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	/*
	* Copyright (c) 2002, 2012, 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.nio.ByteBuffer;

	import javax.crypto.MacSpi;
	import javax.crypto.SecretKey;
	import java.security.*;
	import java.security.spec.*;

	/**
	* This class constitutes the core of HMAC-<MD> algorithms, where
	* <MD> can be SHA1 or MD5, etc. See RFC 2104 for spec.
	*
	* It also contains the implementation classes for SHA-224, SHA-256,
	* SHA-384, and SHA-512 HMACs.
	*
	* @author Jan Luehe
	*/
	abstract class HmacCore extends MacSpi implements Cloneable {

	private MessageDigest md;
	private byte[] k_ipad; // inner padding - key XORd with ipad
	private byte[] k_opad; // outer padding - key XORd with opad
	private boolean first; // Is this the first data to be processed?

	private final int blockLen;

	/**
	* Standard constructor, creates a new HmacCore instance using the
	* specified MessageDigest object.
	*/
	HmacCore(MessageDigest md, int bl) {
	this.md = md;
	this.blockLen = bl;
	this.k_ipad = new byte[blockLen];
	this.k_opad = new byte[blockLen];
	first = true;
	}

	/**
	* Standard constructor, creates a new HmacCore instance instantiating
	* a MessageDigest of the specified name.
	*/
	HmacCore(String digestAlgorithm, int bl) throws NoSuchAlgorithmException {
	this(MessageDigest.getInstance(digestAlgorithm), bl);
	}

	/**
	* Returns the length of the HMAC in bytes.
	*
	* @return the HMAC length in bytes.
	*/
	protected int engineGetMacLength() {
	return this.md.getDigestLength();
	}

	/**
	* Initializes the HMAC with the given secret key and algorithm parameters.
	*
	* @param key the secret key.
	* @param params the algorithm parameters.
	*
	* @exception InvalidKeyException if the given key is inappropriate for
	* initializing this MAC.
	* @exception InvalidAlgorithmParameterException if the given algorithm
	* parameters are inappropriate for this MAC.
	*/
	protected void engineInit(Key key, AlgorithmParameterSpec params)
	throws InvalidKeyException, InvalidAlgorithmParameterException {
	if (params != null) {
	throw new InvalidAlgorithmParameterException
	("HMAC does not use parameters");
	}

	if (!(key instanceof SecretKey)) {
	throw new InvalidKeyException("Secret key expected");
	}

	byte[] secret = key.getEncoded();
	if (secret == null) {
	throw new InvalidKeyException("Missing key data");
	}

	// if key is longer than the block length, reset it using
	// the message digest object.
	if (secret.length > blockLen) {
	byte[] tmp = md.digest(secret);
	// now erase the secret
	Arrays.fill(secret, (byte)0);
	secret = tmp;
	}

	// XOR k with ipad and opad, respectively
	for (int i = 0; i < blockLen; i++) {
	int si = (i < secret.length) ? secret[i] : 0;
	k_ipad[i] = (byte)(si ^ 0x36);
	k_opad[i] = (byte)(si ^ 0x5c);
	}

	// now erase the secret
	Arrays.fill(secret, (byte)0);
	secret = null;

	engineReset();
	}

	/**
	* Processes the given byte.
	*
	* @param input the input byte to be processed.
	*/
	protected void engineUpdate(byte input) {
	if (first == true) {
	// compute digest for 1st pass; start with inner pad
	md.update(k_ipad);
	first = false;
	}

	// add the passed byte to the inner digest
	md.update(input);
	}

	/**
	* Processes the first <code>len</code> bytes in <code>input</code>,
	* starting at <code>offset</code>.
	*
	* @param input the input buffer.
	* @param offset the offset in <code>input</code> where the input starts.
	* @param len the number of bytes to process.
	*/
	protected void engineUpdate(byte input[], int offset, int len) {
	if (first == true) {
	// compute digest for 1st pass; start with inner pad
	md.update(k_ipad);
	first = false;
	}

	// add the selected part of an array of bytes to the inner digest
	md.update(input, offset, len);
	}

	/**
	* Processes the <code>input.remaining()</code> bytes in the ByteBuffer
	* <code>input</code>.
	*
	* @param input the input byte buffer.
	*/
	protected void engineUpdate(ByteBuffer input) {
	if (first == true) {
	// compute digest for 1st pass; start with inner pad
	md.update(k_ipad);
	first = false;
	}

	md.update(input);
	}

	/**
	* Completes the HMAC computation and resets the HMAC for further use,
	* maintaining the secret key that the HMAC was initialized with.
	*
	* @return the HMAC result.
	*/
	protected byte[] engineDoFinal() {
	if (first == true) {
	// compute digest for 1st pass; start with inner pad
	md.update(k_ipad);
	} else {
	first = true;
	}

	try {
	// finish the inner digest
	byte[] tmp = md.digest();

	// compute digest for 2nd pass; start with outer pad
	md.update(k_opad);
	// add result of 1st hash
	md.update(tmp);

	md.digest(tmp, 0, tmp.length);
	return tmp;
	} catch (DigestException e) {
	// should never occur
	throw new ProviderException(e);
	}
	}

	/**
	* Resets the HMAC for further use, maintaining the secret key that the
	* HMAC was initialized with.
	*/
	protected void engineReset() {
	if (first == false) {
	md.reset();
	first = true;
	}
	}

	/*
	* Clones this object.
	*/
	public Object clone() throws CloneNotSupportedException {
	HmacCore copy = (HmacCore) super.clone();
	copy.md = (MessageDigest) md.clone();
	copy.k_ipad = k_ipad.clone();
	copy.k_opad = k_opad.clone();
	return copy;
	}

	// nested static class for the HmacSHA224 implementation
	public static final class HmacSHA224 extends HmacCore {
	public HmacSHA224() throws NoSuchAlgorithmException {
	super("SHA-224", 64);
	}
	}

	// nested static class for the HmacSHA256 implementation
	public static final class HmacSHA256 extends HmacCore {
	public HmacSHA256() throws NoSuchAlgorithmException {
	super("SHA-256", 64);
	}
	}

	// nested static class for the HmacSHA384 implementation
	public static final class HmacSHA384 extends HmacCore {
	public HmacSHA384() throws NoSuchAlgorithmException {
	super("SHA-384", 128);
	}
	}

	// nested static class for the HmacSHA512 implementation
	public static final class HmacSHA512 extends HmacCore {
	public HmacSHA512() throws NoSuchAlgorithmException {
	super("SHA-512", 128);
	}
	}
	}

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