content: /*
   * Copyright (c) 1997, 2013, 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.Provider.Service;
  import java.security.spec.KeySpec;
  import java.security.spec.InvalidKeySpecException;
  import java.security.spec.RSAPrivateKeySpec;
  
  import sun.security.util.Debug;
  import sun.security.jca.*;
  import sun.security.jca.GetInstance.Instance;
  
  /**
   * Key factories are used to convert <I>keys</I> (opaque
   * cryptographic keys of type {@code Key}) into <I>key specifications</I>
   * (transparent representations of the underlying key material), and vice
   * versa.
   *
   * <P> Key factories are bi-directional. That is, they allow you to build an
   * opaque key object from a given key specification (key material), or to
   * retrieve the underlying key material of a key object in a suitable format.
   *
   * <P> Multiple compatible key specifications may exist for the same key.
   * For example, a DSA public key may be specified using
   * {@code DSAPublicKeySpec} or
   * {@code X509EncodedKeySpec}. A key factory can be used to translate
   * between compatible key specifications.
   *
   * <P> The following is an example of how to use a key factory in order to
   * instantiate a DSA public key from its encoding.
   * Assume Alice has received a digital signature from Bob.
   * Bob also sent her his public key (in encoded format) to verify
   * his signature. Alice then performs the following actions:
   *
   * <pre>
   * X509EncodedKeySpec bobPubKeySpec = new X509EncodedKeySpec(bobEncodedPubKey);
   * KeyFactory keyFactory = KeyFactory.getInstance("DSA");
   * PublicKey bobPubKey = keyFactory.generatePublic(bobPubKeySpec);
   * Signature sig = Signature.getInstance("DSA");
   * sig.initVerify(bobPubKey);
   * sig.update(data);
   * sig.verify(signature);
   * </pre>
   *
   * <p> Android provides the following <code>KeyFactory</code> algorithms:
   * <table>
   *   <thead>
   *     <tr>
   *       <th>Algorithm</th>
   *       <th>Supported API Levels</th>
   *     </tr>
   *   </thead>
   *   <tbody>
   *     <tr>
   *       <td>DH</td>
   *       <td>1+</td>
   *     </tr>
   *     <tr>
   *       <td>DSA</td>
   *       <td>1+</td>
   *     </tr>
   *     <tr>
   *       <td>EC</td>
   *       <td>11+</td>
   *     </tr>
   *     <tr>
   *       <td>RSA</td>
   *       <td>1+</td>
   *     </tr>
   *     <tr class="deprecated">
   *       <td>X.509</td>
   *       <td>1-8</td>
   *     </tr>
   *   </tbody>
   * </table>
   *
   * These algorithms are described in the <a href=
   * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyFactory">
   * KeyFactory section</a> of the
   * Java Cryptography Architecture Standard Algorithm Name Documentation.
   *
   * @author Jan Luehe
   *
   * @see Key
   * @see PublicKey
   * @see PrivateKey
   * @see KeySpec
   * @see java.security.spec.DSAPublicKeySpec
   * @see java.security.spec.X509EncodedKeySpec
   *
   * @since 1.2
   */
  
  public class KeyFactory {
  
      private static final Debug debug =
                          Debug.getInstance("jca", "KeyFactory");
  
      // The algorithm associated with this key factory
      private final String algorithm;
  
      // The provider
      private Provider provider;
  
      // The provider implementation (delegate)
      private volatile KeyFactorySpi spi;
  
      // lock for mutex during provider selection
      private final Object lock = new Object();
  
      // remaining services to try in provider selection
      // null once provider is selected
      private Iterator<Service> serviceIterator;
  
      /**
       * Creates a KeyFactory object.
       *
       * @param keyFacSpi the delegate
       * @param provider the provider
       * @param algorithm the name of the algorithm
       * to associate with this {@code KeyFactory}
       */
      protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider,
                           String algorithm) {
          this.spi = keyFacSpi;
          this.provider = provider;
          this.algorithm = algorithm;
      }
  
      private KeyFactory(String algorithm) throws NoSuchAlgorithmException {
          this.algorithm = algorithm;
          List<Service> list = GetInstance.getServices("KeyFactory", algorithm);
          serviceIterator = list.iterator();
          // fetch and instantiate initial spi
          if (nextSpi(null) == null) {
              throw new NoSuchAlgorithmException
                  (algorithm + " KeyFactory not available");
          }
      }
  
      /**
       * Returns a KeyFactory object that converts
       * public/private keys of the specified algorithm.
       *
       * <p> This method traverses the list of registered security Providers,
       * starting with the most preferred Provider.
       * A new KeyFactory object encapsulating the
       * KeyFactorySpi 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.
       *
       * @param algorithm the name of the requested key algorithm.
       * See the KeyFactory section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyFactory">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard algorithm names.
       *
       * @return the new KeyFactory object.
       *
       * @exception NoSuchAlgorithmException if no Provider supports a
       *          KeyFactorySpi implementation for the
       *          specified algorithm.
       *
       * @see Provider
       */
      public static KeyFactory getInstance(String algorithm)
              throws NoSuchAlgorithmException {
          return new KeyFactory(algorithm);
      }
  
      /**
       * Returns a KeyFactory object that converts
       * public/private keys of the specified algorithm.
       *
       * <p> A new KeyFactory object encapsulating the
       * KeyFactorySpi 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 name of the requested key algorithm.
       * See the KeyFactory section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyFactory">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard algorithm names.
       *
       * @param provider the name of the provider.
       *
       * @return the new KeyFactory object.
       *
       * @exception NoSuchAlgorithmException if a KeyFactorySpi
       *          implementation for the specified algorithm is not
       *          available from the specified provider.
       *
       * @exception NoSuchProviderException if the specified provider is not
       *          registered in the security provider list.
       *
       * @exception IllegalArgumentException if the provider name is null
       *          or empty.
       *
       * @see Provider
       */
      public static KeyFactory getInstance(String algorithm, String provider)
              throws NoSuchAlgorithmException, NoSuchProviderException {
          // Android-added: Check for Bouncy Castle deprecation
          Providers.checkBouncyCastleDeprecation(provider, "KeyFactory", algorithm);
          Instance instance = GetInstance.getInstance("KeyFactory",
              KeyFactorySpi.class, algorithm, provider);
          return new KeyFactory((KeyFactorySpi)instance.impl,
              instance.provider, algorithm);
      }
  
      /**
       * Returns a KeyFactory object that converts
       * public/private keys of the specified algorithm.
       *
       * <p> A new KeyFactory object encapsulating the
       * KeyFactorySpi 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 name of the requested key algorithm.
       * See the KeyFactory section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyFactory">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard algorithm names.
       *
       * @param provider the provider.
       *
       * @return the new KeyFactory object.
       *
       * @exception NoSuchAlgorithmException if a KeyFactorySpi
       *          implementation for the specified algorithm is not available
       *          from the specified Provider object.
       *
       * @exception IllegalArgumentException if the specified provider is null.
       *
       * @see Provider
       *
       * @since 1.4
       */
      public static KeyFactory getInstance(String algorithm, Provider provider)
              throws NoSuchAlgorithmException {
          // Android-added: Check for Bouncy Castle deprecation
          Providers.checkBouncyCastleDeprecation(provider, "KeyFactory", algorithm);
          Instance instance = GetInstance.getInstance("KeyFactory",
              KeyFactorySpi.class, algorithm, provider);
          return new KeyFactory((KeyFactorySpi)instance.impl,
              instance.provider, algorithm);
      }
  
      /**
       * Returns the provider of this key factory object.
       *
       * @return the provider of this key factory object
       */
      public final Provider getProvider() {
          synchronized (lock) {
              // disable further failover after this call
              serviceIterator = null;
              return provider;
          }
      }
  
      /**
       * Gets the name of the algorithm
       * associated with this {@code KeyFactory}.
       *
       * @return the name of the algorithm associated with this
       * {@code KeyFactory}
       */
      public final String getAlgorithm() {
          return this.algorithm;
      }
  
      /**
       * Update the active KeyFactorySpi 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 KeyFactorySpi nextSpi(KeyFactorySpi oldSpi) {
          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 obj = s.newInstance(null);
                      if (obj instanceof KeyFactorySpi == false) {
                          continue;
                      }
                      KeyFactorySpi spi = (KeyFactorySpi)obj;
                      provider = s.getProvider();
                      this.spi = spi;
                      return spi;
                  } catch (NoSuchAlgorithmException e) {
                      // ignore
                  }
              }
              serviceIterator = null;
              return null;
          }
      }
  
      /**
       * Generates a public key object from the provided key specification
       * (key material).
       *
       * @param keySpec the specification (key material) of the public key.
       *
       * @return the public key.
       *
       * @exception InvalidKeySpecException if the given key specification
       * is inappropriate for this key factory to produce a public key.
       */
      public final PublicKey generatePublic(KeySpec keySpec)
              throws InvalidKeySpecException {
          if (serviceIterator == null) {
              return spi.engineGeneratePublic(keySpec);
          }
          Exception failure = null;
          KeyFactorySpi mySpi = spi;
          do {
              try {
                  return mySpi.engineGeneratePublic(keySpec);
              } catch (Exception e) {
                  if (failure == null) {
                      failure = e;
                  }
                  mySpi = nextSpi(mySpi);
              }
          } while (mySpi != null);
          if (failure instanceof RuntimeException) {
              throw (RuntimeException)failure;
          }
          if (failure instanceof InvalidKeySpecException) {
              throw (InvalidKeySpecException)failure;
          }
          throw new InvalidKeySpecException
                  ("Could not generate public key", failure);
      }
  
      /**
       * Generates a private key object from the provided key specification
       * (key material).
       *
       * @param keySpec the specification (key material) of the private key.
       *
       * @return the private key.
       *
       * @exception InvalidKeySpecException if the given key specification
       * is inappropriate for this key factory to produce a private key.
       */
      public final PrivateKey generatePrivate(KeySpec keySpec)
              throws InvalidKeySpecException {
          if (serviceIterator == null) {
              return spi.engineGeneratePrivate(keySpec);
          }
          Exception failure = null;
          KeyFactorySpi mySpi = spi;
          do {
              try {
                  return mySpi.engineGeneratePrivate(keySpec);
              } catch (Exception e) {
                  if (failure == null) {
                      failure = e;
                  }
                  mySpi = nextSpi(mySpi);
              }
          } while (mySpi != null);
          if (failure instanceof RuntimeException) {
              throw (RuntimeException)failure;
          }
          if (failure instanceof InvalidKeySpecException) {
              throw (InvalidKeySpecException)failure;
          }
          throw new InvalidKeySpecException
                  ("Could not generate private key", failure);
      }
  
      /**
       * Returns a specification (key material) of the given key object.
       * {@code keySpec} identifies the specification class in which
       * the key material should be returned. It could, for example, be
       * {@code DSAPublicKeySpec.class}, to indicate that the
       * key material should be returned in an instance of the
       * {@code DSAPublicKeySpec} class.
       *
       * @param <T> the type of the key specification to be returned
       *
       * @param key the key.
       *
       * @param keySpec the specification class in which
       * the key material should be returned.
       *
       * @return the underlying key specification (key material) in an instance
       * of the requested specification class.
       *
       * @exception InvalidKeySpecException if the requested key specification is
       * inappropriate for the given key, or the given key cannot be processed
       * (e.g., the given key has an unrecognized algorithm or format).
       */
      public final <T extends KeySpec> T getKeySpec(Key key, Class<T> keySpec)
              throws InvalidKeySpecException {
          if (serviceIterator == null) {
              return spi.engineGetKeySpec(key, keySpec);
          }
          Exception failure = null;
          KeyFactorySpi mySpi = spi;
          do {
              try {
                  return mySpi.engineGetKeySpec(key, keySpec);
              } catch (Exception e) {
                  if (failure == null) {
                      failure = e;
                  }
                  mySpi = nextSpi(mySpi);
              }
          } while (mySpi != null);
          if (failure instanceof RuntimeException) {
              throw (RuntimeException)failure;
          }
          if (failure instanceof InvalidKeySpecException) {
              throw (InvalidKeySpecException)failure;
          }
          throw new InvalidKeySpecException
                  ("Could not get key spec", failure);
      }
  
      /**
       * Translates a key object, whose provider may be unknown or potentially
       * untrusted, into a corresponding key object of this key factory.
       *
       * @param key the key whose provider is unknown or untrusted.
       *
       * @return the translated key.
       *
       * @exception InvalidKeyException if the given key cannot be processed
       * by this key factory.
       */
      public final Key translateKey(Key key) throws InvalidKeyException {
          if (serviceIterator == null) {
              return spi.engineTranslateKey(key);
          }
          Exception failure = null;
          KeyFactorySpi mySpi = spi;
          do {
              try {
                  return mySpi.engineTranslateKey(key);
              } catch (Exception e) {
                  if (failure == null) {
                      failure = e;
                  }
                  mySpi = nextSpi(mySpi);
              }
          } while (mySpi != null);
          if (failure instanceof RuntimeException) {
              throw (RuntimeException)failure;
          }
          if (failure instanceof InvalidKeyException) {
              throw (InvalidKeyException)failure;
          }
          throw new InvalidKeyException
                  ("Could not translate key", failure);
      }
  
  }
  