java.security

Class AlgorithmParameters


public class AlgorithmParameters
extends Object

This class is used as an opaque representation of cryptographic parameters.

An AlgorithmParameters object for managing the parameters for a particular algorithm can be obtained by calling one of the getInstance() factory methods (static methods that return instances of a given class).

There are two ways to request such an implementation: by specifying either just an algorithm name, or both an algorithm name and a package provider.

Once an AlgorithmParameters object is returned, it must be initialized via a call to init(), using an appropriate parameter specification or parameter encoding.

A transparent parameter specification is obtained from an AlgorithmParameters object via a call to getParameterSpec(), and a byte encoding of the parameters is obtained via a call to getEncoded().

Since:
1.2
See Also:
AlgorithmParameterSpec, DSAParameterSpec, KeyPairGenerator

Constructor Summary

AlgorithmParameters(AlgorithmParametersSpi paramSpi, Provider provider, String algorithm)
Creates an AlgorithmParameters object.

Method Summary

String
getAlgorithm()
Returns the name of the algorithm associated with this parameter object.
byte[]
getEncoded()
Returns the parameters in their primary encoding format.
byte[]
getEncoded(String format)
Returns the parameters encoded in the specified scheme.
static AlgorithmParameters
getInstance(String algorithm)
Generates a parameter object for the specified algorithm.

If the default provider package provides an implementation of the requested algorithm, an instance of AlgorithmParameters containing that implementation is returned.

static AlgorithmParameters
getInstance(String algorithm, String provider)
Generates a parameter object for the specified algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.

The returned parameter object must be initialized via a call to init(), using an appropriate parameter specification or parameter encoding.

static AlgorithmParameters
getInstance(String algorithm, Provider provider)
Generates an AlgorithmParameterGenerator object for the requested algorithm, as supplied from the specified provider, if such a parameter generator is available from the provider.
AlgorithmParameterSpec
getParameterSpec(Class paramSpec)
Returns a (transparent) specification of this parameter object.
Provider
getProvider()
Returns the provider of this parameter object.
void
init(byte[] params)
Imports the specified parameters and decodes them according to the primary decoding format for parameters.
void
init(byte[] params, String format)
Imports the parameters from params and decodes them according to the specified decoding scheme.
void
init(AlgorithmParameterSpec paramSpec)
Initializes this parameter object using the parameters specified in paramSpec.
String
toString()
Returns a formatted string describing the parameters.

Methods inherited from class java.lang.Object

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

Constructor Details

AlgorithmParameters

protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
                              Provider provider,
                              String algorithm)
Creates an AlgorithmParameters object.
Parameters:
paramSpi - the delegate.
provider - the provider.
algorithm - the algorithm.

Method Details

getAlgorithm

public final String getAlgorithm()
Returns the name of the algorithm associated with this parameter object.
Returns:
the algorithm name.

getEncoded

public final byte[] getEncoded()
            throws IOException
Returns the parameters in their primary encoding format. The primary encoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.
Returns:
the parameters encoded using their primary encoding format.
Throws:
IOException - on encoding errors, or if this parameter object has not been initialized.

getEncoded

public final byte[] getEncoded(String format)
            throws IOException
Returns the parameters encoded in the specified scheme. If format is null, the primary encoding format for parameters is used. The primary encoding format is ASN.1, if an ASN.1 specification for these parameters exists.
Parameters:
format - the name of the encoding format.
Returns:
the parameters encoded using the specified encoding scheme.
Throws:
IOException - on encoding errors, or if this parameter object has not been initialized.

getInstance

public static AlgorithmParameters getInstance(String algorithm)
            throws NoSuchAlgorithmException
Generates a parameter object for the specified algorithm.

If the default provider package provides an implementation of the requested algorithm, an instance of AlgorithmParameters containing that implementation is returned. If the algorithm is not available in the default package, other packages are searched.

The returned parameter object must be initialized via a call to init(), using an appropriate parameter specification or parameter encoding.

Parameters:
algorithm - the name of the algorithm requested.
Returns:
the new parameter object.
Throws:
NoSuchAlgorithmException - if the algorithm is not available in the environment.

getInstance

public static AlgorithmParameters getInstance(String algorithm,
                                              String provider)
            throws NoSuchAlgorithmException,
                   NoSuchProviderException
Generates a parameter object for the specified algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.

The returned parameter object must be initialized via a call to init(), using an appropriate parameter specification or parameter encoding.

Parameters:
algorithm - the name of the algorithm requested.
provider - the name of the provider.
Returns:
the new parameter object.
Throws:
NoSuchAlgorithmException - if the algorithm is not available in the package supplied by the requested provider.
NoSuchProviderException - if the provider is not available in the environment.
IllegalArgumentException - if the provider name is null or empty.
See Also:
Provider

getInstance

public static AlgorithmParameters getInstance(String algorithm,
                                              Provider provider)
            throws NoSuchAlgorithmException
Generates an AlgorithmParameterGenerator object for the requested algorithm, as supplied from the specified provider, if such a parameter generator is available from the provider. Note: the provider doesn't have to be registered.
Parameters:
algorithm - the string name of the algorithm.
provider - the provider.
Returns:
the new AlgorithmParameterGenerator object.
Throws:
NoSuchAlgorithmException - if the algorithm is not available from the provider.
IllegalArgumentException - if the provider is null.
Since:
1.4

getParameterSpec

public final AlgorithmParameterSpec getParameterSpec(Class paramSpec)
            throws InvalidParameterSpecException
Returns a (transparent) specification of this parameter object. paramSpec identifies the specification class in which the parameters should be returned. It could, for example, be DSAParameterSpec.class, to indicate that the parameters should be returned in an instance of the DSAParameterSpec class.
Parameters:
paramSpec - the specification class in which the parameters should be returned.
Returns:
the parameter specification.
Throws:
InvalidParameterSpecException - if the requested parameter specification is inappropriate for this parameter object, or if this parameter object has not been initialized.

getProvider

public final Provider getProvider()
Returns the provider of this parameter object.
Returns:
the provider of this parameter object.

init

public final void init(byte[] params)
            throws IOException
Imports the specified parameters and decodes them according to the primary decoding format for parameters. The primary decoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.
Parameters:
params - the encoded parameters.
Throws:
IOException - on decoding errors, or if this parameter object has already been initialized.

init

public final void init(byte[] params,
                       String format)
            throws IOException
Imports the parameters from params and decodes them according to the specified decoding scheme. If format is null, the primary decoding format for parameters is used. The primary decoding format is ASN.1, if an ASN.1 specification for these parameters exists.
Parameters:
params - the encoded parameters.
format - the name of the decoding scheme.
Throws:
IOException - on decoding errors, or if this parameter object has already been initialized.

init

public final void init(AlgorithmParameterSpec paramSpec)
            throws InvalidParameterSpecException
Initializes this parameter object using the parameters specified in paramSpec.
Parameters:
paramSpec - the parameter specification.
Throws:
InvalidParameterSpecException - if the given parameter specification is inappropriate for the initialization of this parameter object, or if this parameter object has already been initialized.

toString

public final String toString()
Returns a formatted string describing the parameters.
Overrides:
toString in interface Object
Returns:
a formatted string describing the parameters, or null if this parameter object has not been initialized.

AlgorithmParameters.java --- Algorithm Parameters Implementation Class Copyright (C) 1999, 2003, 2004 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.