# 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);
    }

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.

Since:
  1.2
External Specifications
  - Java Security Standard Algorithm Names
See Also:
  - `Certificate`
  - `X509Certificate`
  - `CertPath`
  - `CRL`
  - `X509CRL`

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  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

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

  ### Methods declared in class Object

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

- ## Constructor Details

  - ### 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 Details

  - ### 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.

    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 from the order of providers returned by `Security.getProviders()`.
    Parameters:
      `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.
    Returns:
      a certificate factory object for the specified type
    Throws:
      `CertificateException` - if no `Provider` supports a `CertificateFactorySpi` implementation for the specified type
      `NullPointerException` - if `type` is `null`
    External Specifications
      - Java Security Standard Algorithm Names
    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 the CertificateFactory section in the Java Security Standard Algorithm Names Specification 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
      `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`
    External Specifications
      - Java Security Standard Algorithm Names
    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 the CertificateFactory section in the Java Security Standard Algorithm Names Specification 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`
      `NullPointerException` - if `type` is `null`
    Since:
      1.4
    External Specifications
      - Java Security Standard Algorithm Names
    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 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 `String`s)
    Since:
      1.4
    External Specifications
      - Java Security Standard Algorithm Names

  - ### 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 the CertPath Encodings section in the Java Security Standard Algorithm Names Specification 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
    External Specifications
      - Java Security Standard Algorithm Names

  - ### 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 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.