mirror of git://gcc.gnu.org/git/gcc.git
295 lines
11 KiB
Java
295 lines
11 KiB
Java
/* KeyFactory.java --- Key Factory Class
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Copyright (C) 1999, 2003 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.security;
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import java.security.spec.KeySpec;
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import java.security.spec.InvalidKeySpecException;
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import java.security.NoSuchAlgorithmException;
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import gnu.java.security.Engine;
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/**
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* <p>Key factories are used to convert keys (opaque cryptographic keys of type
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* {@link Key}) into key specifications (transparent representations of the
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* underlying key material), and vice versa.</p>
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*
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* <p>Key factories are bi-directional. That is, they allow you to build an
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* opaque key object from a given key specification (key material), or to
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* retrieve the underlying key material of a key object in a suitable format.</p>
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*
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* <p>Multiple compatible key specifications may exist for the same key. For
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* example, a <i>DSA</i> public key may be specified using {@link
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* java.security.spec.DSAPublicKeySpec} or {@link
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* java.security.spec.X509EncodedKeySpec}. A key factory can be used to
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* translate between compatible key specifications.</p>
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*
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* <p>The following is an example of how to use a key factory in order to
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* instantiate a <i>DSA</i> public key from its encoding. Assume Alice has
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* received a digital signature from Bob. Bob also sent her his public key (in
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* encoded format) to verify his signature. Alice then performs the following
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* actions:
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*
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* <pre>
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* X509EncodedKeySpec bobPubKeySpec = new X509EncodedKeySpec(bobEncodedPubKey);
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* KeyFactory keyFactory = KeyFactory.getInstance("DSA");
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* PublicKey bobPubKey = keyFactory.generatePublic(bobPubKeySpec);
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* Signature sig = Signature.getInstance("DSA");
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* sig.initVerify(bobPubKey);
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* sig.update(data);
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* sig.verify(signature);
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* </pre>
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*
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* @since 1.2
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* @see Key
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* @see PublicKey
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* @see PrivateKey
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* @see KeySpec
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* @see java.security.spec.DSAPublicKeySpec
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* @see java.security.spec.X509EncodedKeySpec
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@author Mark Benvenuto
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*/
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public class KeyFactory
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{
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/** The service name for key factories. */
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private static final String KEY_FACTORY = "KeyFactory";
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private KeyFactorySpi keyFacSpi;
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private Provider provider;
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private String algorithm;
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/**
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* Creates a <code>KeyFactory</code> object.
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*
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* @param keyFacSpi the delegate.
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* @param provider the provider.
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* @param algorithm the name of the algorithm to associate with this
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* <code>KeyFactory</code>.
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*/
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protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider,
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String algorithm)
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{
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this.keyFacSpi = keyFacSpi;
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this.provider = provider;
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this.algorithm = algorithm;
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}
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/**
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* Generates a <code>KeyFactory</code> object that implements the specified
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* algorithm. If the default provider package provides an implementation of
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* the requested algorithm, an instance of <code>KeyFactory</code> containing
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* that implementation is returned. If the algorithm is not available in the
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* default package, other packages are searched.
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*
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* @param algorithm the name of the requested key algorithm. See Appendix A
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* in the Java Cryptography Architecture API Specification & Reference
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* for information about standard algorithm names.
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* @return a <code>KeyFactory</code> object for the specified algorithm.
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* @throws NoSuchAlgorithmException if the requested algorithm is not
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* available in the default provider package or any of the other provider
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* packages that were searched.
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*/
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public static KeyFactory getInstance(String algorithm)
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throws NoSuchAlgorithmException
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{
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Provider[] p = Security.getProviders();
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for (int i = 0; i < p.length; i++)
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try
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{
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return getInstance(algorithm, p[i]);
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}
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catch (NoSuchAlgorithmException ignored) {}
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throw new NoSuchAlgorithmException(algorithm);
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}
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/**
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* Generates a <code>KeyFactory</code> object for the specified algorithm
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* from the specified provider.
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*
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* @param algorithm the name of the requested key algorithm. See Appendix A
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* in the Java Cryptography Architecture API Specification & Reference
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* for information about standard algorithm names.
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* @param provider the name of the provider.
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* @return a <code>KeyFactory</code> object for the specified algorithm.
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* @throws NoSuchAlgorithmException if the algorithm is not available from
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* the specified provider.
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* @throws NoSuchProviderException if the provider has not been configured.
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* @throws IllegalArgumentException if the provider name is null or empty.
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* @see Provider
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*/
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public static KeyFactory getInstance(String algorithm, String provider)
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throws NoSuchAlgorithmException, NoSuchProviderException
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{
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if (provider == null || provider.length() == 0)
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throw new IllegalArgumentException("Illegal provider");
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Provider p = Security.getProvider(provider);
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if (p == null)
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throw new NoSuchProviderException();
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return getInstance(algorithm, p);
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}
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/**
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* Generates a <code>KeyFactory</code> object for the specified algorithm from
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* the specified provider. Note: the <code>provider</code> doesn't have to be
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* registered.
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*
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* @param algorithm the name of the requested key algorithm. See Appendix A
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* in the Java Cryptography Architecture API Specification & Reference for
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* information about standard algorithm names.
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* @param provider the provider.
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* @return a <code>KeyFactory</code> object for the specified algorithm.
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* @throws NoSuchAlgorithmException if the algorithm is not available from
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* the specified provider.
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* @throws IllegalArgumentException if the <code>provider</code> is
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* <code>null</code>.
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* @since 1.4
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* @see Provider
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*/
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public static KeyFactory getInstance(String algorithm, Provider provider)
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throws NoSuchAlgorithmException
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{
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if (provider == null)
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throw new IllegalArgumentException("Illegal provider");
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try
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{
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return new KeyFactory((KeyFactorySpi)
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Engine.getInstance(KEY_FACTORY, algorithm, provider),
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provider, algorithm);
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}
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catch (java.lang.reflect.InvocationTargetException ite)
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{
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throw new NoSuchAlgorithmException(algorithm);
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}
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catch (ClassCastException cce)
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{
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throw new NoSuchAlgorithmException(algorithm);
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}
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}
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/**
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* Returns the provider of this key factory object.
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*
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* @return the provider of this key factory object.
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*/
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public final Provider getProvider()
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{
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return provider;
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}
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/**
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* Gets the name of the algorithm associated with this <code>KeyFactory</code>.
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*
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* @return the name of the algorithm associated with this
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* <code>KeyFactory</code>.
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*/
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public final String getAlgorithm()
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{
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return algorithm;
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}
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/**
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* Generates a public key object from the provided key specification (key
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* material).
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*
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* @param keySpec the specification (key material) of the public key.
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* @return the public key.
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* @throws InvalidKeySpecException if the given key specification is
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* inappropriate for this key factory to produce a public key.
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*/
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public final PublicKey generatePublic(KeySpec keySpec)
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throws InvalidKeySpecException
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{
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return keyFacSpi.engineGeneratePublic(keySpec);
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}
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/**
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* Generates a private key object from the provided key specification (key
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* material).
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*
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* @param keySpec the specification (key material) of the private key.
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* @return the private key.
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* @throws InvalidKeySpecException if the given key specification is
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* inappropriate for this key factory to produce a private key.
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*/
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public final PrivateKey generatePrivate(KeySpec keySpec)
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throws InvalidKeySpecException
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{
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return keyFacSpi.engineGeneratePrivate(keySpec);
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}
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/**
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* Returns a specification (key material) of the given key object.
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* <code>keySpec</code> identifies the specification class in which the key
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* material should be returned. It could, for example, be
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* <code>DSAPublicKeySpec.class</code>, to indicate that the key material
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* should be returned in an instance of the {@link
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* java.security.spec.DSAPublicKeySpec} class.
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*
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* @param key the key.
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* @param keySpec the specification class in which the key material should be
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* returned.
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* @return the underlying key specification (key material) in an instance of
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* the requested specification class.
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* @throws InvalidKeySpecException if the requested key specification is
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* inappropriate for the given key, or the given key cannot be processed
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* (e.g., the given key has an unrecognized algorithm or format).
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*/
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public final KeySpec getKeySpec(Key key, Class keySpec)
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throws InvalidKeySpecException
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{
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return keyFacSpi.engineGetKeySpec(key, keySpec);
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}
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/**
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* Translates a key object, whose provider may be unknown or potentially
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* untrusted, into a corresponding key object of this key factory.
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*
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* @param key the key whose provider is unknown or untrusted.
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* @return the translated key.
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* @throws InvalidKeyException if the given key cannot be processed by this
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* key factory.
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*/
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public final Key translateKey(Key key) throws InvalidKeyException
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{
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return keyFacSpi.engineTranslateKey(key);
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}
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}
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