/*

 * 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.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</code>)

 * and certificate revocation list (CRL) objects from their encodings.

 *

 * <p>For encodings consisting of multiple certificates, use

 * <code>generateCertificates</code> when you want to

 * parse a collection of possibly unrelated certificates. Otherwise,

 * use <code>generateCertPath</code> when you want to generate

 * a <code>CertPath</code> (a certificate chain) and subsequently

 * validate it with a <code>CertPathValidator</code>.

 *

 * <p>A certificate factory for X.509 must return certificates that are an

 * instance of <code>java.security.cert.X509Certificate</code>, and CRLs

 * that are an instance of <code>java.security.cert.X509CRL</code>.

 *

 * <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</code> (which does not support <code>mark</code>

 * and <code>reset</code>) to a <code>BufferedInputStream</code> (which

 * supports those methods), so that each call to

 * <code>generateCertificate</code> consumes only one certificate, and the

 * read position of the input stream is positioned to the next certificate in

 * the file:<p>

 *

 * <pre>

 * 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:<p>

 *

 * <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> Every implementation of the Java platform is required to support the

 * following standard <code>CertificateFactory</code> type:

 * <ul>

 * <li><tt>X.509</tt></li>

 * </ul>

 * and the following standard <code>CertPath</code> encodings:

 * <ul>

 * <li><tt>PKCS7</tt></li>

 * <li><tt>PkiPath</tt></li>

 * </ul>

 * 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.

 * Consult the release documentation for your implementation to see if any

 * other types or encodings are supported.

 *

 * @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 java.security.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 java.security.Provider

     */

    public static final CertificateFactory getInstance(String type,

            String provider) throws CertificateException,

            NoSuchProviderException {

        try {

            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</code> is

     *          null.

     *

     * @see java.security.Provider

     *

     * @since 1.4

     */

    public static final CertificateFactory getInstance(String type,

            Provider provider) throws CertificateException {

        try {

            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</code>.

     *

     * <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</code> class.

     *

     * <p>In the case of a certificate factory for X.509 certificates, the

     * certificate provided in <code>inStream</code> 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 java.io.InputStream#mark(int) mark} and

     * {@link java.io.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</code> 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</code> 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</code> via its

     * <code>remove</code> method result in an

     * <code>UnsupportedOperationException</code>.

     *

     * @return an <code>Iterator</code> over the names of the supported

     *         <code>CertPath</code> encodings (as <code>String</code>s)

     * @since 1.4

     */

    public final Iterator<String> getCertPathEncodings() {

        return(certFacSpi.engineGetCertPathEncodings());

    }

    /**

     * Generates a <code>CertPath</code> object and initializes it with

     * the data read from the <code>InputStream</code> 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</code> returned by

     * the {@link #getCertPathEncodings getCertPathEncodings} method.

     *

     * @param inStream an <code>InputStream</code> containing the data

     * @return a <code>CertPath</code> initialized with the data from the

     *   <code>InputStream</code>

     * @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</code> object and initializes it with

     * the data read from the <code>InputStream</code> 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</code> containing the data

     * @param encoding the encoding used for the data

     * @return a <code>CertPath</code> initialized with the data from the

     *   <code>InputStream</code>

     * @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</code> object and initializes it with

     * a <code>List</code> of <code>Certificate</code>s.

     * <p>

     * The certificates supplied must be of a type supported by the

     * <code>CertificateFactory</code>. They will be copied out of the supplied

     * <code>List</code> object.

     *

     * @param certificates a <code>List</code> of <code>Certificate</code>s

     * @return a <code>CertPath</code> 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</code>.

     *

     * <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</code> class.

     *

     * <p>In the case of a certificate factory for X.509 certificates,

     * <code>inStream</code> may contain a sequence of DER-encoded certificates

     * in the formats described for

     * {@link #generateCertificate(java.io.InputStream) generateCertificate}.

     * In addition, <code>inStream</code> 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 java.io.InputStream#mark(int) mark} and

     * {@link java.io.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</code>.

     *

     * <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</code> class.

     *

     * <p>Note that if the given input stream does not support

     * {@link java.io.InputStream#mark(int) mark} and

     * {@link java.io.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</code> 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</code>.

     *

     * <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</code> class.

     *

     * <p>In the case of a certificate factory for X.509 CRLs,

     * <code>inStream</code> may contain a sequence of DER-encoded CRLs.

     * In addition, <code>inStream</code> 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 java.io.InputStream#mark(int) mark} and

     * {@link java.io.InputStream#reset() reset}, this method will

     * consume the entire input stream.

     *