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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
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	* questions.
	*/

	package java.security;

	import java.io.*;
	import java.security.spec.AlgorithmParameterSpec;
	import java.security.spec.InvalidParameterSpecException;
	import java.util.Objects;

	/**
	* This class is used as an opaque representation of cryptographic parameters.
	*
	* <p>An {@code AlgorithmParameters} object for managing the parameters
	* for a particular algorithm can be obtained by
	* calling one of the {@code getInstance} factory methods
	* (static methods that return instances of a given class).
	*
	* <p>Once an {@code AlgorithmParameters} object is obtained, it must be
	* initialized via a call to {@code init}, using an appropriate parameter
	* specification or parameter encoding.
	*
	* <p>A transparent parameter specification is obtained from an
	* {@code AlgorithmParameters} object via a call to
	* {@code getParameterSpec}, and a byte encoding of the parameters is
	* obtained via a call to {@code getEncoded}.
	*
	* <p> Every implementation of the Java platform is required to support the
	* following standard {@code AlgorithmParameters} algorithms:
	* <ul>
	* <li>{@code AES}</li>
	* <li>{@code DES}</li>
	* <li>{@code DESede}</li>
	* <li>{@code DiffieHellman}</li>
	* <li>{@code DSA}</li>
	* </ul>
	* These algorithms are described in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
	* AlgorithmParameters 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 Jan Luehe
	*
	*
	* @see java.security.spec.AlgorithmParameterSpec
	* @see java.security.spec.DSAParameterSpec
	* @see KeyPairGenerator
	*
	* @since 1.2
	*/

	public class AlgorithmParameters {

	// The provider
	private Provider provider;

	// The provider implementation (delegate)
	private AlgorithmParametersSpi paramSpi;

	// The algorithm
	private String algorithm;

	// Has this object been initialized?
	private boolean initialized = false;

	/**
	* Creates an AlgorithmParameters object.
	*
	* @param paramSpi the delegate
	* @param provider the provider
	* @param algorithm the algorithm
	*/
	protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
	Provider provider, String algorithm)
	{
	this.paramSpi = paramSpi;
	this.provider = provider;
	this.algorithm = algorithm;
	}

	/**
	* Returns the name of the algorithm associated with this parameter object.
	*
	* @return the algorithm name.
	*/
	public final String getAlgorithm() {
	return this.algorithm;
	}

	/**
	* Returns a parameter object for the specified algorithm.
	*
	* <p> This method traverses the list of registered security Providers,
	* starting with the most preferred Provider.
	* A new AlgorithmParameters object encapsulating the
	* AlgorithmParametersSpi 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.
	*
	* <p> The returned parameter object must be initialized via a call to
	* {@code init}, using an appropriate parameter specification or
	* parameter encoding.
	*
	* @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 name of the algorithm requested.
	* See the AlgorithmParameters section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*
	* @return the new parameter object
	*
	* @throws NoSuchAlgorithmException if no {@code Provider} supports an
	* {@code AlgorithmParametersSpi} implementation for the
	* specified algorithm
	*
	* @throws NullPointerException if {@code algorithm} is {@code null}
	*
	* @see Provider
	*/
	public static AlgorithmParameters getInstance(String algorithm)
	throws NoSuchAlgorithmException {
	Objects.requireNonNull(algorithm, "null algorithm name");
	try {
	Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
	(String)null);
	return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
	(Provider)objs[1],
	algorithm);
	} catch(NoSuchProviderException e) {
	throw new NoSuchAlgorithmException(algorithm + " not found");
	}
	}

	/**
	* Returns a parameter object for the specified algorithm.
	*
	* <p> A new AlgorithmParameters object encapsulating the
	* AlgorithmParametersSpi 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.
	*
	* <p>The returned parameter object must be initialized via a call to
	* {@code init}, using an appropriate parameter specification or
	* parameter encoding.
	*
	* @param algorithm the name of the algorithm requested.
	* See the AlgorithmParameters section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*
	* @param provider the name of the provider.
	*
	* @return the new parameter object
	*
	* @throws IllegalArgumentException if the provider name is {@code null}
	* or empty
	*
	* @throws NoSuchAlgorithmException if an {@code AlgorithmParametersSpi}
	* 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 AlgorithmParameters getInstance(String algorithm,
	String provider)
	throws NoSuchAlgorithmException, NoSuchProviderException
	{
	Objects.requireNonNull(algorithm, "null algorithm name");
	if (provider == null \|\| provider.length() == 0)
	throw new IllegalArgumentException("missing provider");
	Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
	provider);
	return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
	(Provider)objs[1],
	algorithm);
	}

	/**
	* Returns a parameter object for the specified algorithm.
	*
	* <p> A new AlgorithmParameters object encapsulating the
	* AlgorithmParametersSpi implementation from the specified Provider
	* object is returned. Note that the specified Provider object
	* does not have to be registered in the provider list.
	*
	* <p>The returned parameter object must be initialized via a call to
	* {@code init}, using an appropriate parameter specification or
	* parameter encoding.
	*
	* @param algorithm the name of the algorithm requested.
	* See the AlgorithmParameters section in the <a href=
	* "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
	* Java Security Standard Algorithm Names Specification</a>
	* for information about standard algorithm names.
	*
	* @param provider the name of the provider.
	*
	* @return the new parameter object
	*
	* @throws IllegalArgumentException if the provider is {@code null}
	*
	* @throws NoSuchAlgorithmException if an
	* {@code AlgorithmParameterGeneratorSpi}
	* 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 AlgorithmParameters getInstance(String algorithm,
	Provider provider)
	throws NoSuchAlgorithmException
	{
	Objects.requireNonNull(algorithm, "null algorithm name");
	if (provider == null)
	throw new IllegalArgumentException("missing provider");
	Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
	provider);
	return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
	(Provider)objs[1],
	algorithm);
	}

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

	/**
	* Initializes this parameter object using the parameters
	* specified in {@code paramSpec}.
	*
	* @param paramSpec the parameter specification.
	*
	* @exception InvalidParameterSpecException if the given parameter
	* specification is inappropriate for the initialization of this parameter
	* object, or if this parameter object has already been initialized.
	*/
	public final void init(AlgorithmParameterSpec paramSpec)
	throws InvalidParameterSpecException
	{
	if (this.initialized)
	throw new InvalidParameterSpecException("already initialized");
	paramSpi.engineInit(paramSpec);
	this.initialized = true;
	}

	/**
	* Imports the specified parameters and decodes them according to the
	* primary decoding format for parameters. The primary decoding
	* format for parameters is ASN.1, if an ASN.1 specification for this type
	* of parameters exists.
	*
	* @param params the encoded parameters.
	*
	* @exception IOException on decoding errors, or if this parameter object
	* has already been initialized.
	*/
	public final void init(byte[] params) throws IOException {
	if (this.initialized)
	throw new IOException("already initialized");
	paramSpi.engineInit(params);
	this.initialized = true;
	}

	/**
	* Imports the parameters from {@code params} and decodes them
	* according to the specified decoding scheme.
	* If {@code format} is null, the
	* primary decoding format for parameters is used. The primary decoding
	* format is ASN.1, if an ASN.1 specification for these parameters
	* exists.
	*
	* @param params the encoded parameters.
	*
	* @param format the name of the decoding scheme.
	*
	* @exception IOException on decoding errors, or if this parameter object
	* has already been initialized.
	*/
	public final void init(byte[] params, String format) throws IOException {
	if (this.initialized)
	throw new IOException("already initialized");
	paramSpi.engineInit(params, format);
	this.initialized = true;
	}

	/**
	* Returns a (transparent) specification of this parameter object.
	* {@code paramSpec} identifies the specification class in which
	* the parameters should be returned. It could, for example, be
	* {@code DSAParameterSpec.class}, to indicate that the
	* parameters should be returned in an instance of the
	* {@code DSAParameterSpec} class.
	*
	* @param <T> the type of the parameter specification to be returrned
	* @param paramSpec the specification class in which
	* the parameters should be returned.
	*
	* @return the parameter specification.
	*
	* @exception InvalidParameterSpecException if the requested parameter
	* specification is inappropriate for this parameter object, or if this
	* parameter object has not been initialized.
	*/
	public final <T extends AlgorithmParameterSpec>
	T getParameterSpec(Class<T> paramSpec)
	throws InvalidParameterSpecException
	{
	if (this.initialized == false) {
	throw new InvalidParameterSpecException("not initialized");
	}
	return paramSpi.engineGetParameterSpec(paramSpec);
	}

	/**
	* Returns the parameters in their primary encoding format.
	* The primary encoding format for parameters is ASN.1, if an ASN.1
	* specification for this type of parameters exists.
	*
	* @return the parameters encoded using their primary encoding format.
	*
	* @exception IOException on encoding errors, or if this parameter object
	* has not been initialized.
	*/
	public final byte[] getEncoded() throws IOException
	{
	if (this.initialized == false) {
	throw new IOException("not initialized");
	}
	return paramSpi.engineGetEncoded();
	}

	/**
	* Returns the parameters encoded in the specified scheme.
	* If {@code format} is null, the
	* primary encoding format for parameters is used. The primary encoding
	* format is ASN.1, if an ASN.1 specification for these parameters
	* exists.
	*
	* @param format the name of the encoding format.
	*
	* @return the parameters encoded using the specified encoding scheme.
	*
	* @exception IOException on encoding errors, or if this parameter object
	* has not been initialized.
	*/
	public final byte[] getEncoded(String format) throws IOException
	{
	if (this.initialized == false) {
	throw new IOException("not initialized");
	}
	return paramSpi.engineGetEncoded(format);
	}

	/**
	* Returns a formatted string describing the parameters.
	*
	* @return a formatted string describing the parameters, or null if this
	* parameter object has not been initialized.
	*/
	public final String toString() {
	if (this.initialized == false) {
	return null;
	}
	return paramSpi.engineToString();
	}
	}

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