java.security
Class AlgorithmParameters

java.lang.Object
  java.security.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.

• If just an algorithm name is specified, the system will determine if there is an AlgorithmParameters implementation for the algorithm requested available in the environment, and if there is more than one, if there is a preferred one.
• If both an algorithm name and a package provider are specified, the system will determine if there is an implementation in the package requested, and throw an exception if there is not.

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

protected

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.
static AlgorithmParameters	getInstance(String algorithm, Provider provider) Generates a parameter object for the specified algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.
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.
AlgorithmParameterSpec	getParameterSpec(Class paramSpec) Returns a (transparent) specification of this parameter object.
Provider	getProvider() Returns the provider of this parameter object.
void	init(AlgorithmParameterSpec paramSpec) Initializes this parameter object using the parameters specified in paramSpec.
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.
String	toString() Returns a formatted string describing the parameters.

Methods inherited from class java.lang.Object

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

Constructor Detail

AlgorithmParameters

protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
                              Provider provider,
                              String algorithm)

Creates an AlgorithmParameters object.

Parameters:

paramSpi - the delegate

provider - the provider

algorithm - the algorithm

Method Detail

getAlgorithm

public final String getAlgorithm()

Returns the name of the algorithm associated with this parameter object.

Returns:

the algorithm name.

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 a parameter object for the specified algorithm, as supplied by the specified provider, if such an algorithm is available from the provider. Note: the provider doesn't have to be registered.

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.

IllegalArgumentException - if the provider is null.

Since:

1.4

See Also:

Provider

getProvider

public final Provider getProvider()

Returns the provider of this parameter object.

Returns:

the provider of this parameter object

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.

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.

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.

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.

toString

public final String toString()

Returns a formatted string describing the parameters.

Overrides:

toString in class Object

Returns:

a formatted string describing the parameters, or null if this parameter object has not been initialized.