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);
 }
 

Android provides the following CertificateFactory types:

Algorithm	Supported API Levels
X.509	1+

and the following CertPath encodings:

Name	Supported (API Levels)
PKCS7	1+
PkiPath	1+

The type and encodings are described in the CertificateFactory section and the CertPath Encodings section of the Java Cryptography Architecture Standard Algorithm Name Documentation.

See Also

• Certificate
• X509Certificate
• CertPath
• CRL
• X509CRL

Protected Constructor Summary

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.

Public Method Summary

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 CertPath	generateCertPath(List<? extends Certificate> certificates) Generates a CertPath object and initializes it with a List of Certificates.
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 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 Iterator<String>	getCertPathEncodings() Returns an iteration of the CertPath encodings supported by this certificate factory, with the default encoding first.
final static CertificateFactory	getInstance(String type) Returns a certificate factory object that implements the specified certificate type.
final static CertificateFactory	getInstance(String type, String provider) Returns a certificate factory object for the specified certificate type.
final static 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.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Protected Constructors

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.

Public Methods

public final CRL generateCRL (InputStream 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.

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.

public final Collection<? extends CRL> generateCRLs (InputStream 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.

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.

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

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.

Parameters

certificates	a List of Certificates

Returns

• a CertPath initialized with the supplied list of certificates

Throws

CertificateException	if an exception occurs

public final CertPath generateCertPath (InputStream inStream)

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

public final CertPath generateCertPath (InputStream inStream, String encoding)

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 Cryptography Architecture Standard Algorithm Name Documentation 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

public final Certificate generateCertificate (InputStream inStream)

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.

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

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.

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 Cryptography Architecture Standard Algorithm Name Documentation 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)

public static final CertificateFactory getInstance (String 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.

Parameters

type	the name of the requested certificate type. See the CertificateFactory section in the Java Cryptography Architecture Standard Algorithm Name Documentation 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

public static final CertificateFactory getInstance (String type, String provider)

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 Cryptography Architecture Standard Algorithm Name Documentation 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

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

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 Cryptography Architecture Standard Algorithm Name Documentation 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.

See Also

• Provider

public final Provider getProvider ()

Returns the provider of this certificate factory.

Returns

• the provider of this certificate factory.

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.