>, starting at <code>cipherOffset</code>
* and ending at <code>(cipherOffset+cipherLen-1)</code>, is decrypted.
* The result is stored in <code>plain</code>, starting at
* <code>plainOffset</code>.
*
* <p>The subclass that implements Cipher should ensure that
* <code>init</code> has been called before this method is called.
*
* @param cipher the input buffer with the data to be decrypted
* @param cipherOffset the offset in <code>cipher</code>
* @param cipherLen the length of the input data
* @param plain the buffer for the decryption result
* @param plainOffset the offset in <code>plain</code>
*/
abstract void decrypt(byte[] cipher, int cipherOffset, int cipherLen,
byte[] plain, int plainOffset);
/**
* Performs decryption operation for the last time.
*
* <p>NOTE: For cipher feedback modes which does not perform
* special handling for the last few blocks, this is essentially
* the same as <code>encrypt(...)</code>. Given most modes do
* not do special handling, the default impl for this method is
* to simply call <code>decrypt(...)</code>.
*
* @param cipher the input buffer with the data to be decrypted
* @param cipherOffset the offset in <code>cipher</code>
* @param cipherLen the length of the input data
* @param plain the buffer for the decryption result
* @param plainOffset the offset in <code>plain</code>
*/
void decryptFinal(byte[] cipher, int cipherOffset, int cipherLen,
byte[] plain, int plainOffset)
throws IllegalBlockSizeException {
decrypt(cipher, cipherOffset, cipherLen, plain, plainOffset);
}
}