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	/*
	* Copyright (c) 1997, 2017, 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 java.security.InvalidAlgorithmParameterException;
	import javax.crypto.*;

	/**
	* 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,
	InvalidAlgorithmParameterException;

	/**
	* 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>
	* @return the number of bytes placed into <code>cipher</code>
	*/
	abstract int 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>
	* @return the number of bytes placed into <code>cipher</code>
	*/
	int encryptFinal(byte[] plain, int plainOffset, int plainLen,
	byte[] cipher, int cipherOffset)
	throws IllegalBlockSizeException, ShortBufferException {
	return 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>
	* @return the number of bytes placed into <code>plain</code>
	*/
	abstract int 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>
	* @return the number of bytes placed into <code>plain</code>
	*/
	int decryptFinal(byte[] cipher, int cipherOffset, int cipherLen,
	byte[] plain, int plainOffset)
	throws IllegalBlockSizeException, AEADBadTagException,
	ShortBufferException {
	return decrypt(cipher, cipherOffset, cipherLen, plain, plainOffset);
	}

	/**
	* Continues a multi-part update of the Additional Authentication
	* Data (AAD), using a subset of the provided buffer. If this
	* cipher is operating in either GCM or CCM mode, all AAD must be
	* supplied before beginning operations on the ciphertext (via the
	* {@code update} and {@code doFinal} methods).
	* <p>
	* NOTE: Given most modes do not accept AAD, default impl for this
	* method throws IllegalStateException.
	*
	* @param src the buffer containing the AAD
	* @param offset the offset in {@code src} where the AAD input starts
	* @param len the number of AAD bytes
	*
	* @throws IllegalStateException if this cipher is in a wrong state
	* (e.g., has not been initialized), does not accept AAD, or if
	* operating in either GCM or CCM mode and one of the {@code update}
	* methods has already been called for the active
	* encryption/decryption operation
	* @throws UnsupportedOperationException if this method
	* has not been overridden by an implementation
	*
	* @since 1.8
	*/
	void updateAAD(byte[] src, int offset, int len) {
	throw new IllegalStateException("No AAD accepted");
	}

	/**
	* @return the number of bytes that are buffered internally inside
	* this FeedbackCipher instance.
	* @since 1.8
	*/
	int getBufferedLength() {
	// Currently only AEAD cipher impl, e.g. GCM, buffers data
	// internally during decryption mode
	return 0;
	}
	}

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