java.security.cert

## Class CertificateFactory

- java.lang.Object
- - java.security.cert.CertificateFactory

-     public class CertificateFactory
      extends Object

  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);
       }

  Since:
    1.2
  See Also:
    `Certificate`, `X509Certificate`, `CertPath`, `CRL`, `X509CRL`

- - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `CertificateFactory(CertificateFactorySpi certFacSpi, Provider provider, String type)` Creates a CertificateFactory object of the given type, and encapsulates the given provider implementation (SPI object) in it.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `Certificate` | `generateCertificate(InputStream inStream)` Generates a certificate object and initializes it with the data read from the input stream `inStream`.
    `Collection<? extends Certificate>` | `generateCertificates(InputStream inStream)` Returns a (possibly empty) collection view of the certificates read from the given input stream `inStream`.
    `CertPath` | `generateCertPath(InputStream inStream)` Generates a `CertPath` object and initializes it with the data read from the `InputStream` inStream.
    `CertPath` | `generateCertPath(InputStream inStream, String encoding)` Generates a `CertPath` object and initializes it with the data read from the `InputStream` inStream.
    `CertPath` | `generateCertPath(List<? extends Certificate> certificates)` Generates a `CertPath` object and initializes it with a `List` of `Certificate`s.
    `CRL` | `generateCRL(InputStream inStream)` Generates a certificate revocation list (CRL) object and initializes it with the data read from the input stream `inStream`.
    `Collection<? extends CRL>` | `generateCRLs(InputStream inStream)` Returns a (possibly empty) collection view of the CRLs read from the given input stream `inStream`.
    `Iterator<String>` | `getCertPathEncodings()` Returns an iteration of the `CertPath` encodings supported by this certificate factory, with the default encoding first.
    `static CertificateFactory` | `getInstance(String type)` Returns a certificate factory object that implements the specified certificate type.
    `static CertificateFactory` | `getInstance(String type, Provider provider)` Returns a certificate factory object for the specified certificate type.
    `static CertificateFactory` | `getInstance(String type, String provider)` Returns a certificate factory object for the specified certificate type.
    `Provider` | `getProvider()` Returns the provider of this certificate factory.
    `String` | `getType()` Returns the name of the certificate type associated with this certificate factory.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### CertificateFactory

          protected CertificateFactory(CertificateFactorySpi certFacSpi,
                            Provider provider,
                            String type)

      Creates a CertificateFactory object of the given type, and encapsulates the given provider implementation (SPI object) in it.
      Parameters:
        `certFacSpi` - the provider implementation.
        `provider` - the provider.
        `type` - the certificate type.

  - ### Method Detail

    - #### getInstance

          public static final CertificateFactory getInstance(String type)
                                                      throws CertificateException

      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.

      Parameters:
        `type` - the name of the requested certificate type. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard certificate types.
      Returns:
        a certificate factory object for the specified type.
      Throws:
        `CertificateException` - if no Provider supports a CertificateFactorySpi implementation for the specified type.
      See Also:
        `Provider`

    - #### getInstance

          public static final CertificateFactory getInstance(String type,
                                       String provider)
                                                      throws CertificateException,
                                                             NoSuchProviderException

      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.

      Parameters:
        `type` - the certificate type. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard certificate types.
        `provider` - the name of the provider.
      Returns:
        a certificate factory object for the specified type.
      Throws:
        `CertificateException` - if a CertificateFactorySpi implementation for the specified algorithm is not available from the specified provider.
        `NoSuchProviderException` - if the specified provider is not registered in the security provider list.
        `IllegalArgumentException` - if the provider name is null or empty.
      See Also:
        `Provider`

    - #### getInstance

          public static final CertificateFactory getInstance(String type,
                                       Provider provider)
                                                      throws CertificateException

      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.

      Parameters:
        `type` - the certificate type. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard certificate types.
        `provider` - the provider.
      Returns:
        a certificate factory object for the specified type.
      Throws:
        `CertificateException` - if a CertificateFactorySpi implementation for the specified algorithm is not available from the specified Provider object.
        `IllegalArgumentException` - if the `provider` is null.
      Since:
        1.4
      See Also:
        `Provider`

    - #### getProvider

          public final Provider getProvider()

      Returns the provider of this certificate factory.
      Returns:
        the provider of this certificate factory.

    - #### getType

          public final String getType()

      Returns the name of the certificate type associated with this certificate factory.
      Returns:
        the name of the certificate type associated with this certificate factory.

    - #### generateCertificate

          public final Certificate generateCertificate(InputStream inStream)
                                                throws CertificateException

      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.

      Parameters:
        `inStream` - an input stream with the certificate data.
      Returns:
        a certificate object initialized with the data from the input stream.
      Throws:
        `CertificateException` - on parsing errors.

    - #### getCertPathEncodings

          public final Iterator<String> getCertPathEncodings()

      Returns an iteration of the `CertPath` encodings supported by this certificate factory, with the default encoding first. See Appendix A in the Java Certification Path API Programmer's Guide 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 `String`s)
      Since:
        1.4

    - #### generateCertPath

          public final CertPath generateCertPath(InputStream inStream)
                                          throws CertificateException

      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.
      Parameters:
        `inStream` - an `InputStream` containing the data
      Returns:
        a `CertPath` initialized with the data from the `InputStream`
      Throws:
        `CertificateException` - if an exception occurs while decoding
      Since:
        1.4

    - #### generateCertPath

          public final CertPath generateCertPath(InputStream inStream,
                                  String encoding)
                                          throws CertificateException

      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 Appendix A in the Java Certification Path API Programmer's Guide for information about standard encoding names and their formats.
      Parameters:
        `inStream` - an `InputStream` containing the data
        `encoding` - the encoding used for the data
      Returns:
        a `CertPath` initialized with the data from the `InputStream`
      Throws:
        `CertificateException` - if an exception occurs while decoding or the encoding requested is not supported
      Since:
        1.4

    - #### generateCertPath

          public final CertPath generateCertPath(List<? extends Certificate> certificates)
                                          throws CertificateException

      Generates a `CertPath` object and initializes it with a `List` of `Certificate`s.

      The certificates supplied must be of a type supported by the `CertificateFactory`. They will be copied out of the supplied `List` object.

      Parameters:
        `certificates` - a `List` of `Certificate`s
      Returns:
        a `CertPath` initialized with the supplied list of certificates
      Throws:
        `CertificateException` - if an exception occurs
      Since:
        1.4

    - #### generateCertificates

          public final Collection<? extends Certificate> generateCertificates(InputStream inStream)
                                                                       throws CertificateException

      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.

      Parameters:
        `inStream` - the input stream with the certificates.
      Returns:
        a (possibly empty) collection view of java.security.cert.Certificate objects initialized with the data from the input stream.
      Throws:
        `CertificateException` - on parsing errors.

    - #### generateCRL

          public final CRL generateCRL(InputStream inStream)
                                throws CRLException

      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 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.

      Parameters:
        `inStream` - an input stream with the CRL data.
      Returns:
        a CRL object initialized with the data from the input stream.
      Throws:
        `CRLException` - on parsing errors.

    - #### generateCRLs

          public final Collection<? extends CRL> generateCRLs(InputStream inStream)
                                                       throws CRLException

      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.

      Parameters:
        `inStream` - the input stream with the CRLs.
      Returns:
        a (possibly empty) collection view of java.security.cert.CRL objects initialized with the data from the input stream.
      Throws:
        `CRLException` - on parsing errors.

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