/*

 * 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);

     }

}