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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.util.Objects;
import java.security.Provider;
import java.security.Security;
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 (CertPath) and certificate revocation list (CRL) objects from their encodings. 
For encodings consisting of multiple certificates, use generateCertificates when you want to parse a collection of possibly unrelated certificates. Otherwise, use generateCertPath when you want to generate a CertPath (a certificate chain) and subsequently validate it with a CertPathValidator. 
A certificate factory for X.509 must return certificates that are an instance of java.security.cert.X509Certificate, and CRLs that are an instance of java.security.cert.X509CRL. 
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 FileInputStream (which does not support mark and reset) to a BufferedInputStream (which supports those methods), so that each call to generateCertificate consumes only one certificate, and the read position of the input stream is positioned to the next certificate in the file: 

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());
 }

The following example parses a PKCS#7-formatted certificate reply stored
in a file and extracts all the certificates from it:
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);
}

 Every implementation of the Java platform is required to support the following standard CertificateFactory type: 

X.509
 and the following standard CertPath encodings: 

PKCS7
PkiPath

The type and encodings are described in the 
CertificateFactory section and the 
CertPath Encodings section of the
Java Security Standard Algorithm Names Specification.
Consult the release documentation for your implementation to see if any
other types or encodings are supported.
Author:
Hemma Prafullchandra, Jan Luehe, Sean Mullan
See Also:
Certificate
X509Certificate
CertPath
CRL
X509CRL
Since:
1.2/**
 * 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> Every implementation of the Java platform is required to support the
 * following standard {@code CertificateFactory} type:
 * <ul>
 * <li>{@code X.509}</li>
 * </ul>
 * and the following standard {@code CertPath} encodings:
 * <ul>
 * <li>{@code PKCS7}</li>
 * <li>{@code PkiPath}</li>
 * </ul>
 * The type and encodings are described in the <a href=
 * "{@docRoot}/../specs/security/standard-names.html#certificatefactory-types">
 * CertificateFactory section</a> and the <a href=
 * "{@docRoot}/../specs/security/standard-names.html#certpath-encodings">
 * CertPath Encodings section</a> of the
 * Java Security Standard Algorithm Names Specification.
 * 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.
Params:
certFacSpi – the provider implementation.
provider – the provider.
type – the certificate type./**
     * 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.
 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.
 Note that the list of registered providers may be retrieved via the Security.getProviders() method. 
Params:
type – the name of the requested certificate type.
See the CertificateFactory section in the 
Java Security Standard Algorithm Names Specification
for information about standard certificate types.
Throws:
CertificateException – if no Provider supports a CertificateFactorySpi implementation for the specified type
NullPointerException – if type is null
See Also:
Provider
Implementation Note:
 The JDK Reference Implementation additionally uses the jdk.security.provider.preferred Security property to determine the preferred provider order for the specified algorithm. This may be different than the order of providers returned by Security.getProviders().
Returns:
a certificate factory object for the specified 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.
     *
     * @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 type the name of the requested certificate type.
     * See the CertificateFactory section in the <a href=
     * "{@docRoot}/../specs/security/standard-names.html#certificatefactory-types">
     * Java Security Standard Algorithm Names Specification</a>
     * for information about standard certificate types.
     *
     * @return a certificate factory object for the specified type
     *
     * @throws CertificateException if no {@code Provider} supports a
     *         {@code CertificateFactorySpi} implementation for the
     *         specified type
     *
     * @throws NullPointerException if {@code type} is {@code null}
     *
     * @see java.security.Provider
     */
    public static final CertificateFactory getInstance(String type)
            throws CertificateException {
        Objects.requireNonNull(type, "null type name");
        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.
 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.
 Note that the list of registered providers may be retrieved via the Security.getProviders() method. 
Params:
type – the certificate type.
See the CertificateFactory section in the 
Java Security Standard Algorithm Names Specification
for information about standard certificate types.
provider – the name of the provider.
Throws:
CertificateException – if a CertificateFactorySpi implementation for the specified algorithm is not available from the specified provider
IllegalArgumentException – if the provider name is null or empty
NoSuchProviderException – if the specified provider is not
        registered in the security provider list
NullPointerException – if type is null
See Also:
Provider
Returns:
a certificate factory object for the specified type/**
     * 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}/../specs/security/standard-names.html#certificatefactory-types">
     * Java Security Standard Algorithm Names Specification</a>
     * for information about standard certificate types.
     *
     * @param provider the name of the provider.
     *
     * @return a certificate factory object for the specified type
     *
     * @throws CertificateException if a {@code CertificateFactorySpi}
     *         implementation for the specified algorithm is not
     *         available from the specified provider
     *
     * @throws IllegalArgumentException if the provider name is {@code null}
     *         or empty
     *
     * @throws NoSuchProviderException if the specified provider is not
     *         registered in the security provider list
     *
     * @throws NullPointerException if {@code type} is {@code null}
     *
     * @see java.security.Provider
     */
    public static final CertificateFactory getInstance(String type,
            String provider) throws CertificateException,
            NoSuchProviderException {
        Objects.requireNonNull(type, "null type name");
        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.
 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.
Params:
type – the certificate type.
See the CertificateFactory section in the 
Java Security Standard Algorithm Names Specification
for information about standard certificate types.
provider – the provider.
Throws:
CertificateException – if a CertificateFactorySpi implementation for the specified algorithm is not available from the specified Provider object
IllegalArgumentException – if the provider is null
NullPointerException – if type is null
See Also:
Provider
Returns:
a certificate factory object for the specified type
Since:
1.4/**
     * 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}/../specs/security/standard-names.html#certificatefactory-types">
     * Java Security Standard Algorithm Names Specification</a>
     * for information about standard certificate types.
     * @param provider the provider.
     *
     * @return a certificate factory object for the specified type
     *
     * @throws CertificateException if a {@code CertificateFactorySpi}
     *         implementation for the specified algorithm is not available
     *         from the specified {@code Provider} object
     *
     * @throws IllegalArgumentException if the {@code provider} is
     *         {@code null}
     *
     * @throws NullPointerException if {@code type} is {@code null}
     *
     * @see java.security.Provider
     *
     * @since 1.4
     */
    public static final CertificateFactory getInstance(String type,
            Provider provider) throws CertificateException {
        Objects.requireNonNull(type, "null type name");
        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.
Returns:
the provider of this certificate factory./**
     * 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.
Returns:
the name of the certificate type associated with this
certificate factory./**
     * 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 inStream. 
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 X509Certificate class. 
In the case of a certificate factory for X.509 certificates, the certificate provided in 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-----. 
Note that if the given input stream does not support mark and 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 CertificateException is thrown. 
Params:
inStream – an input stream with the certificate data.
Throws:
CertificateException – on parsing errors.
Returns:
a certificate object initialized with the data
from the input stream./**
     * 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 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} 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 CertPath encodings supported by this certificate factory, with the default encoding first. See the CertPath Encodings section in the 
Java Security Standard Algorithm Names Specification
for information about standard encoding names and their formats.
 Attempts to modify the returned Iterator via its remove method result in an UnsupportedOperationException. 
Returns:
an Iterator over the names of the supported CertPath encodings (as Strings)
Since:
1.4/**
     * 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}/../specs/security/standard-names.html#certpath-encodings">
     * Java Security Standard Algorithm Names Specification</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 CertPath object and initializes it with the data read from the InputStream inStream. The data is assumed to be in the default encoding. The name of the default encoding is the first element of the Iterator returned by the getCertPathEncodings method. 
Params:
inStream – an InputStream containing the data
Throws:
CertificateException – if an exception occurs while decoding
Returns:
a CertPath initialized with the data from the InputStream
Since:
1.4/**
     * 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 CertPath object and initializes it with the data read from the InputStream inStream. The data is assumed to be in the specified encoding. See the CertPath Encodings section in the 
Java Security Standard Algorithm Names Specification
for information about standard encoding names and their formats.
Params:
inStream – an InputStream containing the data
encoding – the encoding used for the data
Throws:
CertificateException – if an exception occurs while decoding or
  the encoding requested is not supported
Returns:
a CertPath initialized with the data from the InputStream
Since:
1.4/**
     * 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}/../specs/security/standard-names.html#certpath-encodings">
     * Java Security Standard Algorithm Names Specification</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 CertPath object and initializes it with a List of Certificates. 
 The certificates supplied must be of a type supported by the CertificateFactory. They will be copied out of the supplied List object. 
Params:
certificates – a List of Certificates
Throws:
CertificateException – if an exception occurs
Returns:
a CertPath initialized with the supplied list of certificates
Since:
1.4/**
     * 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 inStream. 
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 X509Certificate class. 
In the case of a certificate factory for X.509 certificates, inStream may contain a sequence of DER-encoded certificates in the formats described for generateCertificate. In addition, inStream may contain a PKCS#7 certificate chain. This is a PKCS#7 SignedData object, with the only
significant field being certificates. 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.
Note that if the given input stream does not support mark and reset, this method will consume the entire input stream. 
Params:
inStream – the input stream with the certificates.
Throws:
CertificateException – on parsing errors.
Returns:
a (possibly empty) collection view of
java.security.cert.Certificate objects
initialized with the data from the input stream./**
     * 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(java.io.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 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 inStream. 
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 X509CRL class. 
Note that if the given input stream does not support mark and 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 CRLException is thrown. 
Params:
inStream – an input stream with the CRL data.
Throws:
CRLException – on parsing errors.
Returns:
a CRL object initialized with the data
from the input stream./**
     * 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 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} 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 inStream. 
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 X509CRL class. 
In the case of a certificate factory for X.509 CRLs, inStream may contain a sequence of DER-encoded CRLs. In addition, inStream may contain a PKCS#7 CRL set. This is a PKCS#7 SignedData object, with the only
significant field being crls. 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.
Note that if the given input stream does not support mark and reset, this method will consume the entire input stream. 
Params:
inStream – the input stream with the CRLs.
Throws:
CRLException – on parsing errors.
Returns:
a (possibly empty) collection view of
java.security.cert.CRL objects initialized with the data from the input
stream./**
     * 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 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 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);
    }
}