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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.NoSuchAlgorithmException;

import java.security.NoSuchProviderException;

/**

 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)

 * for the <code>CertificateFactory</code> class.

 * All the abstract methods in this class must be implemented by each

 * cryptographic service provider who wishes to supply the implementation

 * of a certificate factory for a particular certificate type, e.g., X.509.

 *

 * <p>Certificate factories are used to generate certificate, certification path

 * (<code>CertPath</code>) and certificate revocation list (CRL) objects from

 * their encodings.

 *

 * <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>.

 *

 * @author Hemma Prafullchandra

 * @author Jan Luehe

 * @author Sean Mullan

 *

 *

 * @see CertificateFactory

 * @see Certificate

 * @see X509Certificate

 * @see CertPath

 * @see CRL

 * @see X509CRL

 *

 * @since 1.2

 */

public abstract class CertificateFactorySpi {

    /**

     * 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 abstract Certificate engineGenerateCertificate(InputStream inStream)

        throws CertificateException;

    /**

     * 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.

     *

     * <p> This method was added to version 1.4 of the Java 2 Platform

     * Standard Edition. In order to maintain backwards compatibility with

     * existing service providers, this method cannot be <code>abstract</code>

     * and by default throws an <code>UnsupportedOperationException</code>.

     *

     * @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

     * @exception UnsupportedOperationException if the method is not supported

     * @since 1.4

     */

    public CertPath engineGenerateCertPath(InputStream inStream)

        throws CertificateException

    {

        throw new UnsupportedOperationException();

    }

    /**

     * 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.

     *

     * <p> This method was added to version 1.4 of the Java 2 Platform

     * Standard Edition. In order to maintain backwards compatibility with

     * existing service providers, this method cannot be <code>abstract</code>

     * and by default throws an <code>UnsupportedOperationException</code>.

     *

     * @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

     * @exception UnsupportedOperationException if the method is not supported

     * @since 1.4

     */

    public CertPath engineGenerateCertPath(InputStream inStream,

        String encoding) throws CertificateException

    {

        throw new UnsupportedOperationException();

    }

    /**

     * 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.

     *

     * <p> This method was added to version 1.4 of the Java 2 Platform

     * Standard Edition. In order to maintain backwards compatibility with

     * existing service providers, this method cannot be <code>abstract</code>

     * and by default throws an <code>UnsupportedOperationException</code>.

     *

     * @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

     * @exception UnsupportedOperationException if the method is not supported

     * @since 1.4

     */

    public CertPath

        engineGenerateCertPath(List<? extends Certificate> certificates)

        throws CertificateException

    {

        throw new UnsupportedOperationException();

    }

    /**

     * 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.

     * <p>

     * Attempts to modify the returned <code>Iterator</code> via its

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

     * <code>UnsupportedOperationException</code>.

     *

     * <p> This method was added to version 1.4 of the Java 2 Platform

     * Standard Edition. In order to maintain backwards compatibility with

     * existing service providers, this method cannot be <code>abstract</code>

     * and by default throws an <code>UnsupportedOperationException</code>.

     *

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

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

     * @exception UnsupportedOperationException if the method is not supported

     * @since 1.4

     */

    public Iterator<String> engineGetCertPathEncodings() {

        throw new UnsupportedOperationException();

    }

    /**

     * 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 single DER-encoded certificate

     * in the formats described for

     * {@link CertificateFactory#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 abstract Collection<? extends Certificate>

            engineGenerateCertificates(InputStream inStream)

            throws CertificateException;

    /**

     * 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 abstract CRL engineGenerateCRL(InputStream inStream)

        throws CRLException;

    /**

     * 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 single DER-encoded CRL.

     * 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.

     *

     * @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 abstract Collection<? extends CRL> engineGenerateCRLs

            (InputStream inStream) throws CRLException;

}