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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 java.security;

	import java.util.*;

	import java.security.spec.AlgorithmParameterSpec;

	import java.security.Provider.Service;

	import sun.security.jca.*;
	import sun.security.jca.GetInstance.Instance;
	import sun.security.util.Debug;

	/**
	* The KeyPairGenerator class is used to generate pairs of
	* public and private keys. Key pair generators are constructed using the
	* {@code getInstance} factory methods (static methods that
	* return instances of a given class).
	*
	* <p>A Key pair generator for a particular algorithm creates a public/private
	* key pair that can be used with this algorithm. It also associates
	* algorithm-specific parameters with each of the generated keys.
	*
	* <p>There are two ways to generate a key pair: in an algorithm-independent
	* manner, and in an algorithm-specific manner.
	* The only difference between the two is the initialization of the object:
	*
	* <ul>
	* <li><b>Algorithm-Independent Initialization</b>
	* <p>All key pair generators share the concepts of a keysize and a
	* source of randomness. The keysize is interpreted differently for different
	* algorithms (e.g., in the case of the <i>DSA</i> algorithm, the keysize
	* corresponds to the length of the modulus).
	* There is an
	* {@link #initialize(int, java.security.SecureRandom) initialize}
	* method in this KeyPairGenerator class that takes these two universally
	* shared types of arguments. There is also one that takes just a
	* {@code keysize} argument, and uses the {@code SecureRandom}
	* implementation of the highest-priority installed provider as the source
	* of randomness. (If none of the installed providers supply an implementation
	* of {@code SecureRandom}, a system-provided source of randomness is
	* used.)
	*
	* <p>Since no other parameters are specified when you call the above
	* algorithm-independent {@code initialize} methods, it is up to the
	* provider what to do about the algorithm-specific parameters (if any) to be
	* associated with each of the keys.
	*
	* <p>If the algorithm is the <i>DSA</i> algorithm, and the keysize (modulus
	* size) is 512, 768, 1024, or 2048, then the <i>Sun</i> provider uses a set of
	* precomputed values for the {@code p}, {@code q}, and
	* {@code g} parameters. If the modulus size is not one of the above
	* values, the <i>Sun</i> provider creates a new set of parameters. Other
	* providers might have precomputed parameter sets for more than just the
	* modulus sizes mentioned above. Still others might not have a list of
	* precomputed parameters at all and instead always create new parameter sets.
	*
	* <li><b>Algorithm-Specific Initialization</b>
	* <p>For situations where a set of algorithm-specific parameters already
	* exists (e.g., so-called <i>community parameters</i> in DSA), there are two
	* {@link #initialize(java.security.spec.AlgorithmParameterSpec)
	* initialize} methods that have an {@code AlgorithmParameterSpec}
	* argument. One also has a {@code SecureRandom} argument, while
	* the other uses the {@code SecureRandom}
	* implementation of the highest-priority installed provider as the source
	* of randomness. (If none of the installed providers supply an implementation
	* of {@code SecureRandom}, a system-provided source of randomness is
	* used.)
	* </ul>
	*
	* <p>In case the client does not explicitly initialize the KeyPairGenerator
	* (via a call to an {@code initialize} method), each provider must
	* supply (and document) a default initialization.
	* See the Keysize Restriction sections of the
	* {@extLink security_guide_jdk_providers JDK Providers}
	* document for information on the KeyPairGenerator defaults used by
	* JDK providers.
	* However, note that defaults may vary across different providers.
	* Additionally, the default value for a provider may change in a future
	* version. Therefore, it is recommended to explicitly initialize the
	* KeyPairGenerator instead of relying on provider-specific defaults.
	*
	* <p>Note that this class is abstract and extends from
	* {@code KeyPairGeneratorSpi} for historical reasons.
	* Application developers should only take notice of the methods defined in
	* this {@code KeyPairGenerator} class; all the methods in
	* the superclass are intended for cryptographic service providers who wish to
	* supply their own implementations of key pair generators.
	*
	* <p> Every implementation of the Java platform is required to support the
	* following standard {@code KeyPairGenerator} algorithms and keysizes in
	* parentheses:
	* <ul>
	* <li>{@code DiffieHellman} (1024, 2048, 4096)</li>
	* <li>{@code DSA} (1024, 2048)</li>
	* <li>{@code RSA} (1024, 2048, 4096)</li>
	* </ul>
	* These algorithms are described in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#keypairgenerator-algorithms">
	* KeyPairGenerator section</a> of the
	* Java Security Standard Algorithm Names Specification.
	* Consult the release documentation for your implementation to see if any
	* other algorithms are supported.
	*
	* @author Benjamin Renaud
	* @since 1.1
	*
	* @see java.security.spec.AlgorithmParameterSpec
	*/

	public abstract class KeyPairGenerator extends KeyPairGeneratorSpi {

	private static final Debug pdebug =
	Debug.getInstance("provider", "Provider");
	private static final boolean skipDebug =
	Debug.isOn("engine=") && !Debug.isOn("keypairgenerator");

	private final String algorithm;

	// The provider
	Provider provider;

	/**
	* Creates a KeyPairGenerator object for the specified algorithm.
	*
	* @param algorithm the standard string name of the algorithm.
	* See the KeyPairGenerator section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#keypairgenerator-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*/
	protected KeyPairGenerator(String algorithm) {
	this.algorithm = algorithm;
	}

	/**
	* Returns the standard name of the algorithm for this key pair generator.
	* See the KeyPairGenerator section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#keypairgenerator-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*
	* @return the standard string name of the algorithm.
	*/
	public String getAlgorithm() {
	return this.algorithm;
	}

	private static KeyPairGenerator getInstance(Instance instance,
	String algorithm) {
	KeyPairGenerator kpg;
	if (instance.impl instanceof KeyPairGenerator) {
	kpg = (KeyPairGenerator)instance.impl;
	} else {
	KeyPairGeneratorSpi spi = (KeyPairGeneratorSpi)instance.impl;
	kpg = new Delegate(spi, algorithm);
	}
	kpg.provider = instance.provider;

	if (!skipDebug && pdebug != null) {
	pdebug.println("KeyPairGenerator." + algorithm +
	" algorithm from: " + kpg.provider.getName());
	}

	return kpg;
	}

	/**
	* Returns a KeyPairGenerator object that generates public/private
	* key pairs for the specified algorithm.
	*
	* <p> This method traverses the list of registered security Providers,
	* starting with the most preferred Provider.
	* A new KeyPairGenerator object encapsulating the
	* KeyPairGeneratorSpi implementation from the first
	* Provider that supports the specified algorithm is returned.
	*
	* <p> Note that the list of registered providers may be retrieved via
	* the {@link Security#getProviders() Security.getProviders()} method.
	*
	* @implNote
	* The JDK Reference Implementation additionally uses the
	* {@code jdk.security.provider.preferred}
	* {@link Security#getProperty(String) Security} property to determine
	* the preferred provider order for the specified algorithm. This
	* may be different than the order of providers returned by
	* {@link Security#getProviders() Security.getProviders()}.
	*
	* @param algorithm the standard string name of the algorithm.
	* See the KeyPairGenerator section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#keypairgenerator-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*
	* @return the new {@code KeyPairGenerator} object
	*
	* @throws NoSuchAlgorithmException if no {@code Provider} supports a
	* {@code KeyPairGeneratorSpi} implementation for the
	* specified algorithm
	*
	* @throws NullPointerException if {@code algorithm} is {@code null}
	*
	* @see Provider
	*/
	public static KeyPairGenerator getInstance(String algorithm)
	throws NoSuchAlgorithmException {
	Objects.requireNonNull(algorithm, "null algorithm name");
	List<Service> list =
	GetInstance.getServices("KeyPairGenerator", algorithm);
	Iterator<Service> t = list.iterator();
	if (t.hasNext() == false) {
	throw new NoSuchAlgorithmException
	(algorithm + " KeyPairGenerator not available");
	}
	// find a working Spi or KeyPairGenerator subclass
	NoSuchAlgorithmException failure = null;
	do {
	Service s = t.next();
	try {
	Instance instance =
	GetInstance.getInstance(s, KeyPairGeneratorSpi.class);
	if (instance.impl instanceof KeyPairGenerator) {
	return getInstance(instance, algorithm);
	} else {
	return new Delegate(instance, t, algorithm);
	}
	} catch (NoSuchAlgorithmException e) {
	if (failure == null) {
	failure = e;
	}
	}
	} while (t.hasNext());
	throw failure;
	}

	/**
	* Returns a KeyPairGenerator object that generates public/private
	* key pairs for the specified algorithm.
	*
	* <p> A new KeyPairGenerator object encapsulating the
	* KeyPairGeneratorSpi implementation from the specified provider
	* is returned. The specified provider must be registered
	* in the security provider list.
	*
	* <p> Note that the list of registered providers may be retrieved via
	* the {@link Security#getProviders() Security.getProviders()} method.
	*
	* @param algorithm the standard string name of the algorithm.
	* See the KeyPairGenerator section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#keypairgenerator-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*
	* @param provider the string name of the provider.
	*
	* @return the new {@code KeyPairGenerator} object
	*
	* @throws IllegalArgumentException if the provider name is {@code null}
	* or empty
	*
	* @throws NoSuchAlgorithmException if a {@code KeyPairGeneratorSpi}
	* implementation for the specified algorithm is not
	* available from the specified provider
	*
	* @throws NoSuchProviderException if the specified provider is not
	* registered in the security provider list
	*
	* @throws NullPointerException if {@code algorithm} is {@code null}
	*
	* @see Provider
	*/
	public static KeyPairGenerator getInstance(String algorithm,
	String provider)
	throws NoSuchAlgorithmException, NoSuchProviderException {
	Objects.requireNonNull(algorithm, "null algorithm name");
	Instance instance = GetInstance.getInstance("KeyPairGenerator",
	KeyPairGeneratorSpi.class, algorithm, provider);
	return getInstance(instance, algorithm);
	}

	/**
	* Returns a KeyPairGenerator object that generates public/private
	* key pairs for the specified algorithm.
	*
	* <p> A new KeyPairGenerator object encapsulating the
	* KeyPairGeneratorSpi implementation from the specified Provider
	* object is returned. Note that the specified Provider object
	* does not have to be registered in the provider list.
	*
	* @param algorithm the standard string name of the algorithm.
	* See the KeyPairGenerator section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#keypairgenerator-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*
	* @param provider the provider.
	*
	* @return the new {@code KeyPairGenerator} object
	*
	* @throws IllegalArgumentException if the specified provider is
	* {@code null}
	*
	* @throws NoSuchAlgorithmException if a {@code KeyPairGeneratorSpi}
	* implementation for the specified algorithm is not available
	* from the specified {@code Provider} object
	*
	* @throws NullPointerException if {@code algorithm} is {@code null}
	*
	* @see Provider
	*
	* @since 1.4
	*/
	public static KeyPairGenerator getInstance(String algorithm,
	Provider provider) throws NoSuchAlgorithmException {
	Objects.requireNonNull(algorithm, "null algorithm name");
	Instance instance = GetInstance.getInstance("KeyPairGenerator",
	KeyPairGeneratorSpi.class, algorithm, provider);
	return getInstance(instance, algorithm);
	}

	/**
	* Returns the provider of this key pair generator object.
	*
	* @return the provider of this key pair generator object
	*/
	public final Provider getProvider() {
	disableFailover();
	return this.provider;
	}

	void disableFailover() {
	// empty, overridden in Delegate
	}

	/**
	* Initializes the key pair generator for a certain keysize using
	* a default parameter set and the {@code SecureRandom}
	* implementation of the highest-priority installed provider as the source
	* of randomness.
	* (If none of the installed providers supply an implementation of
	* {@code SecureRandom}, a system-provided source of randomness is
	* used.)
	*
	* @param keysize the keysize. This is an
	* algorithm-specific metric, such as modulus length, specified in
	* number of bits.
	*
	* @exception InvalidParameterException if the {@code keysize} is not
	* supported by this KeyPairGenerator object.
	*/
	public void initialize(int keysize) {
	initialize(keysize, JCAUtil.getSecureRandom());
	}

	/**
	* Initializes the key pair generator for a certain keysize with
	* the given source of randomness (and a default parameter set).
	*
	* @param keysize the keysize. This is an
	* algorithm-specific metric, such as modulus length, specified in
	* number of bits.
	* @param random the source of randomness.
	*
	* @exception InvalidParameterException if the {@code keysize} is not
	* supported by this KeyPairGenerator object.
	*
	* @since 1.2
	*/
	public void initialize(int keysize, SecureRandom random) {
	// This does nothing, because either
	// 1. the implementation object returned by getInstance() is an
	// instance of KeyPairGenerator which has its own
	// initialize(keysize, random) method, so the application would
	// be calling that method directly, or
	// 2. the implementation returned by getInstance() is an instance
	// of Delegate, in which case initialize(keysize, random) is
	// overridden to call the corresponding SPI method.
	// (This is a special case, because the API and SPI method have the
	// same name.)
	}

	/**
	* Initializes the key pair generator using the specified parameter
	* set and the {@code SecureRandom}
	* implementation of the highest-priority installed provider as the source
	* of randomness.
	* (If none of the installed providers supply an implementation of
	* {@code SecureRandom}, a system-provided source of randomness is
	* used.)
	*
	* <p>This concrete method has been added to this previously-defined
	* abstract class.
	* This method calls the KeyPairGeneratorSpi
	* {@link KeyPairGeneratorSpi#initialize(
	* java.security.spec.AlgorithmParameterSpec,
	* java.security.SecureRandom) initialize} method,
	* passing it {@code params} and a source of randomness (obtained
	* from the highest-priority installed provider or system-provided if none
	* of the installed providers supply one).
	* That {@code initialize} method always throws an
	* UnsupportedOperationException if it is not overridden by the provider.
	*
	* @param params the parameter set used to generate the keys.
	*
	* @exception InvalidAlgorithmParameterException if the given parameters
	* are inappropriate for this key pair generator.
	*
	* @since 1.2
	*/
	public void initialize(AlgorithmParameterSpec params)
	throws InvalidAlgorithmParameterException {
	initialize(params, JCAUtil.getSecureRandom());
	}

	/**
	* Initializes the key pair generator with the given parameter
	* set and source of randomness.
	*
	* <p>This concrete method has been added to this previously-defined
	* abstract class.
	* This method calls the KeyPairGeneratorSpi {@link
	* KeyPairGeneratorSpi#initialize(
	* java.security.spec.AlgorithmParameterSpec,
	* java.security.SecureRandom) initialize} method,
	* passing it {@code params} and {@code random}.
	* That {@code initialize}
	* method always throws an
	* UnsupportedOperationException if it is not overridden by the provider.
	*
	* @param params the parameter set used to generate the keys.
	* @param random the source of randomness.
	*
	* @exception InvalidAlgorithmParameterException if the given parameters
	* are inappropriate for this key pair generator.
	*
	* @since 1.2
	*/
	public void initialize(AlgorithmParameterSpec params,
	SecureRandom random)
	throws InvalidAlgorithmParameterException
	{
	// This does nothing, because either
	// 1. the implementation object returned by getInstance() is an
	// instance of KeyPairGenerator which has its own
	// initialize(params, random) method, so the application would
	// be calling that method directly, or
	// 2. the implementation returned by getInstance() is an instance
	// of Delegate, in which case initialize(params, random) is
	// overridden to call the corresponding SPI method.
	// (This is a special case, because the API and SPI method have the
	// same name.)
	}

	/**
	* Generates a key pair.
	*
	* <p>If this KeyPairGenerator has not been initialized explicitly,
	* provider-specific defaults will be used for the size and other
	* (algorithm-specific) values of the generated keys.
	*
	* <p>This will generate a new key pair every time it is called.
	*
	* <p>This method is functionally equivalent to
	* {@link #generateKeyPair() generateKeyPair}.
	*
	* @return the generated key pair
	*
	* @since 1.2
	*/
	public final KeyPair genKeyPair() {
	return generateKeyPair();
	}

	/**
	* Generates a key pair.
	*
	* <p>If this KeyPairGenerator has not been initialized explicitly,
	* provider-specific defaults will be used for the size and other
	* (algorithm-specific) values of the generated keys.
	*
	* <p>This will generate a new key pair every time it is called.
	*
	* <p>This method is functionally equivalent to
	* {@link #genKeyPair() genKeyPair}.
	*
	* @return the generated key pair
	*/
	public KeyPair generateKeyPair() {
	// This does nothing (except returning null), because either:
	//
	// 1. the implementation object returned by getInstance() is an
	// instance of KeyPairGenerator which has its own implementation
	// of generateKeyPair (overriding this one), so the application
	// would be calling that method directly, or
	//
	// 2. the implementation returned by getInstance() is an instance
	// of Delegate, in which case generateKeyPair is
	// overridden to invoke the corresponding SPI method.
	//
	// (This is a special case, because in JDK 1.1.x the generateKeyPair
	// method was used both as an API and a SPI method.)
	return null;
	}


	/*
	* The following class allows providers to extend from KeyPairGeneratorSpi
	* rather than from KeyPairGenerator. It represents a KeyPairGenerator
	* with an encapsulated, provider-supplied SPI object (of type
	* KeyPairGeneratorSpi).
	* If the provider implementation is an instance of KeyPairGeneratorSpi,
	* the getInstance() methods above return an instance of this class, with
	* the SPI object encapsulated.
	*
	* Note: All SPI methods from the original KeyPairGenerator class have been
	* moved up the hierarchy into a new class (KeyPairGeneratorSpi), which has
	* been interposed in the hierarchy between the API (KeyPairGenerator)
	* and its original parent (Object).
	*/

	//
	// error failover notes:
	//
	// . we failover if the implementation throws an error during init
	// by retrying the init on other providers
	//
	// . we also failover if the init succeeded but the subsequent call
	// to generateKeyPair() fails. In order for this to work, we need
	// to remember the parameters to the last successful call to init
	// and initialize() the next spi using them.
	//
	// . although not specified, KeyPairGenerators could be thread safe,
	// so we make sure we do not interfere with that
	//
	// . failover is not available, if:
	// . getInstance(algorithm, provider) was used
	// . a provider extends KeyPairGenerator rather than
	// KeyPairGeneratorSpi (JDK 1.1 style)
	// . once getProvider() is called
	//

	private static final class Delegate extends KeyPairGenerator {

	// The provider implementation (delegate)
	private volatile KeyPairGeneratorSpi spi;

	private final Object lock = new Object();

	private Iterator<Service> serviceIterator;

	private static final int I_NONE = 1;
	private static final int I_SIZE = 2;
	private static final int I_PARAMS = 3;

	private int initType;
	private int initKeySize;
	private AlgorithmParameterSpec initParams;
	private SecureRandom initRandom;

	// constructor
	Delegate(KeyPairGeneratorSpi spi, String algorithm) {
	super(algorithm);
	this.spi = spi;
	}

	Delegate(Instance instance, Iterator<Service> serviceIterator,
	String algorithm) {
	super(algorithm);
	spi = (KeyPairGeneratorSpi)instance.impl;
	provider = instance.provider;
	this.serviceIterator = serviceIterator;
	initType = I_NONE;

	if (!skipDebug && pdebug != null) {
	pdebug.println("KeyPairGenerator." + algorithm +
	" algorithm from: " + provider.getName());
	}
	}

	/**
	* Update the active spi of this class and return the next
	* implementation for failover. If no more implemenations are
	* available, this method returns null. However, the active spi of
	* this class is never set to null.
	*/
	private KeyPairGeneratorSpi nextSpi(KeyPairGeneratorSpi oldSpi,
	boolean reinit) {
	synchronized (lock) {
	// somebody else did a failover concurrently
	// try that spi now
	if ((oldSpi != null) && (oldSpi != spi)) {
	return spi;
	}
	if (serviceIterator == null) {
	return null;
	}
	while (serviceIterator.hasNext()) {
	Service s = serviceIterator.next();
	try {
	Object inst = s.newInstance(null);
	// ignore non-spis
	if (inst instanceof KeyPairGeneratorSpi == false) {
	continue;
	}
	if (inst instanceof KeyPairGenerator) {
	continue;
	}
	KeyPairGeneratorSpi spi = (KeyPairGeneratorSpi)inst;
	if (reinit) {
	if (initType == I_SIZE) {
	spi.initialize(initKeySize, initRandom);
	} else if (initType == I_PARAMS) {
	spi.initialize(initParams, initRandom);
	} else if (initType != I_NONE) {
	throw new AssertionError
	("KeyPairGenerator initType: " + initType);
	}
	}
	provider = s.getProvider();
	this.spi = spi;
	return spi;
	} catch (Exception e) {
	// ignore
	}
	}
	disableFailover();
	return null;
	}
	}

	void disableFailover() {
	serviceIterator = null;
	initType = 0;
	initParams = null;
	initRandom = null;
	}

	// engine method
	public void initialize(int keysize, SecureRandom random) {
	if (serviceIterator == null) {
	spi.initialize(keysize, random);
	return;
	}
	RuntimeException failure = null;
	KeyPairGeneratorSpi mySpi = spi;
	do {
	try {
	mySpi.initialize(keysize, random);
	initType = I_SIZE;
	initKeySize = keysize;
	initParams = null;
	initRandom = random;
	return;
	} catch (RuntimeException e) {
	if (failure == null) {
	failure = e;
	}
	mySpi = nextSpi(mySpi, false);
	}
	} while (mySpi != null);
	throw failure;
	}

	// engine method
	public void initialize(AlgorithmParameterSpec params,
	SecureRandom random) throws InvalidAlgorithmParameterException {
	if (serviceIterator == null) {
	spi.initialize(params, random);
	return;
	}
	Exception failure = null;
	KeyPairGeneratorSpi mySpi = spi;
	do {
	try {
	mySpi.initialize(params, random);
	initType = I_PARAMS;
	initKeySize = 0;
	initParams = params;
	initRandom = random;
	return;
	} catch (Exception e) {
	if (failure == null) {
	failure = e;
	}
	mySpi = nextSpi(mySpi, false);
	}
	} while (mySpi != null);
	if (failure instanceof RuntimeException) {
	throw (RuntimeException)failure;
	}
	// must be an InvalidAlgorithmParameterException
	throw (InvalidAlgorithmParameterException)failure;
	}

	// engine method
	public KeyPair generateKeyPair() {
	if (serviceIterator == null) {
	return spi.generateKeyPair();
	}
	RuntimeException failure = null;
	KeyPairGeneratorSpi mySpi = spi;
	do {
	try {
	return mySpi.generateKeyPair();
	} catch (RuntimeException e) {
	if (failure == null) {
	failure = e;
	}
	mySpi = nextSpi(mySpi, true);
	}
	} while (mySpi != null);
	throw failure;
	}
	}

	}

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