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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  package java.security.cert;
  
  import java.io.InputStream;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.List;
  import java.security.Provider;
  import java.security.Security;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  import java.security.NoSuchAlgorithmException;
  import java.security.NoSuchProviderException;
  
  import sun.security.jca.*;
  import sun.security.jca.GetInstance.Instance;
  
  /**
   * This class defines the functionality of a certificate factory, which is
   * used to generate certificate, certification path ({@code CertPath})
   * and certificate revocation list (CRL) objects from their encodings.
   *
   * <p>For encodings consisting of multiple certificates, use
   * {@code generateCertificates} when you want to
   * parse a collection of possibly unrelated certificates. Otherwise,
   * use {@code generateCertPath} when you want to generate
   * a {@code CertPath} (a certificate chain) and subsequently
   * validate it with a {@code CertPathValidator}.
   *
   * <p>A certificate factory for X.509 must return certificates that are an
   * instance of {@code java.security.cert.X509Certificate}, and CRLs
   * that are an instance of {@code java.security.cert.X509CRL}.
   *
   * <p>The following example reads a file with Base64 encoded certificates,
   * which are each bounded at the beginning by -----BEGIN CERTIFICATE-----, and
   * bounded at the end by -----END CERTIFICATE-----. We convert the
   * {@code FileInputStream} (which does not support {@code mark}
   * and {@code reset}) to a {@code BufferedInputStream} (which
   * supports those methods), so that each call to
   * {@code generateCertificate} consumes only one certificate, and the
   * read position of the input stream is positioned to the next certificate in
   * the file:
   *
   * <pre>{@code
   * FileInputStream fis = new FileInputStream(filename);
   * BufferedInputStream bis = new BufferedInputStream(fis);
   *
   * CertificateFactory cf = CertificateFactory.getInstance("X.509");
   *
   * while (bis.available() > 0) {
   *    Certificate cert = cf.generateCertificate(bis);
   *    System.out.println(cert.toString());
   * }
   * }</pre>
   *
   * <p>The following example parses a PKCS#7-formatted certificate reply stored
   * in a file and extracts all the certificates from it:
   *
   * <pre>
   * FileInputStream fis = new FileInputStream(filename);
   * CertificateFactory cf = CertificateFactory.getInstance("X.509");
   * Collection c = cf.generateCertificates(fis);
   * Iterator i = c.iterator();
   * while (i.hasNext()) {
   *    Certificate cert = (Certificate)i.next();
   *    System.out.println(cert);
   * }
   * </pre>
   *
   * <p> Android provides the following <code>CertificateFactory</code> types:
   * <table>
   *   <thead>
   *     <tr>
   *       <th>Algorithm</th>
   *       <th>Supported API Levels</th>
   *     </tr>
   *   </thead>
   *   <tbody>
   *     <tr>
   *       <td>X.509</td>
   *       <td>1+</td>
   *     </tr>
   *   </tbody>
   * </table>
   * and the following <code>CertPath</code> encodings:
   * <table>
   *     <thead>
   *         <tr>
   *             <th>Name</th>
   *             <th>Supported (API Levels)</th>
   *         </tr>
   *     </thead>
   *     <tbody>
   *         <tr>
   *             <td>PKCS7</td>
   *             <td>1+</td>
   *         </tr>
   *         <tr>
   *             <td>PkiPath</td>
   *             <td>1+</td>
   *         </tr>
   *     </tbody>
   * </table>
   *
   * The type and encodings are described in the <a href=
   * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertificateFactory">
   * CertificateFactory section</a> and the <a href=
   * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertPathEncodings">
   * CertPath Encodings section</a> of the
   * Java Cryptography Architecture Standard Algorithm Name Documentation.
   *
   * @author Hemma Prafullchandra
   * @author Jan Luehe
   * @author Sean Mullan
   *
   * @see Certificate
   * @see X509Certificate
   * @see CertPath
   * @see CRL
   * @see X509CRL
   *
   * @since 1.2
   */
  
  public class CertificateFactory {
  
      // The certificate type
      private String type;
  
      // The provider
      private Provider provider;
  
      // The provider implementation
      private CertificateFactorySpi certFacSpi;
  
      /**
       * Creates a CertificateFactory object of the given type, and encapsulates
       * the given provider implementation (SPI object) in it.
       *
       * @param certFacSpi the provider implementation.
       * @param provider the provider.
       * @param type the certificate type.
       */
      protected CertificateFactory(CertificateFactorySpi certFacSpi,
                                   Provider provider, String type)
      {
          this.certFacSpi = certFacSpi;
          this.provider = provider;
          this.type = type;
      }
  
      /**
       * Returns a certificate factory object that implements the
       * specified certificate type.
       *
       * <p> This method traverses the list of registered security Providers,
       * starting with the most preferred Provider.
       * A new CertificateFactory object encapsulating the
       * CertificateFactorySpi implementation from the first
       * Provider that supports the specified type is returned.
       *
       * <p> Note that the list of registered providers may be retrieved via
       * the {@link Security#getProviders() Security.getProviders()} method.
       *
       * @param type the name of the requested certificate type.
       * See the CertificateFactory section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertificateFactory">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard certificate types.
       *
       * @return a certificate factory object for the specified type.
       *
       * @exception CertificateException if no Provider supports a
       *          CertificateFactorySpi implementation for the
       *          specified type.
       *
       * @see Provider
       */
      public static final CertificateFactory getInstance(String type)
              throws CertificateException {
          try {
              Instance instance = GetInstance.getInstance("CertificateFactory",
                  CertificateFactorySpi.class, type);
              return new CertificateFactory((CertificateFactorySpi)instance.impl,
                  instance.provider, type);
          } catch (NoSuchAlgorithmException e) {
              throw new CertificateException(type + " not found", e);
          }
      }
  
      /**
       * Returns a certificate factory object for the specified
       * certificate type.
       *
       * <p> A new CertificateFactory object encapsulating the
       * CertificateFactorySpi 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 type the certificate type.
       * See the CertificateFactory section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertificateFactory">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard certificate types.
       *
       * @param provider the name of the provider.
       *
       * @return a certificate factory object for the specified type.
       *
       * @exception CertificateException if a CertificateFactorySpi
       *          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 final CertificateFactory getInstance(String type,
              String provider) throws CertificateException,
              NoSuchProviderException {
          try {
              // Android-added: Check for Bouncy Castle deprecation
              Providers.checkBouncyCastleDeprecation(provider, "CertificateFactory", type);
              Instance instance = GetInstance.getInstance("CertificateFactory",
                  CertificateFactorySpi.class, type, provider);
              return new CertificateFactory((CertificateFactorySpi)instance.impl,
                  instance.provider, type);
          } catch (NoSuchAlgorithmException e) {
              throw new CertificateException(type + " not found", e);
          }
      }
  
      /**
       * Returns a certificate factory object for the specified
       * certificate type.
       *
       * <p> A new CertificateFactory object encapsulating the
       * CertificateFactorySpi 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 type the certificate type.
       * See the CertificateFactory section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertificateFactory">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard certificate types.
       * @param provider the provider.
       *
       * @return a certificate factory object for the specified type.
       *
       * @exception CertificateException if a CertificateFactorySpi
       *          implementation for the specified algorithm is not available
       *          from the specified Provider object.
       *
       * @exception IllegalArgumentException if the {@code provider} is
       *          null.
       *
       * @see Provider
       *
       * @since 1.4
       */
      public static final CertificateFactory getInstance(String type,
              Provider provider) throws CertificateException {
          try {
              // Android-added: Check for Bouncy Castle deprecation
              Providers.checkBouncyCastleDeprecation(provider, "CertificateFactory", type);
              Instance instance = GetInstance.getInstance("CertificateFactory",
                  CertificateFactorySpi.class, type, provider);
              return new CertificateFactory((CertificateFactorySpi)instance.impl,
                  instance.provider, type);
          } catch (NoSuchAlgorithmException e) {
              throw new CertificateException(type + " not found", e);
          }
      }
  
      /**
       * Returns the provider of this certificate factory.
       *
       * @return the provider of this certificate factory.
       */
      public final Provider getProvider() {
          return this.provider;
      }
  
      /**
       * Returns the name of the certificate type associated with this
       * certificate factory.
       *
       * @return the name of the certificate type associated with this
       * certificate factory.
       */
      public final String getType() {
          return this.type;
      }
  
      /**
       * Generates a certificate object and initializes it with
       * the data read from the input stream {@code inStream}.
       *
       * <p>In order to take advantage of the specialized certificate format
       * supported by this certificate factory,
       * the returned certificate object can be typecast to the corresponding
       * certificate class. For example, if this certificate
       * factory implements X.509 certificates, the returned certificate object
       * can be typecast to the {@code X509Certificate} class.
       *
       * <p>In the case of a certificate factory for X.509 certificates, the
       * certificate provided in {@code inStream} must be DER-encoded and
       * may be supplied in binary or printable (Base64) encoding. If the
       * certificate is provided in Base64 encoding, it must be bounded at
       * the beginning by -----BEGIN CERTIFICATE-----, and must be bounded at
       * the end by -----END CERTIFICATE-----.
       *
       * <p>Note that if the given input stream does not support
       * {@link InputStream#mark(int) mark} and
       * {@link InputStream#reset() reset}, this method will
       * consume the entire input stream. Otherwise, each call to this
       * method consumes one certificate and the read position of the
       * input stream is positioned to the next available byte after
       * the inherent end-of-certificate marker. If the data in the input stream
       * does not contain an inherent end-of-certificate marker (other
       * than EOF) and there is trailing data after the certificate is parsed, a
       * {@code CertificateException} is thrown.
       *
       * @param inStream an input stream with the certificate data.
       *
       * @return a certificate object initialized with the data
       * from the input stream.
       *
       * @exception CertificateException on parsing errors.
       */
      public final Certificate generateCertificate(InputStream inStream)
          throws CertificateException
      {
          return certFacSpi.engineGenerateCertificate(inStream);
      }
  
      /**
       * Returns an iteration of the {@code CertPath} encodings supported
       * by this certificate factory, with the default encoding first. See
       * the CertPath Encodings section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertPathEncodings">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard encoding names and their formats.
       * <p>
       * Attempts to modify the returned {@code Iterator} via its
       * {@code remove} method result in an
       * {@code UnsupportedOperationException}.
       *
       * @return an {@code Iterator} over the names of the supported
       *         {@code CertPath} encodings (as {@code String}s)
       * @since 1.4
       */
      public final Iterator<String> getCertPathEncodings() {
          return(certFacSpi.engineGetCertPathEncodings());
      }
  
      /**
       * Generates a {@code CertPath} object and initializes it with
       * the data read from the {@code InputStream} inStream. The data
       * is assumed to be in the default encoding. The name of the default
       * encoding is the first element of the {@code Iterator} returned by
       * the {@link #getCertPathEncodings getCertPathEncodings} method.
       *
       * @param inStream an {@code InputStream} containing the data
       * @return a {@code CertPath} initialized with the data from the
       *   {@code InputStream}
       * @exception CertificateException if an exception occurs while decoding
       * @since 1.4
       */
      public final CertPath generateCertPath(InputStream inStream)
          throws CertificateException
      {
          return(certFacSpi.engineGenerateCertPath(inStream));
      }
  
      /**
       * Generates a {@code CertPath} object and initializes it with
       * the data read from the {@code InputStream} inStream. The data
       * is assumed to be in the specified encoding. See
       * the CertPath Encodings section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertPathEncodings">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
       * for information about standard encoding names and their formats.
       *
       * @param inStream an {@code InputStream} containing the data
       * @param encoding the encoding used for the data
       * @return a {@code CertPath} initialized with the data from the
       *   {@code InputStream}
       * @exception CertificateException if an exception occurs while decoding or
       *   the encoding requested is not supported
       * @since 1.4
       */
      public final CertPath generateCertPath(InputStream inStream,
          String encoding) throws CertificateException
      {
          return(certFacSpi.engineGenerateCertPath(inStream, encoding));
      }
  
      /**
       * Generates a {@code CertPath} object and initializes it with
       * a {@code List} of {@code Certificate}s.
       * <p>
       * The certificates supplied must be of a type supported by the
       * {@code CertificateFactory}. They will be copied out of the supplied
       * {@code List} object.
       *
       * @param certificates a {@code List} of {@code Certificate}s
       * @return a {@code CertPath} initialized with the supplied list of
       *   certificates
       * @exception CertificateException if an exception occurs
       * @since 1.4
       */
      public final CertPath
          generateCertPath(List<? extends Certificate> certificates)
          throws CertificateException
      {
          return(certFacSpi.engineGenerateCertPath(certificates));
      }
  
      /**
       * Returns a (possibly empty) collection view of the certificates read
       * from the given input stream {@code inStream}.
       *
       * <p>In order to take advantage of the specialized certificate format
       * supported by this certificate factory, each element in
       * the returned collection view can be typecast to the corresponding
       * certificate class. For example, if this certificate
       * factory implements X.509 certificates, the elements in the returned
       * collection can be typecast to the {@code X509Certificate} class.
       *
       * <p>In the case of a certificate factory for X.509 certificates,
       * {@code inStream} may contain a sequence of DER-encoded certificates
       * in the formats described for
       * {@link #generateCertificate(InputStream) generateCertificate}.
       * In addition, {@code inStream} may contain a PKCS#7 certificate
       * chain. This is a PKCS#7 <i>SignedData</i> object, with the only
       * significant field being <i>certificates</i>. In particular, the
       * signature and the contents are ignored. This format allows multiple
       * certificates to be downloaded at once. If no certificates are present,
       * an empty collection is returned.
       *
       * <p>Note that if the given input stream does not support
       * {@link InputStream#mark(int) mark} and
       * {@link InputStream#reset() reset}, this method will
       * consume the entire input stream.
       *
       * @param inStream the input stream with the certificates.
       *
       * @return a (possibly empty) collection view of
       * java.security.cert.Certificate objects
       * initialized with the data from the input stream.
       *
       * @exception CertificateException on parsing errors.
       */
      public final Collection<? extends Certificate> generateCertificates
              (InputStream inStream) throws CertificateException {
          return certFacSpi.engineGenerateCertificates(inStream);
      }
  
      /**
       * Generates a certificate revocation list (CRL) object and initializes it
       * with the data read from the input stream {@code inStream}.
       *
       * <p>In order to take advantage of the specialized CRL format
       * supported by this certificate factory,
       * the returned CRL object can be typecast to the corresponding
       * CRL class. For example, if this certificate
       * factory implements X.509 CRLs, the returned CRL object
       * can be typecast to the {@code X509CRL} class.
       *
       * <p>Note that if the given input stream does not support
       * {@link InputStream#mark(int) mark} and
       * {@link InputStream#reset() reset}, this method will
       * consume the entire input stream. Otherwise, each call to this
       * method consumes one CRL and the read position of the input stream
       * is positioned to the next available byte after the inherent
       * end-of-CRL marker. If the data in the
       * input stream does not contain an inherent end-of-CRL marker (other
       * than EOF) and there is trailing data after the CRL is parsed, a
       * {@code CRLException} is thrown.
       *
       * @param inStream an input stream with the CRL data.
       *
       * @return a CRL object initialized with the data
       * from the input stream.
       *
       * @exception CRLException on parsing errors.
       */
      public final CRL generateCRL(InputStream inStream)
          throws CRLException
      {
          return certFacSpi.engineGenerateCRL(inStream);
      }
  
      /**
       * Returns a (possibly empty) collection view of the CRLs read
       * from the given input stream {@code inStream}.
       *
       * <p>In order to take advantage of the specialized CRL format
       * supported by this certificate factory, each element in
       * the returned collection view can be typecast to the corresponding
       * CRL class. For example, if this certificate
       * factory implements X.509 CRLs, the elements in the returned
       * collection can be typecast to the {@code X509CRL} class.
       *
       * <p>In the case of a certificate factory for X.509 CRLs,
       * {@code inStream} may contain a sequence of DER-encoded CRLs.
       * In addition, {@code inStream} may contain a PKCS#7 CRL
       * set. This is a PKCS#7 <i>SignedData</i> object, with the only
       * significant field being <i>crls</i>. In particular, the
       * signature and the contents are ignored. This format allows multiple
       * CRLs to be downloaded at once. If no CRLs are present,
       * an empty collection is returned.
       *
       * <p>Note that if the given input stream does not support
       * {@link InputStream#mark(int) mark} and
       * {@link InputStream#reset() reset}, this method will
       * consume the entire input stream.
       *
       * @param inStream the input stream with the CRLs.
       *
       * @return a (possibly empty) collection view of
       * java.security.cert.CRL objects initialized with the data from the input
       * stream.
       *
       * @exception CRLException on parsing errors.
       */
      public final Collection<? extends CRL> generateCRLs(InputStream inStream)
              throws CRLException {
          return certFacSpi.engineGenerateCRLs(inStream);
      }
  }
  