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	/*
	* Copyright (c) 2002, 2021, 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.util.Arrays;
	import java.util.Locale;

	import java.security.*;
	import java.security.spec.*;
	import javax.crypto.*;
	import javax.crypto.spec.*;
	import javax.crypto.BadPaddingException;

	/**
	* This class represents the symmetric algorithms in its various modes
	* (<code>ECB</code>, <code>CFB</code>, <code>OFB</code>, <code>CBC</code>,
	* <code>PCBC</code>, <code>CTR</code>, and <code>CTS</code>) and
	* padding schemes (<code>PKCS5Padding</code>, <code>NoPadding</code>,
	* <code>ISO10126Padding</code>).
	*
	* @author Gigi Ankeny
	* @author Jan Luehe
	* @see ElectronicCodeBook
	* @see CipherFeedback
	* @see OutputFeedback
	* @see CipherBlockChaining
	* @see PCBC
	* @see CounterMode
	* @see CipherTextStealing
	*/

	final class CipherCore {

	/*
	* internal buffer
	*/
	private byte[] buffer = null;

	/*
	* block size of cipher in bytes
	*/
	private int blockSize = 0;

	/*
	* unit size (number of input bytes that can be processed at a time)
	*/
	private int unitBytes = 0;

	/*
	* index of the content size left in the buffer
	*/
	private int buffered = 0;

	/*
	* minimum number of bytes in the buffer required for
	* FeedbackCipher.encryptFinal()/decryptFinal() call.
	* update() must buffer this many bytes before starting
	* to encrypt/decrypt data.
	* currently, only the following cases have non-zero values:
	* 1) CTS mode - due to its special handling on the last two blocks
	* (the last one may be incomplete).
	*/
	private int minBytes = 0;

	/*
	* number of bytes needed to make the total input length a multiple
	* of the blocksize (this is used in feedback mode, when the number of
	* input bytes that are processed at a time is different from the block
	* size)
	*/
	private int diffBlocksize = 0;

	/*
	* padding class
	*/
	private Padding padding = null;

	/*
	* internal cipher engine
	*/
	private FeedbackCipher cipher = null;

	/*
	* the cipher mode
	*/
	private int cipherMode = ECB_MODE;

	/*
	* are we encrypting or decrypting?
	*/
	private boolean decrypting = false;

	/*
	* Block Mode constants
	*/
	private static final int ECB_MODE = 0;
	private static final int CBC_MODE = 1;
	private static final int CFB_MODE = 2;
	private static final int OFB_MODE = 3;
	private static final int PCBC_MODE = 4;
	private static final int CTR_MODE = 5;
	private static final int CTS_MODE = 6;

	/**
	* Creates an instance of CipherCore with default ECB mode and
	* PKCS5Padding.
	*/
	CipherCore(SymmetricCipher impl, int blkSize) {
	blockSize = blkSize;
	unitBytes = blkSize;
	diffBlocksize = blkSize;

	/*
	* The buffer should be usable for all cipher mode and padding
	* schemes. Thus, it has to be at least (blockSize+1) for CTS.
	* In decryption mode, it also hold the possible padding block.
	*/
	buffer = new byte[blockSize*2];

	// set mode and padding
	cipher = new ElectronicCodeBook(impl);
	padding = new PKCS5Padding(blockSize);
	}

	/**
	* Sets the mode of this cipher.
	*
	* @param mode the cipher mode
	*
	* @exception NoSuchAlgorithmException if the requested cipher mode does
	* not exist for this cipher
	*/
	void setMode(String mode) throws NoSuchAlgorithmException {
	if (mode == null)
	throw new NoSuchAlgorithmException("null mode");

	String modeUpperCase = mode.toUpperCase(Locale.ENGLISH);

	if (modeUpperCase.equals("ECB")) {
	return;
	}

	SymmetricCipher rawImpl = cipher.getEmbeddedCipher();
	if (modeUpperCase.equals("CBC")) {
	cipherMode = CBC_MODE;
	cipher = new CipherBlockChaining(rawImpl);
	} else if (modeUpperCase.equals("CTS")) {
	cipherMode = CTS_MODE;
	cipher = new CipherTextStealing(rawImpl);
	minBytes = blockSize+1;
	padding = null;
	} else if (modeUpperCase.equals("CTR")) {
	cipherMode = CTR_MODE;
	cipher = new CounterMode(rawImpl);
	unitBytes = 1;
	padding = null;
	} else if (modeUpperCase.startsWith("CFB")) {
	cipherMode = CFB_MODE;
	unitBytes = getNumOfUnit(mode, "CFB".length(), blockSize);
	cipher = new CipherFeedback(rawImpl, unitBytes);
	} else if (modeUpperCase.startsWith("OFB")) {
	cipherMode = OFB_MODE;
	unitBytes = getNumOfUnit(mode, "OFB".length(), blockSize);
	cipher = new OutputFeedback(rawImpl, unitBytes);
	} else if (modeUpperCase.equals("PCBC")) {
	cipherMode = PCBC_MODE;
	cipher = new PCBC(rawImpl);
	}
	else {
	throw new NoSuchAlgorithmException("Cipher mode: " + mode
	+ " not found");
	}
	}

	private static int getNumOfUnit(String mode, int offset, int blockSize)
	throws NoSuchAlgorithmException {
	int result = blockSize; // use blockSize as default value
	if (mode.length() > offset) {
	int numInt;
	try {
	Integer num = Integer.valueOf(mode.substring(offset));
	numInt = num.intValue();
	result = numInt >> 3;
	} catch (NumberFormatException e) {
	throw new NoSuchAlgorithmException
	("Algorithm mode: " + mode + " not implemented");
	}
	if ((numInt % 8 != 0) \|\| (result > blockSize)) {
	throw new NoSuchAlgorithmException
	("Invalid algorithm mode: " + mode);
	}
	}
	return result;
	}

	/**
	* Sets the padding mechanism of this cipher.
	*
	* @param paddingScheme the padding mechanism
	*
	* @exception NoSuchPaddingException if the requested padding mechanism
	* does not exist
	*/
	void setPadding(String paddingScheme)
	throws NoSuchPaddingException
	{
	if (paddingScheme == null) {
	throw new NoSuchPaddingException("null padding");
	}
	if (paddingScheme.equalsIgnoreCase("NoPadding")) {
	padding = null;
	} else if (paddingScheme.equalsIgnoreCase("ISO10126Padding")) {
	padding = new ISO10126Padding(blockSize);
	} else if (paddingScheme.equalsIgnoreCase("PKCS5Padding")) {
	padding = new PKCS5Padding(blockSize);
	} else {
	throw new NoSuchPaddingException("Padding: " + paddingScheme
	+ " not implemented");
	}
	if ((padding != null) &&
	((cipherMode == CTR_MODE) \|\| (cipherMode == CTS_MODE))) {
	padding = null;
	String modeStr = null;
	switch (cipherMode) {
	case CTR_MODE:
	modeStr = "CTR";
	break;
	case CTS_MODE:
	modeStr = "CTS";
	break;
	default:
	// should never happen
	}
	if (modeStr != null) {
	throw new NoSuchPaddingException
	(modeStr + " mode must be used with NoPadding");
	}
	}
	}

	/**
	* Returns the length in bytes that an output buffer would need to be in
	* order to hold the result of the next <code>update</code> or
	* <code>doFinal</code> operation, given the input length
	* <code>inputLen</code> (in bytes).
	*
	* <p>This call takes into account any unprocessed (buffered) data from a
	* previous <code>update</code> call, and padding.
	*
	* <p>The actual output length of the next <code>update</code> or
	* <code>doFinal</code> call may be smaller than the length returned by
	* this method.
	*
	* @param inputLen the input length (in bytes)
	*
	* @return the required output buffer size (in bytes)
	*/
	int getOutputSize(int inputLen) {
	// estimate based on the maximum
	return getOutputSizeByOperation(inputLen, true);
	}

	private int getOutputSizeByOperation(int inputLen, boolean isDoFinal) {
	int totalLen = buffered;
	totalLen = Math.addExact(totalLen, inputLen);
	if (padding != null && !decrypting) {
	if (unitBytes != blockSize) {
	if (totalLen < diffBlocksize) {
	totalLen = diffBlocksize;
	} else {
	int residue = (totalLen - diffBlocksize) % blockSize;
	totalLen = Math.addExact(totalLen, (blockSize - residue));
	}
	} else {
	totalLen = Math.addExact(totalLen, padding.padLength(totalLen));
	}
	}
	return totalLen;
	}

	/**
	* Returns the initialization vector (IV) in a new buffer.
	*
	* <p>This is useful in the case where a random IV has been created
	* (see <a href = "#init">init</a>),
	* or in the context of password-based encryption or
	* decryption, where the IV is derived from a user-provided password.
	*
	* @return the initialization vector in a new buffer, or null if the
	* underlying algorithm does not use an IV, or if the IV has not yet
	* been set.
	*/
	byte[] getIV() {
	byte[] iv = cipher.getIV();
	return (iv == null) ? null : iv.clone();
	}

	/**
	* Returns the parameters used with this cipher.
	*
	* <p>The returned parameters may be the same that were used to initialize
	* this cipher, or may contain the default set of parameters or a set of
	* randomly generated parameters used by the underlying cipher
	* implementation (provided that the underlying cipher implementation
	* uses a default set of parameters or creates new parameters if it needs
	* parameters but was not initialized with any).
	*
	* @return the parameters used with this cipher, or null if this cipher
	* does not use any parameters.
	*/
	AlgorithmParameters getParameters(String algName) {
	if (cipherMode == ECB_MODE) {
	return null;
	}
	AlgorithmParameters params = null;
	AlgorithmParameterSpec spec;
	byte[] iv = getIV();
	if (iv == null) {
	iv = new byte[blockSize];
	SunJCE.getRandom().nextBytes(iv);
	}
	if (algName.equals("RC2")) {
	RC2Crypt rawImpl = (RC2Crypt) cipher.getEmbeddedCipher();
	spec = new RC2ParameterSpec
	(rawImpl.getEffectiveKeyBits(), iv);
	} else {
	spec = new IvParameterSpec(iv);
	}
	try {
	params = AlgorithmParameters.getInstance(algName,
	SunJCE.getInstance());
	params.init(spec);
	} catch (NoSuchAlgorithmException nsae) {
	// should never happen
	throw new RuntimeException("Cannot find " + algName +
	" AlgorithmParameters implementation in SunJCE provider");
	} catch (InvalidParameterSpecException ipse) {
	// should never happen
	throw new RuntimeException(spec.getClass() + " not supported");
	}
	return params;
	}

	/**
	* Initializes this cipher with a key and a source of randomness.
	*
	* <p>The cipher is initialized for one of the following four operations:
	* encryption, decryption, key wrapping or key unwrapping, depending on
	* the value of <code>opmode</code>.
	*
	* <p>If this cipher requires an initialization vector (IV), it will get
	* it from <code>random</code>.
	* This behaviour should only be used in encryption or key wrapping
	* mode, however.
	* When initializing a cipher that requires an IV for decryption or
	* key unwrapping, the IV
	* (same IV that was used for encryption or key wrapping) must be provided
	* explicitly as a
	* parameter, in order to get the correct result.
	*
	* <p>This method also cleans existing buffer and other related state
	* information.
	*
	* @param opmode the operation mode of this cipher (this is one of
	* the following:
	* <code>ENCRYPT_MODE</code>, <code>DECRYPT_MODE</code>,
	* <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>)
	* @param key the secret key
	* @param random the source of randomness
	*
	* @exception InvalidKeyException if the given key is inappropriate for
	* initializing this cipher
	*/
	void init(int opmode, Key key, SecureRandom random)
	throws InvalidKeyException {
	try {
	init(opmode, key, (AlgorithmParameterSpec)null, random);
	} catch (InvalidAlgorithmParameterException e) {
	throw new InvalidKeyException(e.getMessage());
	}
	}

	/**
	* Initializes this cipher with a key, a set of
	* algorithm parameters, and a source of randomness.
	*
	* <p>The cipher is initialized for one of the following four operations:
	* encryption, decryption, key wrapping or key unwrapping, depending on
	* the value of <code>opmode</code>.
	*
	* <p>If this cipher (including its underlying feedback or padding scheme)
	* requires any random bytes, it will get them from <code>random</code>.
	*
	* @param opmode the operation mode of this cipher (this is one of
	* the following:
	* <code>ENCRYPT_MODE</code>, <code>DECRYPT_MODE</code>,
	* <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>)
	* @param key the encryption key
	* @param params the algorithm parameters
	* @param random the source of randomness
	*
	* @exception InvalidKeyException if the given key is inappropriate for
	* initializing this cipher
	* @exception InvalidAlgorithmParameterException if the given algorithm
	* parameters are inappropriate for this cipher
	*/
	void init(int opmode, Key key, AlgorithmParameterSpec params,
	SecureRandom random)
	throws InvalidKeyException, InvalidAlgorithmParameterException {
	decrypting = (opmode == Cipher.DECRYPT_MODE)
	\|\| (opmode == Cipher.UNWRAP_MODE);

	byte[] keyBytes = getKeyBytes(key);
	byte[] ivBytes = null;
	try {
	if (params != null) {
	if (params instanceof IvParameterSpec) {
	ivBytes = ((IvParameterSpec) params).getIV();
	if ((ivBytes == null) \|\| (ivBytes.length != blockSize)) {
	throw new InvalidAlgorithmParameterException
	("Wrong IV length: must be " + blockSize +
	" bytes long");
	}
	} else if (params instanceof RC2ParameterSpec) {
	ivBytes = ((RC2ParameterSpec) params).getIV();
	if ((ivBytes != null) && (ivBytes.length != blockSize)) {
	throw new InvalidAlgorithmParameterException
	("Wrong IV length: must be " + blockSize +
	" bytes long");
	}
	} else {
	throw new InvalidAlgorithmParameterException
	("Unsupported parameter: " + params);
	}
	}
	if (cipherMode == ECB_MODE) {
	if (ivBytes != null) {
	throw new InvalidAlgorithmParameterException
	("ECB mode cannot use IV");
	}
	} else if (ivBytes == null) {
	if (decrypting) {
	throw new InvalidAlgorithmParameterException("Parameters "
	+ "missing");
	}

	if (random == null) {
	random = SunJCE.getRandom();
	}

	ivBytes = new byte[blockSize];
	random.nextBytes(ivBytes);
	}

	buffered = 0;
	diffBlocksize = blockSize;

	String algorithm = key.getAlgorithm();
	cipher.init(decrypting, algorithm, keyBytes, ivBytes);
	} finally {
	Arrays.fill(keyBytes, (byte)0);
	}
	}

	void init(int opmode, Key key, AlgorithmParameters params,
	SecureRandom random)
	throws InvalidKeyException, InvalidAlgorithmParameterException {
	AlgorithmParameterSpec spec = null;
	String paramType = null;
	if (params != null) {
	try {
	// NOTE: RC2 parameters are always handled through
	// init(..., AlgorithmParameterSpec,...) method, so
	// we can assume IvParameterSpec type here.
	paramType = "IV";
	spec = params.getParameterSpec(IvParameterSpec.class);
	} catch (InvalidParameterSpecException ipse) {
	throw new InvalidAlgorithmParameterException
	("Wrong parameter type: " + paramType + " expected");
	}
	}
	init(opmode, key, spec, random);
	}

	/**
	* Return the key bytes of the specified key. Throw an InvalidKeyException
	* if the key is not usable.
	*/
	static byte[] getKeyBytes(Key key) throws InvalidKeyException {
	if (key == null) {
	throw new InvalidKeyException("No key given");
	}
	// note: key.getFormat() may return null
	if (!"RAW".equalsIgnoreCase(key.getFormat())) {
	throw new InvalidKeyException("Wrong format: RAW bytes needed");
	}
	byte[] keyBytes = key.getEncoded();
	if (keyBytes == null) {
	throw new InvalidKeyException("RAW key bytes missing");
	}
	return keyBytes;
	}


	/**
	* Continues a multiple-part encryption or decryption operation
	* (depending on how this cipher was initialized), processing another data
	* part.
	*
	* <p>The first <code>inputLen</code> bytes in the <code>input</code>
	* buffer, starting at <code>inputOffset</code>, are processed, and the
	* result is stored in a new buffer.
	*
	* @param input the input buffer
	* @param inputOffset the offset in <code>input</code> where the input
	* starts
	* @param inputLen the input length
	*
	* @return the new buffer with the result
	*
	* @exception IllegalStateException if this cipher is in a wrong state
	* (e.g., has not been initialized)
	*/
	byte[] update(byte[] input, int inputOffset, int inputLen) {

	byte[] output = null;
	try {
	output = new byte[getOutputSizeByOperation(inputLen, false)];
	int len = update(input, inputOffset, inputLen, output,
	0);
	if (len == output.length) {
	return output;
	} else {
	byte[] copy = Arrays.copyOf(output, len);
	if (decrypting) {
	// Zero out internal buffer which is no longer required
	Arrays.fill(output, (byte) 0x00);
	}
	return copy;
	}
	} catch (ShortBufferException e) {
	// should never happen
	throw new ProviderException("Unexpected exception", e);
	}
	}

	/**
	* Continues a multiple-part encryption or decryption operation
	* (depending on how this cipher was initialized), processing another data
	* part.
	*
	* <p>The first <code>inputLen</code> bytes in the <code>input</code>
	* buffer, starting at <code>inputOffset</code>, are processed, and the
	* result is stored in the <code>output</code> buffer, starting at
	* <code>outputOffset</code>.
	*
	* @param input the input buffer
	* @param inputOffset the offset in <code>input</code> where the input
	* starts
	* @param inputLen the input length
	* @param output the buffer for the result
	* @param outputOffset the offset in <code>output</code> where the result
	* is stored
	*
	* @return the number of bytes stored in <code>output</code>
	*
	* @exception ShortBufferException if the given output buffer is too small
	* to hold the result
	*/
	int update(byte[] input, int inputOffset, int inputLen, byte[] output,
	int outputOffset) throws ShortBufferException {

	// figure out how much can be sent to crypto function
	int len = Math.addExact(buffered, inputLen);
	len -= minBytes;
	if (padding != null && decrypting) {
	// do not include the padding bytes when decrypting
	len -= blockSize;
	}
	// do not count the trailing bytes which do not make up a unit
	len = (len > 0 ? (len - (len % unitBytes)) : 0);

	// check output buffer capacity
	if (output == null \|\| (output.length - outputOffset) < len) {
	throw new ShortBufferException("Output buffer must be "
	+ "(at least) " + len
	+ " bytes long");
	}

	int outLen = 0;
	if (len != 0) { // there is some work to do
	if ((input == output)
	&& (outputOffset - inputOffset < inputLen)
	&& (inputOffset - outputOffset < buffer.length)) {
	// copy 'input' out to avoid its content being
	// overwritten prematurely.
	input = Arrays.copyOfRange(input, inputOffset,
	Math.addExact(inputOffset, inputLen));
	inputOffset = 0;
	}
	if (len <= buffered) {
	// all to-be-processed data are from 'buffer'
	if (decrypting) {
	outLen = cipher.decrypt(buffer, 0, len, output, outputOffset);
	} else {
	outLen = cipher.encrypt(buffer, 0, len, output, outputOffset);
	}
	buffered -= len;
	if (buffered != 0) {
	System.arraycopy(buffer, len, buffer, 0, buffered);
	}
	} else { // len > buffered
	int inputConsumed = len - buffered;
	int temp;
	if (buffered > 0) {
	int bufferCapacity = buffer.length - buffered;
	if (bufferCapacity != 0) {
	temp = Math.min(bufferCapacity, inputConsumed);
	if (unitBytes != blockSize) {
	temp -= (Math.addExact(buffered, temp) % unitBytes);
	}
	System.arraycopy(input, inputOffset, buffer, buffered, temp);
	inputOffset = Math.addExact(inputOffset, temp);
	inputConsumed -= temp;
	inputLen -= temp;
	buffered = Math.addExact(buffered, temp);
	}
	// process 'buffer'. When finished we can null out 'buffer'
	// Only necessary to null out if buffer holds data for encryption
	if (decrypting) {
	outLen = cipher.decrypt(buffer, 0, buffered, output, outputOffset);
	} else {
	outLen = cipher.encrypt(buffer, 0, buffered, output, outputOffset);
	//encrypt mode. Zero out internal (input) buffer
	Arrays.fill(buffer, (byte) 0x00);
	}
	outputOffset = Math.addExact(outputOffset, outLen);
	buffered = 0;
	}
	if (inputConsumed > 0) { // still has input to process
	if (decrypting) {
	outLen += cipher.decrypt(input, inputOffset, inputConsumed,
	output, outputOffset);
	} else {
	outLen += cipher.encrypt(input, inputOffset, inputConsumed,
	output, outputOffset);
	}
	inputOffset += inputConsumed;
	inputLen -= inputConsumed;
	}
	}
	// Let's keep track of how many bytes are needed to make
	// the total input length a multiple of blocksize when
	// padding is applied
	if (unitBytes != blockSize) {
	if (len < diffBlocksize) {
	diffBlocksize -= len;
	} else {
	diffBlocksize = blockSize -
	((len - diffBlocksize) % blockSize);
	}
	}
	}
	// Store remaining input into 'buffer' again
	if (inputLen > 0) {
	System.arraycopy(input, inputOffset, buffer, buffered,
	inputLen);
	buffered = Math.addExact(buffered, inputLen);
	}
	return outLen;
	}

	/**
	* Encrypts or decrypts data in a single-part operation,
	* or finishes a multiple-part operation.
	* The data is encrypted or decrypted, depending on how this cipher was
	* initialized.
	*
	* <p>The first <code>inputLen</code> bytes in the <code>input</code>
	* buffer, starting at <code>inputOffset</code>, and any input bytes that
	* may have been buffered during a previous <code>update</code> operation,
	* are processed, with padding (if requested) being applied.
	* The result is stored in a new buffer.
	*
	* <p>The cipher is reset to its initial state (uninitialized) after this
	* call.
	*
	* @param input the input buffer
	* @param inputOffset the offset in <code>input</code> where the input
	* starts
	* @param inputLen the input length
	*
	* @return the new buffer with the result
	*
	* @exception IllegalBlockSizeException if this cipher is a block cipher,
	* no padding has been requested (only in encryption mode), and the total
	* input length of the data processed by this cipher is not a multiple of
	* block size
	* @exception BadPaddingException if this cipher is in decryption mode,
	* and (un)padding has been requested, but the decrypted data is not
	* bounded by the appropriate padding bytes
	*/
	byte[] doFinal(byte[] input, int inputOffset, int inputLen)
	throws IllegalBlockSizeException, BadPaddingException {
	try {
	byte[] output = new byte[getOutputSizeByOperation(inputLen, true)];
	byte[] finalBuf = prepareInputBuffer(input, inputOffset,
	inputLen, output, 0);
	int finalOffset = (finalBuf == input) ? inputOffset : 0;
	int finalBufLen = (finalBuf == input) ? inputLen : finalBuf.length;

	int outLen = fillOutputBuffer(finalBuf, finalOffset, output, 0,
	finalBufLen, input);

	endDoFinal();
	if (outLen < output.length) {
	byte[] copy = Arrays.copyOf(output, outLen);
	if (decrypting) {
	// Zero out internal (output) array
	Arrays.fill(output, (byte) 0x00);
	}
	return copy;
	} else {
	return output;
	}
	} catch (ShortBufferException e) {
	// never thrown
	throw new ProviderException("Unexpected exception", e);
	}
	}

	/**
	* Encrypts or decrypts data in a single-part operation,
	* or finishes a multiple-part operation.
	* The data is encrypted or decrypted, depending on how this cipher was
	* initialized.
	*
	* <p>The first <code>inputLen</code> bytes in the <code>input</code>
	* buffer, starting at <code>inputOffset</code>, and any input bytes that
	* may have been buffered during a previous <code>update</code> operation,
	* are processed, with padding (if requested) being applied.
	* The result is stored in the <code>output</code> buffer, starting at
	* <code>outputOffset</code>.
	*
	* <p>The cipher is reset to its initial state (uninitialized) after this
	* call.
	*
	* @param input the input buffer
	* @param inputOffset the offset in <code>input</code> where the input
	* starts
	* @param inputLen the input length
	* @param output the buffer for the result
	* @param outputOffset the offset in <code>output</code> where the result
	* is stored
	*
	* @return the number of bytes stored in <code>output</code>
	*
	* @exception IllegalBlockSizeException if this cipher is a block cipher,
	* no padding has been requested (only in encryption mode), and the total
	* input length of the data processed by this cipher is not a multiple of
	* block size
	* @exception ShortBufferException if the given output buffer is too small
	* to hold the result
	* @exception BadPaddingException if this cipher is in decryption mode,
	* and (un)padding has been requested, but the decrypted data is not
	* bounded by the appropriate padding bytes
	*/
	int doFinal(byte[] input, int inputOffset, int inputLen, byte[] output,
	int outputOffset)
	throws IllegalBlockSizeException, ShortBufferException,
	BadPaddingException {

	int estOutSize = getOutputSizeByOperation(inputLen, true);
	int outputCapacity = checkOutputCapacity(output, outputOffset,
	estOutSize);
	int offset = outputOffset;
	byte[] finalBuf = prepareInputBuffer(input, inputOffset,
	inputLen, output, outputOffset);
	byte[] internalOutput = null; // for decrypting only

	int finalOffset = (finalBuf == input) ? inputOffset : 0;
	int finalBufLen = (finalBuf == input) ? inputLen : finalBuf.length;

	if (decrypting) {
	// if the size of specified output buffer is less than
	// the length of the cipher text, then the current
	// content of cipher has to be preserved in order for
	// users to retry the call with a larger buffer in the
	// case of ShortBufferException.
	if (outputCapacity < estOutSize) {
	cipher.save();
	}
	// create temporary output buffer if the estimated size is larger
	// than the user-provided buffer.
	internalOutput = new byte[estOutSize];
	offset = 0;
	}

	byte[] outBuffer = (internalOutput != null) ? internalOutput : output;
	int outLen = fillOutputBuffer(finalBuf, finalOffset, outBuffer,
	offset, finalBufLen, input);

	if (decrypting) {

	if (outputCapacity < outLen) {
	// restore so users can retry with a larger buffer
	cipher.restore();
	throw new ShortBufferException("Output buffer too short: "
	+ (outputCapacity) + " bytes given, " + outLen
	+ " bytes needed");
	}
	// copy the result into user-supplied output buffer
	if (internalOutput != null) {
	System.arraycopy(internalOutput, 0, output, outputOffset,
	outLen);
	// decrypt mode. Zero out output data that's not required
	Arrays.fill(internalOutput, (byte) 0x00);
	}
	}
	endDoFinal();
	return outLen;
	}

	private void endDoFinal() {
	buffered = 0;
	diffBlocksize = blockSize;
	if (cipherMode != ECB_MODE) {
	cipher.reset();
	}
	}

	private int unpad(int outLen, int off, byte[] outWithPadding)
	throws BadPaddingException {
	int padStart = padding.unpad(outWithPadding, off, outLen);
	if (padStart < 0) {
	throw new BadPaddingException("Given final block not " +
	"properly padded. Such issues can arise if a bad key " +
	"is used during decryption.");
	}
	return padStart - off;
	}

	private byte[] prepareInputBuffer(byte[] input, int inputOffset,
	int inputLen, byte[] output, int outputOffset)
	throws IllegalBlockSizeException, ShortBufferException {
	// calculate total input length
	int len = Math.addExact(buffered, inputLen);
	// calculate padding length
	int totalLen = len;
	int paddingLen = 0;
	// will the total input length be a multiple of blockSize?
	if (unitBytes != blockSize) {
	if (totalLen < diffBlocksize) {
	paddingLen = diffBlocksize - totalLen;
	} else {
	paddingLen = blockSize -
	((totalLen - diffBlocksize) % blockSize);
	}
	} else if (padding != null) {
	paddingLen = padding.padLength(totalLen);
	}

	if (decrypting && (padding != null) &&
	(paddingLen > 0) && (paddingLen != blockSize)) {
	throw new IllegalBlockSizeException
	("Input length must be multiple of " + blockSize +
	" when decrypting with padded cipher");
	}

	/*
	* prepare the final input, assemble a new buffer if any
	* of the following is true:
	* - 'input' and 'output' are the same buffer
	* - there are internally buffered bytes
	* - doing encryption and padding is needed
	*/
	if ((buffered != 0) \|\| (!decrypting && padding != null) \|\|
	((input == output)
	&& (outputOffset - inputOffset < inputLen)
	&& (inputOffset - outputOffset < buffer.length))) {
	byte[] finalBuf;
	if (decrypting \|\| padding == null) {
	paddingLen = 0;
	}
	finalBuf = new byte[Math.addExact(len, paddingLen)];
	if (buffered != 0) {
	System.arraycopy(buffer, 0, finalBuf, 0, buffered);
	if (!decrypting) {
	// done with input buffer. We should zero out the
	// data if we're in encrypt mode.
	Arrays.fill(buffer, (byte) 0x00);
	}
	}
	if (inputLen != 0) {
	System.arraycopy(input, inputOffset, finalBuf,
	buffered, inputLen);
	}
	if (paddingLen != 0) {
	padding.padWithLen(finalBuf, Math.addExact(buffered, inputLen), paddingLen);
	}
	return finalBuf;
	}
	return input;
	}

	private int fillOutputBuffer(byte[] finalBuf, int finalOffset,
	byte[] output, int outOfs, int finalBufLen, byte[] input)
	throws ShortBufferException, BadPaddingException,
	IllegalBlockSizeException {

	int len;
	try {
	len = finalNoPadding(finalBuf, finalOffset, output,
	outOfs, finalBufLen);
	if (decrypting && padding != null) {
	len = unpad(len, outOfs, output);
	}
	return len;
	} finally {
	if (!decrypting && finalBuf != input) {
	// done with internal finalBuf array. Copied to output
	Arrays.fill(finalBuf, (byte) 0x00);
	}
	}
	}


	private int checkOutputCapacity(byte[] output, int outputOffset,
	int estOutSize) throws ShortBufferException {
	// check output buffer capacity.
	// if we are decrypting with padding applied, we can perform this
	// check only after we have determined how many padding bytes there
	// are.
	int outputCapacity = output.length - outputOffset;
	int minOutSize = decrypting ? (estOutSize - blockSize) : estOutSize;
	if ((output == null) \|\| (outputCapacity < minOutSize)) {
	throw new ShortBufferException("Output buffer must be "
	+ "(at least) " + minOutSize + " bytes long");
	}
	return outputCapacity;
	}

	private int finalNoPadding(byte[] in, int inOfs, byte[] out, int outOfs,
	int len)
	throws IllegalBlockSizeException, ShortBufferException {

	if (in == null \|\| len == 0) {
	return 0;
	}
	if ((cipherMode != CFB_MODE) && (cipherMode != OFB_MODE) &&
	((len % unitBytes) != 0) && (cipherMode != CTS_MODE)) {
	if (padding != null) {
	throw new IllegalBlockSizeException
	("Input length (with padding) not multiple of " +
	unitBytes + " bytes");
	} else {
	throw new IllegalBlockSizeException
	("Input length not multiple of " + unitBytes
	+ " bytes");
	}
	}
	int outLen;
	if (decrypting) {
	outLen = cipher.decryptFinal(in, inOfs, len, out, outOfs);
	} else {
	outLen = cipher.encryptFinal(in, inOfs, len, out, outOfs);
	}
	return outLen;
	}

	// Note: Wrap() and Unwrap() are the same in
	// each of SunJCE CipherSpi implementation classes.
	// They are duplicated due to export control requirements:
	// All CipherSpi implementation must be final.
	/**
	* Wrap a key.
	*
	* @param key the key to be wrapped.
	*
	* @return the wrapped key.
	*
	* @exception IllegalBlockSizeException if this cipher is a block
	* cipher, no padding has been requested, and the length of the
	* encoding of the key to be wrapped is not a
	* multiple of the block size.
	*
	* @exception InvalidKeyException if it is impossible or unsafe to
	* wrap the key with this cipher (e.g., a hardware protected key is
	* being passed to a software only cipher).
	*/
	byte[] wrap(Key key)
	throws IllegalBlockSizeException, InvalidKeyException {
	byte[] result = null;

	try {
	byte[] encodedKey = key.getEncoded();
	if ((encodedKey == null) \|\| (encodedKey.length == 0)) {
	throw new InvalidKeyException("Cannot get an encoding of " +
	"the key to be wrapped");
	}
	try {
	result = doFinal(encodedKey, 0, encodedKey.length);
	} finally {
	Arrays.fill(encodedKey, (byte)0);
	}
	} catch (BadPaddingException e) {
	// Should never happen
	}
	return result;
	}

	/**
	* Unwrap a previously wrapped key.
	*
	* @param wrappedKey the key to be unwrapped.
	*
	* @param wrappedKeyAlgorithm the algorithm the wrapped key is for.
	*
	* @param wrappedKeyType the type of the wrapped key.
	* This is one of <code>Cipher.SECRET_KEY</code>,
	* <code>Cipher.PRIVATE_KEY</code>, or <code>Cipher.PUBLIC_KEY</code>.
	*
	* @return the unwrapped key.
	*
	* @exception NoSuchAlgorithmException if no installed providers
	* can create keys of type <code>wrappedKeyType</code> for the
	* <code>wrappedKeyAlgorithm</code>.
	*
	* @exception InvalidKeyException if <code>wrappedKey</code> does not
	* represent a wrapped key of type <code>wrappedKeyType</code> for
	* the <code>wrappedKeyAlgorithm</code>.
	*/
	Key unwrap(byte[] wrappedKey, String wrappedKeyAlgorithm,
	int wrappedKeyType)
	throws InvalidKeyException, NoSuchAlgorithmException {
	byte[] encodedKey;
	try {
	encodedKey = doFinal(wrappedKey, 0, wrappedKey.length);
	} catch (BadPaddingException ePadding) {
	throw new InvalidKeyException("The wrapped key is not padded " +
	"correctly");
	} catch (IllegalBlockSizeException eBlockSize) {
	throw new InvalidKeyException("The wrapped key does not have " +
	"the correct length");
	}
	try {
	return ConstructKeys.constructKey(encodedKey, wrappedKeyAlgorithm,
	wrappedKeyType);
	} finally {
	Arrays.fill(encodedKey, (byte)0);
	}
	}
	}

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