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).

Once an AlgorithmParameters object is obtained, it must be initialized via a call to init, using an appropriate parameter specification or parameter encoding. 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           Returns           Generates a parameter object for the specified algorithm.
static  AlgorithmParameters	getInstance ( String  algorithm, Provider           Returns           Generates a parameter object for the specified algorithm. algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.
static  AlgorithmParameters	getInstance ( String  algorithm, String           Returns           Generates a parameter object for the specified algorithm. algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.
<T extends AlgorithmParameterSpec > T	getParameterSpec ( Class <T> 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

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

Returns Generates a parameter object for the specified algorithm.

This method traverses the list of registered security Providers, starting with the most preferred Provider. A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi implementation from the first Provider that supports the specified algorithm is returned. 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.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

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. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.

Returns:

the new parameter object.

Throws:

NoSuchAlgorithmException - if no Provider supports an AlgorithmParametersSpi implementation for the specified algorithm.

See Also:

Provider - if the algorithm is not available in the environment.

getInstance

public static AlgorithmParameters getInstance(String algorithm,
                                              String provider)
                                       throws NoSuchAlgorithmException,
                                              NoSuchProviderException

Returns a parameter object for the specified algorithm. Generates a parameter object for the specified algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.

A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi 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.

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. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.

provider - the name of the provider.

Returns:

the new parameter object.

Throws:

NoSuchAlgorithmException - if an AlgorithmParametersSpi implementation for the specified algorithm is not available from in the specified package supplied by the requested provider.

NoSuchProviderException - if the specified provider is not registered available in the security provider list. environment.

IllegalArgumentException - if the provider name is null or empty.

See Also:

Provider

getInstance

public static AlgorithmParameters getInstance(String algorithm,
                                              Provider provider)
                                       throws NoSuchAlgorithmException

Returns a parameter object for the specified algorithm. 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.

A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.

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. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.

provider - the name of the provider.

Returns:

the new parameter object.

Throws:

NoSuchAlgorithmException - if an AlgorithmParameterGeneratorSpi implementation for the specified algorithm is not available from in the specified Provider object. 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 <T extends AlgorithmParameterSpec> T getParameterSpec(Class<T> 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.